spring mvc 模拟数据库实现注册 登录
【摘要】
model层代码，用户
package com.entity;import java.io.Serializable; public class User implements Serializable { //私有字段; private String username; private String pwd; public Stri...
model层代码，用户
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package com.entity;
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import java.io.Serializable;
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public class User implements Serializable {
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//私有字段;
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private String username;
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private String pwd;
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public String getUsername() {
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return username;
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}
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public void setUsername(String username) {
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this.username = username;
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}
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public String getPwd() {
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return pwd;
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}
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public void setPwd(String pwd) {
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this.pwd = pwd;
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}
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}
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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
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<%
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String path = request.getContextPath();
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String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
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%>
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<base href="<%=basePath%>">
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<title>My JSP 'zhuce.jsp' starting page</title>
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<meta http-equiv="pragma" content="no-cache">
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<meta http-equiv="cache-control" content="no-cache">
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<meta http-equiv="expires" content="0">
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<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
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<meta http-equiv="description" content="This is my page">
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</head>
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<body>
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注册页面
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<form action="reg" method="post">
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账户：<input type="text" name="username"/><br/>
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密码：<input type="password" name="pwd"/><br/>
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<input type="submit" value="注册"/>
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</form>
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</body>
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</html>
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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
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<%
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String path = request.getContextPath();
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String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
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%>
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<base href="<%=basePath%>">
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<title>My JSP 'login.jsp' starting page</title>
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<meta http-equiv="pragma" content="no-cache">
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<meta http-equiv="cache-control" content="no-cache">
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<meta http-equiv="expires" content="0">
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<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
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<meta http-equiv="description" content="This is my page">
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</head>
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<body>
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用户登录
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<form action="login" method="post">
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账户：<input type="text" name="username"/><br/>
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密码：<input type="password" name="pwd"/><br/>
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<input type="submit" value="登录"/>
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</form>
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</body>
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</html>
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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
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<%@ page isELIgnored="false" %>
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<%
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String path = request.getContextPath();
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String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
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%>
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<base href="<%=basePath%>">
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<title>My JSP 'welcome.jsp' starting page</title>
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<meta http-equiv="pragma" content="no-cache">
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<meta http-equiv="cache-control" content="no-cache">
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<meta http-equiv="expires" content="0">
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<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
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<meta http-equiv="description" content="This is my page">
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</head>
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<body>
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用户： ${user.username }<br/>
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密码:${user.pwd }
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</body>
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</html>
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package com.controller;
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import java.util.ArrayList;
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import java.util.List;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import org.springframework.stereotype.Controller;
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//import org.springframework.ui.Model;
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import org.springframework.web.bind.annotation.RequestMapping;
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import org.springframework.web.bind.annotation.RequestMethod;
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import org.springframework.web.bind.annotation.RequestParam;
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import org.springframework.web.servlet.ModelAndView;
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import com.entity.User;
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//注解该类是一个控制器，可以同时接受多个请求动作;
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@Controller
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public class UserController {
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//静态List<User>集合，用来代替数据库来保存注册的用户信息;
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private static List<User>userList;
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//UserController类的构造器，初始化List<User>集合
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public UserController() {
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super();
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userList=new ArrayList<User>();
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}
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//静态的日志类;logFactory
