Android高级UI开发 RecyclerView高级进阶（八）下拉刷新，上拉加载
【摘要】 Listview的下拉刷新，上拉加载我们常用的框架是pullToRefresh。今天我们来介绍RecyclerView如何实现下拉刷新，上拉加载。
源码下载： 源码
1. 下拉刷新
实现思路，无需我们写代码自定义下拉刷新控件，直接使用MaterialDesign5.0为我们提供的SwipeRefreshLayout控件。
布局一般为：
<android.supp...
Listview的下拉刷新，上拉加载我们常用的框架是pullToRefresh。今天我们来介绍RecyclerView如何实现下拉刷新，上拉加载。
源码下载： 源码
1. 下拉刷新
实现思路，无需我们写代码自定义下拉刷新控件，直接使用MaterialDesign5.0为我们提供的SwipeRefreshLayout控件。
布局一般为：
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<android.support.v4.widget.SwipeRefreshLayout
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android:id="@+id/refresh_layout"
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android:layout_width="match_parent"
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android:layout_height="wrap_content"
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app:layout_behavior="@string/appbar_scrolling_view_behavior">
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<com.yanzhenjie.recyclerview.swipe.SwipeMenuRecyclerView
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android:id="@+id/recycler_view"
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android:layout_width="match_parent"
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android:layout_height="wrap_content"/>
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</android.support.v4.widget.SwipeRefreshLayout>
2. 上拉加载
实现思路, 需要我们自己写代码来实现。在这里我们先贴出MainActivity的代码（使用RecyclerView控件的核心代码）
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/*
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* Copyright 2017 Yan Zhenjie
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.anyikang.volunteer.sos.recyclerview22.activity.load;
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import android.os.Bundle;
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import android.support.annotation.Nullable;
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import android.support.v4.content.ContextCompat;
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import android.support.v4.widget.SwipeRefreshLayout;
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import android.support.v7.app.ActionBar;
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import android.support.v7.app.AppCompatActivity;
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import android.support.v7.widget.LinearLayoutManager;
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import android.support.v7.widget.Toolbar;
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import android.view.MenuItem;
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import android.view.View;
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import android.widget.Toast;
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import com.anyikang.volunteer.sos.recyclerview22.R;
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import com.anyikang.volunteer.sos.recyclerview22.adapter.MainAdapter;
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import com.yanzhenjie.recyclerview.swipe.SwipeItemClickListener;
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import com.yanzhenjie.recyclerview.swipe.SwipeMenuRecyclerView;
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import com.yanzhenjie.recyclerview.swipe.widget.DefaultItemDecoration;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* <p>
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* 默认的加载更多的View。
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* </p>
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*
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*/
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public class DefaultActivity extends AppCompatActivity {
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private SwipeRefreshLayout mRefreshLayout;
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private SwipeMenuRecyclerView mRecyclerView;
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private MainAdapter mAdapter;
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private List<String> mDataList;
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@Override
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protected void onCreate(@Nullable Bundle savedInstanceState) {
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super.onCreate(savedInstanceState);
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setContentView(R.layout.activity_refresh_loadmore);
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Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
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setSupportActionBar(toolbar);
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ActionBar actionBar = getSupportActionBar();
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assert actionBar != null;
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actionBar.setDisplayHomeAsUpEnabled(true);
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mRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.refresh_layout);
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mRefreshLayout.setOnRefreshListener(mRefreshListener); // 刷新监听。
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mRecyclerView = (SwipeMenuRecyclerView) findViewById(R.id.recycler_view);
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// mRecyclerView.setLayoutManager(new GridLayoutManager(this, 2));
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mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
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mRecyclerView.addItemDecoration(new DefaultItemDecoration(ContextCompat.getColor(this, R.color.divider_color)));
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mRecyclerView.setSwipeItemClickListener(mItemClickListener); // RecyclerView Item点击监听。
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mRecyclerView.useDefaultLoadMore(); // 使用默认的加载更多的View。
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mRecyclerView.setLoadMoreListener(mLoadMoreListener); // 加载更多的监听。
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mAdapter = new MainAdapter(this);
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mRecyclerView.setAdapter(mAdapter);
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// 请求服务器加载数据。
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loadData();
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}
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/**
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* 刷新。
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*/
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private SwipeRefreshLayout.OnRefreshListener mRefreshListener = new SwipeRefreshLayout.OnRefreshListener() {
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@Override
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public void onRefresh() {
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mRecyclerView.postDelayed(new Runnable() {
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@Override
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public void run() {
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loadData();
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}
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}, 1000); // 延时模拟请求服务器。
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}
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};
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/**
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* 加载更多。
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*/
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private SwipeMenuRecyclerView.LoadMoreListener mLoadMoreListener = new SwipeMenuRecyclerView.LoadMoreListener() {
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@Override
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public void onLoadMore() {
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mRecyclerView.postDelayed(new Runnable() {
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@Override
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public void run() {
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List<String> strings = createDataList(mAdapter.getItemCount());
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mDataList.addAll(strings);
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// notifyItemRangeInserted()或者notifyDataSetChanged().
