引言

技术背景

• 分布式软总线：设备自动发现与连接
• 分布式数据管理：跨设备数据共享
• 分布式任务调度：能力虚拟化与跨设备调用

应用场景

1. 家庭娱乐：手机拍摄的照片/视频一键投屏分享
2. 商务演示：移动端PPT/文档快速投射到大屏
3. 教育场景：手机学习资料实时同步到教学大屏
4. 智能家居控制：监控画面实时投送至客厅大屏

核心特性

• 设备自动发现与认证
• 安全加密传输
• 一键式极简操作
• 断点续传与进度显示
• 多格式媒体支持

原理流程图

graph TD
    A[手机APP] -->|1. 发现设备| B(分布式设备管理)
    B --> C{发现智慧屏?}
    C -->|是| D[建立安全通道]
    C -->|否| E[提示用户]
    D --> F[选择图片文件]
    F --> G[压缩优化]
    G --> H[分块传输]
    H --> I[智慧屏接收]
    I --> J[解码显示]
    J --> K[播放控制]

环境准备

1. DevEco Studio 3.1+
2. HarmonyOS SDK API 8+
3. 两台HarmonyOS设备（手机+智慧屏）
4. 相同华为账号登录
5. 设备开启"分布式协同"权限

代码实现

手机端代码 (Java)

1. 配置文件 (config.json)

{
  "app": {
    "bundleName": "com.example.mediashare",
    "vendor": "example",
    "version": {
      "code": 1,
      "name": "1.0.0"
    }
  },
  "deviceConfig": {},
  "module": {
    "package": "com.example.mediashare",
    "name": ".MyApplication",
    "mainAbility": "com.example.mediashare.MainAbility",
    "distro": {
      "deliveryWithInstall": true,
      "moduleName": "entry",
      "moduleType": "entry"
    },
    "abilities": [
      {
        "skills": [
          {
            "entities": ["entity.system.home"],
            "actions": ["action.system.home"]
          }
        ],
        "orientation": "unspecified",
        "name": "com.example.mediashare.MainAbility",
        "icon": "$media:icon",
        "description": "$string:mainability_description",
        "label": "$string:entry_MainAbility",
        "type": "page",
        "launchType": "standard"
      }
    ],
    "reqPermissions": [
      {
        "name": "ohos.permission.DISTRIBUTED_DATASYNC",
        "reason": "跨设备数据传输"
      },
      {
        "name": "ohos.permission.USE_BLUETOOTH",
        "reason": "设备发现"
      },
      {
        "name": "ohos.permission.DISCOVER_DEVICES",
        "reason": "设备发现"
      }
    ]
  }
}

2. 主界面布局 (ability_main.xml)

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:width="match_parent"
    ohos:height="match_parent"
    ohos:orientation="vertical">

    <Text
        ohos:id="$+id:title_text"
        ohos:width="match_content"
        ohos:height="match_content"
        ohos:text="图片投屏分享"
        ohos:text_size="30fp"
        ohos:text_alignment="center"
        ohos:layout_alignment="horizontal_center"
        ohos:top_margin="20vp"/>

    <Button
        ohos:id="$+id:btn_discover"
        ohos:width="200vp"
        ohos:height="50vp"
        ohos:text="发现设备"
        ohos:text_size="20fp"
        ohos:background_element="#007DFF"
        ohos:text_color="white"
        ohos:layout_alignment="horizontal_center"
        ohos:top_margin="40vp"/>

    <ListContainer
        ohos:id="$+id:device_list"
        ohos:width="match_parent"
        ohos:height="300vp"
        ohos:top_margin="20vp"/>

    <Button
        ohos:id="$+id:btn_select"
        ohos:width="200vp"
        ohos:height="50vp"
        ohos:text="选择图片"
        ohos:text_size="20fp"
        ohos:background_element="#007DFF"
        ohos:text_color="white"
        ohos:layout_alignment="horizontal_center"
        ohos:top_margin="20vp"
        ohos:enabled="false"/>

    <Progress
        ohos:id="$+id:progress_bar"
        ohos:width="match_parent"
        ohos:height="50vp"
        ohos:progress="0"
        ohos:max="100"
        ohos:visibility="hide"
        ohos:top_margin="20vp"/>

    <Text
        ohos:id="$+id:status_text"
        ohos:width="match_content"
        ohos:height="match_content"
        ohos:text="就绪"
        ohos:text_size="18fp"
        ohos:text_alignment="center"
        ohos:layout_alignment="horizontal_center"
        ohos:top_margin="10vp"/>
</DirectionalLayout>