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//该方法，请求.../reg,该方法支持Post请求
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@RequestMapping(value="/reg",method=RequestMethod.GET)
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public String regForm(){
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//跳转到注册页面;
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return "zhuce";
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}
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//该方法映射的请求为.../reg,支持Post请求
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@RequestMapping(value="/reg",method=RequestMethod.POST)
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public String register(
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@RequestParam("username")String username,
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@RequestParam("pwd")String pwd ){
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//创建User对象;
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User u=new User();
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u.setUsername(username);
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u.setPwd(pwd);
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//模拟数据存储到数据库user里面
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userList.add(u);
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//跳转到登录页面
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return "login";
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}
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//该方法映射的请求是.../login
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@RequestMapping("/login")
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public ModelAndView login(@RequestParam("username")String username,
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@RequestParam("pwd")String pwd,ModelAndView mv){
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//RequestParam将请求中的username和pwd参数赋值给username，pwd变量。
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//到集合中去查找下用户是否存在，此处用来模拟数据库验证。
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for(User user:userList){
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if(user.getUsername().equals(username)&&user.getPwd().equals(pwd)){
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mv.addObject("user",user);
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mv.setViewName("welcome");
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//mv.addAttribute("user",user);model传递的是requestScope
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return mv;
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}
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}
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return mv;
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}
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}
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<?xml version="1.0" encoding="UTF-8"?>
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<web-app version="2.5"
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xmlns="http://java.sun.com/xml/ns/javaee"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
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http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
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<welcome-file-list>
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<welcome-file>index.jsp</welcome-file>
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</welcome-file-list>
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<servlet>
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<servlet-name>hello</servlet-name>
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<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
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<init-param>
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<param-name>contextConfigLocation</param-name>
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<param-value>WEB-INF/spring-servlet.xml</param-value>
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</init-param>
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<load-on-startup>1</load-on-startup>
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</servlet>
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<servlet-mapping>
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<servlet-name>hello</servlet-name>
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<url-pattern>/</url-pattern>
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</servlet-mapping>
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<filter>
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<filter-name>encodingFilter</filter-name>
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<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
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<init-param>
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<param-name>encoding</param-name>
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<param-value>UTF-8</param-value>
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</init-param>
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</filter>
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<filter-mapping>
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<filter-name>encodingFilter</filter-name>
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<url-pattern>/*</url-pattern>
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</filter-mapping>
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</web-app>
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<?xml version="1.0" encoding="UTF-8"?>
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<beans
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xmlns="http://www.springframework.org/schema/beans"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xmlns:p="http://www.springframework.org/schema/p"
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xmlns:context="http://www.springframework.org/schema/context"
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xmlns:mvc="http://www.springframework.org/schema/mvc"
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xsi:schemaLocation="http://www.springframework.org/schema/beans
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http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
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http://www.springframework.org/schema/context
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http://www.springframework.org/schema/context/spring-context-3.0.xsd
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http://www.springframework.org/schema/mvc
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http://www.springframework.org/schema/mvc/spring-mvc.xsd">
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<context:annotation-config></context:annotation-config>
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<context:component-scan base-package="com"></context:component-scan>
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<!-- ViewResolver -->
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<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
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<property name="viewClass" value="org.springframework.web.servlet.view.JstlView"></property>
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<property name="prefix" value="/"></property>
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<property name="suffix" value=".jsp"></property>
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</bean>
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<!-- <bean name="/hello" class="com.controller.HelloController"></bean>-->
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</beans>
在后续讲课中添加了删除 修改 查询功能，针对删除报错如下：java.util.ConcurrentModificationException异常.
对Vector、ArrayList在迭代的时候如果同时对其进行修改就会抛出java.util.ConcurrentModificationException异常。下面我们就来讨论以下这个异常出现的原因以及解决办法。
单线程环境下的解决办法
public class Test {
public static void main(String[] args) {
ArrayList<Integer> list = new ArrayList<Integer>();
list.add( 2 );
Iterator<Integer> iterator = list.iterator();
while (iterator.hasNext()){
Integer integer = iterator.next();
if (integer== 2 )
iterator.remove(); //注意这个地方
}
}
}
在多线程环境下的解决方法
1）在使用iterator迭代的时候使用synchronized或者Lock进行同步；
2）使用并发容器CopyOnWriteArrayList代替ArrayList和Vector。
文章来源: aaaedu.blog.csdn.net，作者：tea_year，版权归原作者所有，如需转载，请联系作者。
原文链接：aaaedu.blog.csdn.net/article/details/70036826
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