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mAdapter.notifyItemRangeInserted(mDataList.size() - strings.size(), strings.size());
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// 数据完更多数据，一定要掉用这个方法。
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// 第一个参数：表示此次数据是否为空。
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// 第二个参数：表示是否还有更多数据。
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mRecyclerView.loadMoreFinish(false, true);
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// 如果加载失败调用下面的方法，传入errorCode和errorMessage。
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// errorCode随便传，你自定义LoadMoreView时可以根据errorCode判断错误类型。
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// errorMessage是会显示到loadMoreView上的，用户可以看到。
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// mRecyclerView.loadMoreError(0, "请求网络失败");
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}
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}, 1000);
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}
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};
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/**
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* Item点击监听。
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*/
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private SwipeItemClickListener mItemClickListener = new SwipeItemClickListener() {
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@Override
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public void onItemClick(View itemView, int position) {
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Toast.makeText(DefaultActivity.this, "第" + position + "个", Toast.LENGTH_SHORT).show();
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}
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};
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/**
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* 第一次加载数据。
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*/
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private void loadData() {
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mDataList = createDataList(0);
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mAdapter.notifyDataSetChanged(mDataList);
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mRefreshLayout.setRefreshing(false);
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// 第一次加载数据：一定要调用这个方法，否则不会触发加载更多。
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// 第一个参数：表示此次数据是否为空，假如你请求到的list为空(== null || list.size == 0)，那么这里就要true。
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// 第二个参数：表示是否还有更多数据，根据服务器返回给你的page等信息判断是否还有更多，这样可以提供性能，如果不能判断则传true。
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mRecyclerView.loadMoreFinish(false, true);
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}
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protected List<String> createDataList(int start) {
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List<String> strings = new ArrayList<>();
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for (int i = start; i < start + 100; i++) {
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strings.add("第" + i + "个Item");
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}
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return strings;
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}
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@Override
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public boolean onOptionsItemSelected(MenuItem item) {
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if (item.getItemId() == android.R.id.home) {
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finish();
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}
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return true;
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}
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}
2.1分析代码
SwipeMenuRecyclerView mRecyclerView
从这个声明可以看出我们需要扩展一个自定义RecyclerView控件。
mRecyclerView.setLoadMoreListener(mLoadMoreListener); // 加载更多的监听
这行代码说明“上拉加载更多”这个事件的触发一定是在自定义RecyclerView里，即SwipeMenuRecyclerView。
而“上拉加载更多”这个事件触发后的 处理或者说响应代码是在mLoadMoreListener这个接口的实例对象里。
综上分析，主要看以下2个部分
（1）SwipeMenuRecyclerView这个自定义RecyclerView的代码，看其“上拉加载”事件是如何触发的。
（2）mLoadMoreListener接口的实现代码，已经在MainActivity里展示过了，mLoadMoreListener实现了onLoadMore函数。也就说在SwipeMenuRecyclerView里“上拉加载”事件触发时一定会回调MainActivity中的mLoadMoreListener的onLoadMore函数。
在这里我们贴出SwipeMenuRecyclerView的代码，分析一下“上拉加载”事件是如何触发的。
SwipeMenuRecyclerView.java:
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/*
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* Copyright 2016 Yan Zhenjie
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.yanzhenjie.recyclerview.swipe;
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import android.content.Context;
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import android.support.annotation.IntDef;
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import android.support.v7.widget.GridLayoutManager;
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import android.support.v7.widget.LinearLayoutManager;
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import android.support.v7.widget.RecyclerView;
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import android.support.v7.widget.StaggeredGridLayoutManager;
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import android.util.AttributeSet;
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import android.view.MotionEvent;
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import android.view.View;
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import android.view.ViewConfiguration;
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import android.view.ViewGroup;
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import android.view.ViewParent;
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import com.yanzhenjie.recyclerview.swipe.touch.DefaultItemTouchHelper;
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import com.yanzhenjie.recyclerview.swipe.touch.OnItemMoveListener;
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import com.yanzhenjie.recyclerview.swipe.touch.OnItemMovementListener;
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import com.yanzhenjie.recyclerview.swipe.touch.OnItemStateChangedListener;
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import com.yanzhenjie.recyclerview.swipe.widget.DefaultLoadMoreView;
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import java.lang.annotation.Retention;
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import java.lang.annotation.RetentionPolicy;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* Created by
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*/
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public class SwipeMenuRecyclerView extends RecyclerView {
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/**
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* Left menu.
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*/
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public static final int LEFT_DIRECTION = 1;
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/**
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* Right menu.
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*/
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public static final int RIGHT_DIRECTION = -1;
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@IntDef({LEFT_DIRECTION, RIGHT_DIRECTION})
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@Retention(RetentionPolicy.SOURCE)
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public @interface DirectionMode {
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}
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/**
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* Invalid position.