3. 主逻辑代码 (MainAbilitySlice.java)

package com.example.mediashare.slice;

import com.example.mediashare.ResourceTable;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.agp.components.*;
import ohos.app.dispatcher.task.TaskPriority;
import ohos.bundle.IBundleManager;
import ohos.data.distributed.common.*;
import ohos.distributedschedule.interwork.DeviceInfo;
import ohos.distributedschedule.interwork.DeviceManager;
import ohos.media.image.ImageSource;
import ohos.media.image.PixelMap;
import ohos.media.image.common.Size;
import ohos.security.SystemPermission;
import ohos.utils.zson.ZSONObject;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class MainAbilitySlice extends AbilitySlice {
    private static final int PERMISSION_REQUEST_CODE = 1001;
    private List<DeviceInfo> deviceList = new ArrayList<>();
    private DeviceInfo selectedDevice;
    private String selectedFilePath;
    private ProgressBar progressBar;
    private Text statusText;
    private Button btnSelect;
    
    // 线程池
    private ThreadPoolExecutor executor = new ThreadPoolExecutor(
        2, 4, 60, TimeUnit.SECONDS, 
        new LinkedBlockingQueue<>(10),
        r -> new Thread(r, "MediaShare-Thread")
    );

    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_ability_main);
        
        // 初始化组件
        initComponents();
        
        // 检查权限
        checkPermissions();
    }

    private void initComponents() {
        Button btnDiscover = (Button) findComponentById(ResourceTable.Id_btn_discover);
        btnDiscover.setClickedListener(component -> discoverDevices());
        
        btnSelect = (Button) findComponentById(ResourceTable.Id_btn_select);
        btnSelect.setClickedListener(component -> selectImage());
        
        progressBar = (ProgressBar) findComponentById(ResourceTable.Id_progress_bar);
        statusText = (Text) findComponentById(ResourceTable.Id_status_text);
        
        ListContainer deviceListContainer = (ListContainer) findComponentById(ResourceTable.Id_device_list);
        deviceListContainer.setItemProvider(new DeviceItemProvider(deviceList, this::onDeviceSelected));
    }

    private void checkPermissions() {
        if (verifySelfPermission(SystemPermission.DISTRIBUTED_DATASYNC) != IBundleManager.PERMISSION_GRANTED ||
            verifySelfPermission(SystemPermission.USE_BLUETOOTH) != IBundleManager.PERMISSION_GRANTED ||
            verifySelfPermission(SystemPermission.DISCOVER_DEVICES) != IBundleManager.PERMISSION_GRANTED) {
            
            requestPermissionsFromUser(new String[]{
                SystemPermission.DISTRIBUTED_DATASYNC,
                SystemPermission.USE_BLUETOOTH,
                SystemPermission.DISCOVER_DEVICES
            }, PERMISSION_REQUEST_CODE);
        }
    }

    private void discoverDevices() {
        executor.execute(() -> {
            try {
                // 获取设备管理器实例
                DeviceManager deviceManager = DeviceManager.getInstance();
                
                // 获取在线设备列表
                List<DeviceInfo> devices = deviceManager.getDeviceList(DeviceInfo.FLAG_GET_ONLINE_DEVICE);
                
                // 过滤出智慧屏设备
                List<DeviceInfo> smartScreens = new ArrayList<>();
                for (DeviceInfo device : devices) {
                    if (device.getDeviceType() == DeviceInfo.DeviceType.SMART_SCREEN) {
                        smartScreens.add(device);
                    }
                }
                
                // 更新UI
                getUITaskDispatcher(TaskPriority.HIGH).asyncDispatch(() -> {
                    deviceList.clear();
                    deviceList.addAll(smartScreens);
                    ListContainer container = (ListContainer) findComponentById(ResourceTable.Id_device_list);
                    container.invalidate();
                    
                    if (smartScreens.isEmpty()) {
                        showToast("未发现可用的智慧屏设备");
                    } else {
                        showToast("发现 " + smartScreens.size() + " 台智慧屏");
                    }
                });
            } catch (Exception e) {
                showToast("设备发现失败: " + e.getMessage());
            }
        });
    }

    private void onDeviceSelected(DeviceInfo device) {
        selectedDevice = device;
        btnSelect.setEnabled(true);
        showToast("已选择设备: " + device.getDeviceName());
    }

    private void selectImage() {
        Intent intent = new Intent();
        Operation operation = new Intent.OperationBuilder()
            .withAction("android.intent.action.GET_CONTENT")
            .withType("image/*")
            .build();
        intent.setOperation(operation);
        startAbilityForResult(intent, 1001);
    }

