@ModelAttribute注解

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1.前端页面

index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute</title></head><body><h3>测试@ModelAttribute的不同用法</h3><a href="loginForm1">测试@ModelAttribute(value="")注释返回具体类的方法 </a><br><br><a href="loginForm2">测试@ModelAttribute注释void返回值的方法</a><br><br><a href="loginForm3">测试@ModelAttribute注释返回具体类的方法</a><br><br><a href="loginForm4">测试@ModelAttribute和@RequestMapping同时注释一个方法 </a><br><br><a href="loginForm5">测试@ModelAttribute注释一个方法的参数 </a><br><br></body></html>

loginForm1.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute</title></head><body><h3>测试@ModelAttribute(value="")注释返回具体类的方法</h3><form action="login1" method="post">     <table>         <tr>         <td><label>登录名: </label></td>            <td><input type="text" id="loginname" name="loginname" ></td>         </tr>         <tr>             <td><input id="submit" type="submit" value="登录"></td>         </tr>     </table></form></body></html>

loginForm2.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute</title></head><body><h3>测试@ModelAttribute注释void返回值的方法</h3><form action="login2" method="post">     <table>         <tr>         <td><label>登录名: </label></td>            <td><input type="text" id="loginname" name="loginname" ></td>         </tr>         <tr>         <td><label>密码: </label></td>             <td><input type="password" id="password" name="password"></td>         </tr>         <tr>             <td><input id="submit" type="submit" value="登录"></td>         </tr>     </table></form></body></html>

loginForm3.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute</title></head><body><h3>测试@ModelAttribute注释返回具体类的方法</h3><form action="login3" method="post">     <table>         <tr>         <td><label>登录名: </label></td>            <td><input type="text" id="loginname" name="loginname" ></td>         </tr>         <tr>         <td><label>密码: </label></td>            <td><input type="password" id="password" name="password"></td>         </tr>         <tr>             <td><input id="submit" type="submit" value="登录"></td>         </tr>     </table></form></body></html>

loginForm4.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute</title></head><body><h3>测试@ModelAttribute和@RequestMapping同时注释一个方法</h3><form action="login4" method="post">     <table>         <tr>         <td><label>登录名: </label></td>            <td><input type="text" id="loginname" name="loginname" ></td>         </tr>         <tr>         <td><label>密码: </label></td>            <td><input type="password" id="password" name="password"></td>         </tr>         <tr>             <td><input id="submit" type="submit" value="登录"></td>         </tr>     </table></form></body></html>

loginForm5.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute</title></head><body><h3>测试@ModelAttribute注释一个方法的参数 </h3><form action="login5" method="post">     <table>         <tr>         <td><label>登录名: </label></td>            <td><input type="text" id="loginname" name="loginname" ></td>         </tr>         <tr>         <td><label>密码: </label></td>            <td><input type="password" id="password" name="password"></td>         </tr>         <tr>             <td><input id="submit" type="submit" value="登录"></td>         </tr>     </table></form></body></html>

result1.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute(value="")注释返回具体类的方法</title></head><body>访问request作用范围域中的loginname对象：${requestScope.loginname }<br><br></body></html>

result2.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute注释void返回值的方法</title></head><body>访问request作用范围域中的loginname对象：${requestScope.loginname }<br>访问request作用范围域中的password对象：${requestScope.password }<br><br></body></html>

result3.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute注释返回具体类的方法</title></head><body>访问request作用范围域中的user对象：${requestScope.user.username }<br><br></body></html>

result5.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute注释一个方法的参数</title></head><body>访问request作用范围域中的user对象：${requestScope.user.username }<br><br></body></html>

login4.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>测试@ModelAttribute和@RequestMapping同时注释一个方法</title></head><body>访问request作用范围域中的username对象：${requestScope.username }<br><br></body></html>

2.JavaBean

User.java

package com.bean;import java.io.Serializable;//域对象，实现序列化接口public class User implements Serializable {// 私有字段    private String loginname;private String password;private String username;public User() {super();// TODO Auto-generated constructor stub}public User(String loginname, String password, String username) {super();this.loginname = loginname;this.password = password;this.username = username;}public String getLoginname() {return loginname;}public void setLoginname(String loginname) {this.loginname = loginname;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}}