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*/
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private static final int INVALID_POSITION = -1;
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protected int mScaleTouchSlop;
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protected SwipeMenuLayout mOldSwipedLayout;
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protected int mOldTouchedPosition = INVALID_POSITION;
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private int mDownX;
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private int mDownY;
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private boolean allowSwipeDelete = false;
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private DefaultItemTouchHelper mDefaultItemTouchHelper;
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private SwipeMenuCreator mSwipeMenuCreator;
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private SwipeMenuItemClickListener mSwipeMenuItemClickListener;
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private SwipeItemClickListener mSwipeItemClickListener;
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private SwipeItemLongClickListener mSwipeItemLongClickListener;
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private SwipeAdapterWrapper mAdapterWrapper;
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public SwipeMenuRecyclerView(Context context) {
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this(context, null);
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}
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public SwipeMenuRecyclerView(Context context, AttributeSet attrs) {
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this(context, attrs, 0);
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}
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public SwipeMenuRecyclerView(Context context, AttributeSet attrs, int defStyle) {
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super(context, attrs, defStyle);
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mScaleTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
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}
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private void initializeItemTouchHelper() {
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if (mDefaultItemTouchHelper == null) {
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mDefaultItemTouchHelper = new DefaultItemTouchHelper();
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mDefaultItemTouchHelper.attachToRecyclerView(this);
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}
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}
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/**
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* Set OnItemMoveListener.
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*
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* @param onItemMoveListener {@link OnItemMoveListener}.
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*/
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public void setOnItemMoveListener(OnItemMoveListener onItemMoveListener) {
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initializeItemTouchHelper();
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this.mDefaultItemTouchHelper.setOnItemMoveListener(onItemMoveListener);
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}
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/**
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* Set OnItemMovementListener.
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*
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* @param onItemMovementListener {@link OnItemMovementListener}.
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*/
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public void setOnItemMovementListener(OnItemMovementListener onItemMovementListener) {
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initializeItemTouchHelper();
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this.mDefaultItemTouchHelper.setOnItemMovementListener(onItemMovementListener);
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}
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/**
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* Set OnItemStateChangedListener.
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*
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* @param onItemStateChangedListener {@link OnItemStateChangedListener}.
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*/
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public void setOnItemStateChangedListener(OnItemStateChangedListener onItemStateChangedListener) {
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initializeItemTouchHelper();
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this.mDefaultItemTouchHelper.setOnItemStateChangedListener(onItemStateChangedListener);
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}
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/**
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* Set can long press drag.
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*
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* @param canDrag drag true, otherwise is can't.
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*/
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public void setLongPressDragEnabled(boolean canDrag) {
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initializeItemTouchHelper();
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this.mDefaultItemTouchHelper.setLongPressDragEnabled(canDrag);
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}
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/**
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* Get can long press drag.
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*
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* @return drag true, otherwise is can't.
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*/
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public boolean isLongPressDragEnabled() {
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initializeItemTouchHelper();
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return this.mDefaultItemTouchHelper.isLongPressDragEnabled();
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}
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/**
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* Set can swipe delete.
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*
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* @param canSwipe swipe true, otherwise is can't.
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*/
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public void setItemViewSwipeEnabled(boolean canSwipe) {
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initializeItemTouchHelper();
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allowSwipeDelete = canSwipe; // swipe and menu conflict.
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this.mDefaultItemTouchHelper.setItemViewSwipeEnabled(canSwipe);
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}
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/**
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* Get can long press swipe.
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*
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* @return swipe true, otherwise is can't.
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*/
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public boolean isItemViewSwipeEnabled() {
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initializeItemTouchHelper();
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return this.mDefaultItemTouchHelper.isItemViewSwipeEnabled();
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}
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/**
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* Start drag a item.
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*
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* @param viewHolder the ViewHolder to start dragging. It must be a direct child of RecyclerView.
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*/
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public void startDrag(RecyclerView.ViewHolder viewHolder) {
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initializeItemTouchHelper();
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this.mDefaultItemTouchHelper.startDrag(viewHolder);
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}
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/**
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* Star swipe a item.
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*
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* @param viewHolder the ViewHolder to start swiping. It must be a direct child of RecyclerView.
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*/
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public void startSwipe(RecyclerView.ViewHolder viewHolder) {
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initializeItemTouchHelper();
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this.mDefaultItemTouchHelper.startSwipe(viewHolder);
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}
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/**
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* Check the Adapter and throw an exception if it already exists.
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*/
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private void checkAdapterExist(String message) {
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if (mAdapterWrapper != null)
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throw new IllegalStateException(message);
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}
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/**
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* Set item click listener.