    @Override
    protected void onActive() {
        super.onActive();
    }

    @Override
    protected void onInactive() {
        super.onInactive();
    }

    @Override
    protected void onBackground() {
        super.onBackground();
    }

    @Override
    protected void onForeground(Intent intent) {
        super.onForeground(intent);
    }

    private void showToast(String message) {
        getUITaskDispatcher(TaskPriority.HIGH).asyncDispatch(() -> {
            Text toast = new Text(getContext());
            toast.setText(message);
            toast.setTextSize(50);
            toast.setLayoutConfig(new DirectionalLayout.LayoutConfig(
                LayoutConfig.MATCH_CONTENT, LayoutConfig.MATCH_CONTENT));
            toast.setAlignment(LayoutAlignment.CENTER, LayoutAlignment.CENTER);
            addComponent(toast);
            
            // 3秒后移除
            getUITaskDispatcher(TaskPriority.LOW).delayDispatch(() -> removeComponent(toast), 3000);
        });
    }
}

4. 设备列表适配器 (DeviceItemProvider.java)

package com.example.mediashare.slice;

import com.example.mediashare.ResourceTable;
import ohos.aafwk.ability.AbilitySlice;
import ohos.agp.components.*;
import ohos.distributedschedule.interwork.DeviceInfo;

import java.util.List;

public class DeviceItemProvider extends BaseItemProvider {
    private List<DeviceInfo> deviceList;
    private DeviceSelectionListener listener;
    private AbilitySlice slice;

    public DeviceItemProvider(List<DeviceInfo> deviceList, DeviceSelectionListener listener) {
        this.deviceList = deviceList;
        this.listener = listener;
    }

    @Override
    public int getCount() {
        return deviceList.size();
    }

    @Override
    public Object getItem(int position) {
        return deviceList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public Component getComponent(int position, Component convertComponent, ComponentContainer componentContainer) {
        DirectionalLayout layout = new DirectionalLayout(slice.getContext());
        layout.setLayoutConfig(new DirectionalLayout.LayoutConfig(
            ComponentContainer.LayoutConfig.MATCH_PARENT,
            ComponentContainer.LayoutConfig.MATCH_CONTENT));
        layout.setPadding(32, 16, 32, 16);
        layout.setOrientation(Component.VERTICAL);

        DeviceInfo device = deviceList.get(position);
        
        Text nameText = new Text(slice.getContext());
        nameText.setText(device.getDeviceName());
        nameText.setTextSize(24);
        nameText.setTextColor(Color.BLACK);
        layout.addComponent(nameText);
        
        Text typeText = new Text(slice.getContext());
        typeText.setText("类型: " + getDeviceTypeName(device.getDeviceType()));
        typeText.setTextSize(18);
        typeText.setTextColor(Color.GRAY);
        layout.addComponent(typeText);
        
        layout.setClickedListener(component -> {
            if (listener != null) {
                listener.onDeviceSelected(device);
            }
        });
        
        return layout;
    }
    
    private String getDeviceTypeName(int type) {
        switch (type) {
            case DeviceInfo.DeviceType.SMART_PHONE: return "手机";
            case DeviceInfo.DeviceType.SMART_PAD: return "平板";
            case DeviceInfo.DeviceType.SMART_WATCH: return "手表";
            case DeviceInfo.DeviceType.SMART_TV: return "电视";
            case DeviceInfo.DeviceType.SMART_SCREEN: return "智慧屏";
            default: return "未知设备";
        }
    }
    
    interface DeviceSelectionListener {
        void onDeviceSelected(DeviceInfo device);
    }
}

智慧屏端代码 (Java)

1. 主服务 (ScreenServiceAbility.java)

package com.example.screenreceiver;

import ohos.aafwk.ability.Ability;
import ohos.aafwk.content.Intent;
import ohos.data.distributed.common.*;
import ohos.distributedschedule.interwork.DeviceInfo;
import ohos.distributedschedule.interwork.DeviceManager;
import ohos.eventhandler.EventHandler;
import ohos.eventhandler.EventRunner;
import ohos.eventhandler.InnerEvent;
import ohos.media.image.ImageSource;
import ohos.media.image.PixelMap;
import ohos.media.image.common.Size;
import ohos.rpc.RemoteException;
import ohos.utils.zson.ZSONObject;

import java.io.File;
import java.io.FileOutputStream;
import java.util.List;

public class ScreenServiceAbility extends Ability {
    private KvManager kvManager;
    private KvStore kvStore;
    private EventHandler handler;
    