3.控制类

FormController.java

package com.control;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;/* * 总体控制类 *///Controller注解用于指示该类是一个控制器，可以同时处理多个请求动作@Controllerpublic class FormController { // 该方法映射的请求为http://localhost:8080/ModelAttributeTest/{formName} @RequestMapping(value="/{formName}")public String loginForm(@PathVariable String formName){   // 动态跳转页面   return formName;}}

ModelAttribute1Controller.java

package com.control;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;//Controller注解用于指示该类是一个控制器，可以同时处理多个请求动作@Controllerpublic class ModelAttribute1Controller {// 使用@ModelAttribute注释的value属性，来指定model属性的名称,model属性对象就是方法的返回值@ModelAttribute("loginname")public String userModel1(@RequestParam("loginname") String loginname){return loginname;}@RequestMapping(value="/login1") public String login1() { return "result1"; }}

ModelAttribute2Controller.java

package com.control;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;//Controller注解用于指示该类是一个控制器，可以同时处理多个请求动作@Controllerpublic class ModelAttribute2Controller {// model属性名称和model属性对象由model.addAttribute()实现，前提是要在方法中加入一个Model类型的参数。// 注意：当URL或者post中不包含对应的参数时，程序会抛出异常。@ModelAttributepublic void userModel2(@RequestParam("loginname") String loginname,@RequestParam("password") String password,Model model){model.addAttribute("loginname", loginname);model.addAttribute("password", password);}@RequestMapping(value="/login2") public String login2() { return "result2"; }}

ModelAttribute3Controller.java

package com.control;import java.util.ArrayList;import java.util.List;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;import com.bean.User;//Controller注解用于指示该类是一个控制器，可以同时处理多个请求动作@Controllerpublic class ModelAttribute3Controller {// 静态List<User>集合，此处代替数据库用来保存注册的用户信息private static List<User> userList;    // UserController类的构造器，初始化List<User>集合public ModelAttribute3Controller() {super();userList = new ArrayList<User>();User user1 = new User("test","123456","测试用户");User user2 = new User("admin","123456","管理员");// 存储User用户，用于模拟数据库数据userList.add(user1);userList.add(user2);}// 根据登录名和密码查询用户，用户存在返回包含用户信息的User对象，不存在返回nullpublic User find(String loginname,String password){for(User user: userList){if(user.getLoginname().equals(loginname) && user.getPassword().equals(password)){return user;}}return null;}// model属性的名称没有指定，它由返回类型隐含表示，如这个方法返回User类型，那么这个model属性的名称是user。    // 这个例子中model属性名称由返回对象类型隐含表示，model属性对象就是方法的返回值。它不需要指定特定的参数。@ModelAttributepublic User userModel3(@RequestParam("loginname") String loginname,@RequestParam("password") String password){return find(loginname,password);}@RequestMapping(value="/login3") public String login3() { return "result3";}}

ModelAttribute4Controller.java

package com.control;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.bind.annotation.RequestMapping;//Controller注解用于指示该类是一个控制器，可以同时处理多个请求动作@Controllerpublic class ModelAttribute4Controller {// 这时这个方法的返回值并不是表示一个视图名称，而是model属性的值，视图名称是@RequestMapping的value值。    // Model属性名称由@ModelAttribute(value=””)指定，相当于在request中封装了username（key）=admin（value）。@RequestMapping(value="/login4")@ModelAttribute(value="username")public String login4() { return "admin"; }}

ModelAttribute5Controller.java

package com.control;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;import com.bean.User;//Controller注解用于指示该类是一个控制器，可以同时处理多个请求动作@Controllerpublic class ModelAttribute5Controller {// model属性名称就是value值即”user”，model属性对象就是方法的返回值@ModelAttribute("user")public User userModel5(@RequestParam("loginname") String loginname,@RequestParam("password") String password){User user=new User();user.setLoginname(loginname);user.setPassword(password);return user;}// @ModelAttribute("user") User user注释方法参数，参数user的值来源于userModel5()方法中的model属性。@RequestMapping(value="/login5")public String login5(@ModelAttribute("user") User user){user.setUsername("管理员");return "result5";}}

截图

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