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*/
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public void setSwipeItemClickListener(SwipeItemClickListener itemClickListener) {
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if (itemClickListener == null) return;
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checkAdapterExist("Cannot set item click listener, setAdapter has already been called.");
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this.mSwipeItemClickListener = new ItemClick(this, itemClickListener);
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}
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private static class ItemClick implements SwipeItemClickListener {
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private SwipeMenuRecyclerView mRecyclerView;
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private SwipeItemClickListener mCallback;
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public ItemClick(SwipeMenuRecyclerView recyclerView, SwipeItemClickListener callback) {
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this.mRecyclerView = recyclerView;
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this.mCallback = callback;
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}
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@Override
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public void onItemClick(View itemView, int position) {
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position = position - mRecyclerView.getHeaderItemCount();
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if (position >= 0)
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mCallback.onItemClick(itemView, position);
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}
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}
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/**
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* Set item click listener.
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*/
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public void setSwipeItemLongClickListener(SwipeItemLongClickListener itemLongClickListener) {
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if (itemLongClickListener == null) return;
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checkAdapterExist("Cannot set item long click listener, setAdapter has already been called.");
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this.mSwipeItemLongClickListener = new ItemLongClick(this, itemLongClickListener);
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}
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private static class ItemLongClick implements SwipeItemLongClickListener {
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private SwipeMenuRecyclerView mRecyclerView;
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private SwipeItemLongClickListener mCallback;
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public ItemLongClick(SwipeMenuRecyclerView recyclerView, SwipeItemLongClickListener callback) {
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this.mRecyclerView = recyclerView;
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this.mCallback = callback;
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}
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@Override
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public void onItemLongClick(View itemView, int position) {
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position = position - mRecyclerView.getHeaderItemCount();
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if (position >= 0)
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mCallback.onItemLongClick(itemView, position);
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}
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}
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/**
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* Set to create menu listener.
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*/
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public void setSwipeMenuCreator(SwipeMenuCreator menuCreator) {
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if (menuCreator == null) return;
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checkAdapterExist("Cannot set menu creator, setAdapter has already been called.");
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this.mSwipeMenuCreator = menuCreator;
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}
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/**
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* Set to click menu listener.
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*/
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public void setSwipeMenuItemClickListener(SwipeMenuItemClickListener menuItemClickListener) {
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if (menuItemClickListener == null) return;
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checkAdapterExist("Cannot set menu item click listener, setAdapter has already been called.");
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this.mSwipeMenuItemClickListener = new MenuItemClick(this, menuItemClickListener);
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}
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private static class MenuItemClick implements SwipeMenuItemClickListener {
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private SwipeMenuRecyclerView mRecyclerView;
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private SwipeMenuItemClickListener mCallback;
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public MenuItemClick(SwipeMenuRecyclerView recyclerView, SwipeMenuItemClickListener callback) {
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this.mRecyclerView = recyclerView;
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this.mCallback = callback;
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}
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@Override
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public void onItemClick(SwipeMenuBridge menuBridge) {
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int position = menuBridge.getAdapterPosition();
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position = position - mRecyclerView.getHeaderItemCount();
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if (position >= 0) {
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menuBridge.mAdapterPosition = position;
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mCallback.onItemClick(menuBridge);
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}
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}
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}
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@Override
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public void setLayoutManager(LayoutManager layoutManager) {
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if (layoutManager instanceof GridLayoutManager) {
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final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
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final GridLayoutManager.SpanSizeLookup spanSizeLookupHolder = gridLayoutManager.getSpanSizeLookup();
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gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
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@Override
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public int getSpanSize(int position) {
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if (mAdapterWrapper.isHeaderView(position) || mAdapterWrapper.isFooterView(position)) {
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return gridLayoutManager.getSpanCount();
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}
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if (spanSizeLookupHolder != null)
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return spanSizeLookupHolder.getSpanSize(position - getHeaderItemCount());
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return 1;
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}
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});
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}
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super.setLayoutManager(layoutManager);
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}
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/**
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* Get the original adapter.