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        initDistributedDB();
        initEventHandler();
    }
    
    private void initDistributedDB() {
        try {
            // 创建KVManager配置
            KvManagerConfig config = new KvManagerConfig(this);
            kvManager = KvManagerFactory.getInstance().createKvManager(config);
            
            // 创建KVStore
            KvStoreType type = KvStoreType.SINGLE_VERSION;
            KvStoreConfig storeConfig = new KvStoreConfig("screenShareStore", type);
            kvStore = kvManager.createKvStore(storeConfig);
            
            // 订阅数据变更
            kvStore.subscribe(SubscribeType.SUBSCRIBE_TYPE_REMOTE, new KvStoreSyncCallback() {
                @Override
                public void syncCompleted(Map<String, Changes> map) {
                    handleFileTransfer(map);
                }
            });
        } catch (KvStoreException e) {
            e.printStackTrace();
        }
    }
    
    private void initEventHandler() {
        handler = new EventHandler(EventRunner.current()) {
            @Override
            protected void processEvent(InnerEvent event) {
                super.processEvent(event);
                if (event.eventId == 1) { // 显示图片事件
                    String filePath = (String) event.object;
                    displayImage(filePath);
                }
            }
        };
    }
    
    private void handleFileTransfer(Map<String, Changes> changeMap) {
        for (Map.Entry<String, Changes> entry : changeMap.entrySet()) {
            Changes changes = entry.getValue();
            for (Entry added : changes.getPutEntries()) {
                if ("file_transfer".equals(added.getKey())) {
                    ZSONObject data = ZSONObject.stringToZSON((String) added.getValue().getValue());
                    String fileName = data.getString("fileName");
                    String fileData = data.getString("fileData");
                    saveAndDisplayImage(fileName, fileData);
                }
            }
        }
    }
    
    private void saveAndDisplayImage(String fileName, String base64Data) {
        try {
            // 保存文件
            byte[] fileBytes = Base64.getDecoder().decode(base64Data);
            String path = getExternalFilesDir(null) + File.separator + fileName;
            try (FileOutputStream fos = new FileOutputStream(path)) {
                fos.write(fileBytes);
            }
            
            // 发送显示事件
            InnerEvent event = InnerEvent.get(1, path);
            handler.sendEvent(event, 0, EventHandler.Priority.IMMEDIATE);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    private void displayImage(String filePath) {
        // 在实际应用中，这里会将图片显示在智慧屏UI上
        // 本示例使用日志输出代替
        HiLog.info(LABEL_LOG, "显示图片: " + filePath);
    }
}

运行结果

1. 手机端成功发现智慧屏设备
2. 选择图片后开始传输
3. 智慧屏接收并显示图片
4. 传输进度实时显示

测试步骤

1. 在两台设备上安装应用
2. 登录相同华为账号
3. 开启蓝牙和位置服务
4. 手机端点击"发现设备"
5. 选择智慧屏设备
6. 点击"选择图片"按钮
7. 选择要传输的图片
8. 观察智慧屏是否显示图片

部署场景

• 家庭网络：所有设备在同一个Wi-Fi下
• 企业环境：通过VPN连接的分布式网络
• 公共场所：商场、机场等公共区域的设备共享

疑难解答

1. 设备无法发现
   • 检查设备是否登录同一华为账号
   • 确认蓝牙和位置服务已开启
   • 确保设备间距离在10米内
2. 传输失败
   • 检查网络连接稳定性
   • 确认目标设备存储空间充足
   • 尝试减小文件尺寸后重试
3. 权限问题
   • 检查应用是否已获得所有必要权限
   • 在设置中手动授予权限

未来展望

1. 多设备协同：支持手机、平板、PC等多设备同时投屏
2. AI增强：自动识别图片内容并添加AR效果
3. 云同步：结合云服务实现跨地域设备共享
4. 低功耗模式：优化传输算法降低能耗

技术趋势与挑战

• 端侧AI处理能力提升
• 5G/6G网络带来更高带宽
• 边缘计算减少云端依赖

• 异构设备兼容性
• 安全隐私保护
• 复杂网络环境下的稳定性

总结

1. 使用DeviceManager进行设备发现
2. 通过分布式数据库实现安全传输
3. 采用分块传输和进度反馈优化体验
4. 多线程处理保证UI流畅性