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*/
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public Adapter getOriginAdapter() {
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if (mAdapterWrapper == null) return null;
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return mAdapterWrapper.getOriginAdapter();
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}
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@Override
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public void setAdapter(Adapter adapter) {
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if (mAdapterWrapper != null) {
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mAdapterWrapper.getOriginAdapter().unregisterAdapterDataObserver(mAdapterDataObserver);
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}
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if (adapter == null) {
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mAdapterWrapper = null;
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} else {
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adapter.registerAdapterDataObserver(mAdapterDataObserver);
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mAdapterWrapper = new SwipeAdapterWrapper(getContext(), adapter);
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mAdapterWrapper.setSwipeItemClickListener(mSwipeItemClickListener);
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mAdapterWrapper.setSwipeItemLongClickListener(mSwipeItemLongClickListener);
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mAdapterWrapper.setSwipeMenuCreator(mSwipeMenuCreator);
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mAdapterWrapper.setSwipeMenuItemClickListener(mSwipeMenuItemClickListener);
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if (mHeaderViewList.size() > 0) {
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for (View view : mHeaderViewList) {
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mAdapterWrapper.addHeaderView(view);
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}
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}
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if (mFooterViewList.size() > 0) {
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for (View view : mFooterViewList) {
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mAdapterWrapper.addFooterView(view);
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}
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}
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}
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super.setAdapter(mAdapterWrapper);
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}
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private AdapterDataObserver mAdapterDataObserver = new AdapterDataObserver() {
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@Override
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public void onChanged() {
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mAdapterWrapper.notifyDataSetChanged();
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}
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@Override
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public void onItemRangeChanged(int positionStart, int itemCount) {
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positionStart += getHeaderItemCount();
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mAdapterWrapper.notifyItemRangeChanged(positionStart, itemCount);
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}
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@Override
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public void onItemRangeChanged(int positionStart, int itemCount, Object payload) {
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positionStart += getHeaderItemCount();
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mAdapterWrapper.notifyItemRangeChanged(positionStart, itemCount, payload);
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}
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@Override
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public void onItemRangeInserted(int positionStart, int itemCount) {
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positionStart += getHeaderItemCount();
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mAdapterWrapper.notifyItemRangeInserted(positionStart, itemCount);
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}
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@Override
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public void onItemRangeRemoved(int positionStart, int itemCount) {
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positionStart += getHeaderItemCount();
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mAdapterWrapper.notifyItemRangeRemoved(positionStart, itemCount);
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}
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@Override
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public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
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fromPosition += getHeaderItemCount();
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toPosition += getHeaderItemCount();
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mAdapterWrapper.notifyItemMoved(fromPosition, toPosition);
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}
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};
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private List<View> mHeaderViewList = new ArrayList<>();
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private List<View> mFooterViewList = new ArrayList<>();
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/**
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* Add view at the headers.
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*/
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public void addHeaderView(View view) {
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mHeaderViewList.add(view);
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if (mAdapterWrapper != null) {
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mAdapterWrapper.addHeaderViewAndNotify(view);
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}
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}
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/**
-
* Remove view from header.
-
*/
-
public void removeHeaderView(View view) {
-
mHeaderViewList.remove(view);
-
if (mAdapterWrapper != null) {
-
mAdapterWrapper.removeHeaderViewAndNotify(view);
-
}
-
}
-
-
/**
-
* Add view at the footer.
-
*/
-
public void addFooterView(View view) {
-
mFooterViewList.add(view);
-
if (mAdapterWrapper != null) {
-
mAdapterWrapper.addFooterViewAndNotify(view);
-
}
-
}
-
-
public void removeFooterView(View view) {
-
mFooterViewList.remove(view);
-
if (mAdapterWrapper != null) {
-
mAdapterWrapper.removeFooterViewAndNotify(view);
-
}
-
}
-
-
/**
-
* Get size of headers.
-
*/
-
public int getHeaderItemCount() {
-
if (mAdapterWrapper == null) return 0;
-
return mAdapterWrapper.getHeaderItemCount();
-
}
-
-
/**
-
* Get size of footer.
-
*/
-
public int getFooterItemCount() {
-
if (mAdapterWrapper == null) return 0;
-
return mAdapterWrapper.getFooterItemCount();
-
}
-
-
/**
-
* Get ViewType of item.
-
*/
-
public int getItemViewType(int position) {
-
if (mAdapterWrapper == null) return 0;
-
return mAdapterWrapper.getItemViewType(position);
-
}
-
-
/**
-
* open menu on left.
-
*
-
* @param position position.
-
*/
-
public void smoothOpenLeftMenu(int position) {
-
smoothOpenMenu(position, LEFT_DIRECTION, SwipeMenuLayout.DEFAULT_SCROLLER_DURATION);
-
}
-
-
/**
-
* open menu on left.
-
*
-
* @param position position.
-
* @param duration time millis.
-
*/
-
public void smoothOpenLeftMenu(int position, int duration) {
-
smoothOpenMenu(position, LEFT_DIRECTION, duration);
-
}
-
-
/**
-
* open menu on right.
-
*
-
* @param position position.
-
*/
-
public void smoothOpenRightMenu(int position) {
-
smoothOpenMenu(position, RIGHT_DIRECTION, SwipeMenuLayout.DEFAULT_SCROLLER_DURATION);
-
}
-
-
/**
-
* open menu on right.
-
*
-
* @param position position.
-
* @param duration time millis.
-
*/
-
public void smoothOpenRightMenu(int position, int duration) {
-
smoothOpenMenu(position, RIGHT_DIRECTION, duration);
-
}
-
-
/**
-
* open menu.
-
*
-
* @param position position.
-
* @param direction use {@link #LEFT_DIRECTION}, {@link #RIGHT_DIRECTION}.
-
* @param duration time millis.
-
*/
-
public void smoothOpenMenu(int position, @DirectionMode int direction, int duration) {
-
if (mOldSwipedLayout != null) {
-
if (mOldSwipedLayout.isMenuOpen()) {
-
mOldSwipedLayout.smoothCloseMenu();
-
}
-
}
-
position += getHeaderItemCount();
-
ViewHolder vh = findViewHolderForAdapterPosition(position);
-
if (vh != null) {
-
View itemView = getSwipeMenuView(vh.itemView);
-
if (itemView instanceof SwipeMenuLayout) {
-
mOldSwipedLayout = (SwipeMenuLayout) itemView;
-
if (direction == RIGHT_DIRECTION) {
-
mOldTouchedPosition = position;
-
mOldSwipedLayout.smoothOpenRightMenu(duration);
-
} else if (direction == LEFT_DIRECTION) {
-
mOldTouchedPosition = position;
-
mOldSwipedLayout.smoothOpenLeftMenu(duration);
-
}
-
}
-
}
-
}
-
-
/**
-
* Close menu.
-
*/
-
public void smoothCloseMenu() {
-
if (mOldSwipedLayout != null && mOldSwipedLayout.isMenuOpen()) {
-
mOldSwipedLayout.smoothCloseMenu();
-
}
-
}
-
-
@Override
-
public boolean onInterceptTouchEvent(MotionEvent e) {
-
boolean isIntercepted = super.onInterceptTouchEvent(e);
-
if (allowSwipeDelete) // swipe and menu conflict.
-
return isIntercepted;
-
else {
-
if (e.getPointerCount() > 1) return true;
-
int action = e.getAction();
-
int x = (int) e.getX();
-
int y = (int) e.getY();
-
switch (action) {
-
case MotionEvent.ACTION_DOWN: {
-
mDownX = x;
-
mDownY = y;
-
isIntercepted = false;
-
-
int touchingPosition = getChildAdapterPosition(findChildViewUnder(x, y));
-
if (touchingPosition != mOldTouchedPosition && mOldSwipedLayout != null && mOldSwipedLayout.isMenuOpen()) {
-
mOldSwipedLayout.smoothCloseMenu();
-
isIntercepted = true;
-
}
-
-
if (isIntercepted) {
-
mOldSwipedLayout = null;
-
mOldTouchedPosition = INVALID_POSITION;
-
} else {
-
ViewHolder vh = findViewHolderForAdapterPosition(touchingPosition);
-
if (vh != null) {
-
View itemView = getSwipeMenuView(vh.itemView);
-
if (itemView instanceof SwipeMenuLayout) {
-
mOldSwipedLayout = (SwipeMenuLayout) itemView;
-
mOldTouchedPosition = touchingPosition;
-
}
-
}
-
}
-
break;
-
}
-
// They are sensitive to retain sliding and inertia.
-
case MotionEvent.ACTION_MOVE: {
-
isIntercepted = handleUnDown(x, y, isIntercepted);
-
if (mOldSwipedLayout == null) break;
-
ViewParent viewParent = getParent();
-
if (viewParent == null) break;
-
-
int disX = mDownX - x;
-
// 向左滑，显示右侧菜单，或者关闭左侧菜单。
-
boolean showRightCloseLeft = disX > 0 && (mOldSwipedLayout.hasRightMenu() || mOldSwipedLayout.isLeftCompleteOpen());
-
// 向右滑，显示左侧菜单，或者关闭右侧菜单。
-
boolean showLeftCloseRight = disX < 0 && (mOldSwipedLayout.hasLeftMenu() || mOldSwipedLayout.isRightCompleteOpen());
-
viewParent.requestDisallowInterceptTouchEvent(showRightCloseLeft || showLeftCloseRight);
-
}
-
case MotionEvent.ACTION_UP:
-
case MotionEvent.ACTION_CANCEL: {
-
isIntercepted = handleUnDown(x, y, isIntercepted);
-
break;
-
}
-
}
-
}
-
return isIntercepted;
-
}
-
-
private boolean handleUnDown(int x, int y, boolean defaultValue) {
-
int disX = mDownX - x;
-
int disY = mDownY - y;
-
-
// swipe
-
if (Math.abs(disX) > mScaleTouchSlop && Math.abs(disX) > Math.abs(disY))
-
return false;
-
// click
-
if (Math.abs(disY) < mScaleTouchSlop && Math.abs(disX) < mScaleTouchSlop)
-
return false;
-
return defaultValue;
-
}
-
-
@Override
-
public boolean onTouchEvent(MotionEvent e) {
-
int action = e.getAction();
-
switch (action) {
-
case MotionEvent.ACTION_DOWN:
-
break;
-
case MotionEvent.ACTION_MOVE:
-
if (mOldSwipedLayout != null && mOldSwipedLayout.isMenuOpen()) {
-
mOldSwipedLayout.smoothCloseMenu();
-
}
-
break;
-
case MotionEvent.ACTION_UP:
-
break;
-
case MotionEvent.ACTION_CANCEL:
-
break;
-
}
-
return super.onTouchEvent(e);
-
}
-
-
private View getSwipeMenuView(View itemView) {
-
if (itemView instanceof SwipeMenuLayout) return itemView;
-
List<View> unvisited = new ArrayList<>();
-
unvisited.add(itemView);
-
while (!unvisited.isEmpty()) {
-
View child = unvisited.remove(0);
-
if (!(child instanceof ViewGroup)) { // view
-
continue;
-
}
-
if (child instanceof SwipeMenuLayout) return child;
-
ViewGroup group = (ViewGroup) child;
-
final int childCount = group.getChildCount();
-
for (int i = 0; i < childCount; i++) unvisited.add(group.getChildAt(i));
-
}
-
return itemView;
-
}
-
-
private int mScrollState = -1;
-
-
private boolean isLoadMore = false;
-
private boolean isAutoLoadMore = true;
-
private boolean isLoadError = false;
-
-
private boolean mDataEmpty = true;
-
private boolean mHasMore = false;
-
-
private LoadMoreView mLoadMoreView;
-
private LoadMoreListener mLoadMoreListener;
-
-
@Override
-
public void onScrollStateChanged(int state) {
-
this.mScrollState = state;
-
}
-
-
@Override
-
public void onScrolled(int dx, int dy) {
-
LayoutManager layoutManager = getLayoutManager();
-
if (layoutManager != null && layoutManager instanceof LinearLayoutManager) {
-
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
-
-
int itemCount = layoutManager.getItemCount();
-
if (itemCount <= 0) return;
-
-
int lastVisiblePosition = linearLayoutManager.findLastVisibleItemPosition();
-
-
if (itemCount == lastVisiblePosition + 1 &&
-
(mScrollState == SCROLL_STATE_DRAGGING || mScrollState == SCROLL_STATE_SETTLING)) {
-
dispatchLoadMore();
-
}
-
} else if (layoutManager != null && layoutManager instanceof StaggeredGridLayoutManager) {
-
StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
-
-
int itemCount = layoutManager.getItemCount();
-
if (itemCount <= 0) return;
-
-
int[] lastVisiblePositionArray = staggeredGridLayoutManager.findLastCompletelyVisibleItemPositions(null);
-
int lastVisiblePosition = lastVisiblePositionArray[lastVisiblePositionArray.length - 1];
-
-
if (itemCount == lastVisiblePosition + 1 &&
-
(mScrollState == SCROLL_STATE_DRAGGING || mScrollState == SCROLL_STATE_SETTLING)) {
-
dispatchLoadMore();
-
}
-
}
-
}
-
-
private void dispatchLoadMore() {
-
if (isLoadError) return;
-
-
if (!isAutoLoadMore) {
-
if (mLoadMoreView != null)
-
mLoadMoreView.onWaitToLoadMore(mLoadMoreListener);
-
} else {
-
if (isLoadMore || mDataEmpty || !mHasMore) return;
-
-
isLoadMore = true;
-
-
if (mLoadMoreView != null)
-
mLoadMoreView.onLoading();
-
-
if (mLoadMoreListener != null)
-
mLoadMoreListener.onLoadMore();
-
}
-
}
-
-
/**
-
* Use the default to load more View.
-
*/
-
public void useDefaultLoadMore() {
-
DefaultLoadMoreView defaultLoadMoreView = new DefaultLoadMoreView(getContext());
-
addFooterView(defaultLoadMoreView);
-
setLoadMoreView(defaultLoadMoreView);
-
}
-
-
/**
-
* Load more view.
-
*/
-
public void setLoadMoreView(LoadMoreView loadMoreView) {
-
mLoadMoreView = loadMoreView;
-
}
-
-
/**
-
* Load more listener.
-
*/
-
public void setLoadMoreListener(LoadMoreListener loadMoreListener) {
-
mLoadMoreListener = loadMoreListener;
-
}
-
-
/**
-
* Automatically load more automatically.
-
* <p>
-
* Non-auto-loading mode, you can to click on the item to load.
-
* </p>
-
*
-
* @param autoLoadMore you can use false.
-
* @see LoadMoreView#onWaitToLoadMore(LoadMoreListener)
-
*/
-
public void setAutoLoadMore(boolean autoLoadMore) {
-
isAutoLoadMore = autoLoadMore;
-
}
-
-
/**
-
* Load more done.
-
*
-
* @param dataEmpty data is empty ?
-
* @param hasMore has more data ?
-
*/
-
public final void loadMoreFinish(boolean dataEmpty, boolean hasMore) {
-
isLoadMore = false;
-
isLoadError = false;
-
-
mDataEmpty = dataEmpty;
-
mHasMore = hasMore;
-
-
if (mLoadMoreView != null) {
-
mLoadMoreView.onLoadFinish(dataEmpty, hasMore);
-
}
-
}
-
-
/**
-
* Called when data is loaded incorrectly.
-
*
-
* @param errorCode Error code, will be passed to the LoadView, you can according to it to customize the prompt information.
-
* @param errorMessage Error message.
-
*/
-
public void loadMoreError(int errorCode, String errorMessage) {
-
isLoadMore = false;
-
isLoadError = true;
-
-
if (mLoadMoreView != null) {
-
mLoadMoreView.onLoadError(errorCode, errorMessage);
-
}
-
}
-
-
public interface LoadMoreView {
-
-
/**
-
* Show progress.
-
*/
-
void onLoading();
-
-
/**
-
* Load finish, handle result.
-
*/
-
void onLoadFinish(boolean dataEmpty, boolean hasMore);
-
-
/**
-
* Non-auto-loading mode, you can to click on the item to load.
-
*/
-
void onWaitToLoadMore(LoadMoreListener loadMoreListener);
-
-
/**
-
* Load error.
-
*/
-
void onLoadError(int errorCode, String errorMessage);
-
}
-
-
public interface LoadMoreListener {
-
-
/**
-
* More data should be requested.
-
*/
-
void onLoadMore();
-
}
-
-
}
我们在上述自定义RecyclerView的源码里搜索onLoadMore，发现是在dispatchLoadMore函数里调用了，好的，然后我们再搜索dispatchLoadMore是在哪里被调用了，发现是在RecyclerView的这个系统函数里调用的：
-
@Override
-
public void onScrolled(int dx, int dy) {
-
LayoutManager layoutManager = getLayoutManager();
-
if (layoutManager != null && layoutManager instanceof LinearLayoutManager) {
-
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
-
-
int itemCount = layoutManager.getItemCount();
-
if (itemCount <= 0) return;
-
-
int lastVisiblePosition = linearLayoutManager.findLastVisibleItemPosition();
-
-
if (itemCount == lastVisiblePosition + 1 &&
-
(mScrollState == SCROLL_STATE_DRAGGING || mScrollState == SCROLL_STATE_SETTLING)) {
-
dispatchLoadMore();
-
}
-
} ......
onScrolled这个函数是在RecyclerView控件滚动回调的。它有两个参数dx:水平滚动的距离，dy垂直滚动的距离，当然这里判断是否滚动到列表页底部不是用这两个参数判断的，在这里我们只是顺便提一下。主要是用下面这个if判断来判断页面是否滚动到了底部：
int lastVisiblePosition = linearLayoutManager.findLastVisibleItemPosition();
-
if (itemCount == lastVisiblePosition + 1 &&
-
(mScrollState == SCROLL_STATE_DRAGGING || mScrollState == SCROLL_STATE_SETTLING)) {
-
dispatchLoadMore();
-
}
当可见列表项的位置为最后一个列表项，且列表滚动状态为 DRAGGING（手指拖曳滚动）时 或 SCROLL_STATE_SETTING（列表惯性滚动）时，调用dispatchLoadMore()函数，从而调用了loadMore上拉加载函数，由于loadMore是在DefaultActivity（显示RecyclerView控件的主页面）里实现的接口函数，因此请求网络数据的代码在以下这个函数里处理的：
-
/**
-
* 加载更多。
-
*/
-
private SwipeMenuRecyclerView.LoadMoreListener mLoadMoreListener = new SwipeMenuRecyclerView.LoadMoreListener() {
-
@Override
-
public void onLoadMore() {
-
mRecyclerView.postDelayed(new Runnable() {
-
@Override
-
public void run() {
-
List<String> strings = createDataList(mAdapter.getItemCount());
-
mDataList.addAll(strings);
-
// notifyItemRangeInserted()或者notifyDataSetChanged().
-
mAdapter.notifyItemRangeInserted(mDataList.size() - strings.size(), strings.size());
-
-
// 数据完更多数据，一定要掉用这个方法。
-
// 第一个参数：表示此次数据是否为空。
-
// 第二个参数：表示是否还有更多数据。
-
mRecyclerView.loadMoreFinish(false, true);
-
-
// 如果加载失败调用下面的方法，传入errorCode和errorMessage。
-
// errorCode随便传，你自定义LoadMoreView时可以根据errorCode判断错误类型。
-
// errorMessage是会显示到loadMoreView上的，用户可以看到。
-
// mRecyclerView.loadMoreError(0, "请求网络失败");
-
}
-
}, 1000);
-
}
-
};
这个函数里我们模拟了列表数据的增加。
OK，至此下拉加载更多的原理和过程也就分析完了。我们来总结以下：
（1）上拉刷新，使用系统SwipeRefreshLayout控件就可以实现，无需自定义代码。
（2）下拉加载更多，需要扩展RecyclerView,并重写onScrolled函数，在滑动页面底部的时候调用dispatchLoadMore()---onLoadMore();
最后点击 源码
文章来源: blog.csdn.net，作者：冉航--小虾米，版权归原作者所有，如需转载，请联系作者。
原文链接：blog.csdn.net/gaoxiaoweiandy/article/details/80963228
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