SpringMVC教程/实例(三)：java SpringMVC之REST实现简单的增删改查CRUD

这是一个WebProject，用到的是spring-framework-3.1.1.RELEASE

首先是web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet>
<servlet-name>user</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>user</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

<filter>
<filter-name>SpringCharacterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>SpringCharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>

然后是SpringMVC的配置文件user-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <context:component-scan base-package="com.jadyer"/>

<mvc:annotation-driven/>

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/"/>
<property name="suffix" value=".jsp"/>
</bean>
</beans>

用来添加用户信息的//WEB-INF//jsp/user/add.jsp

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>

<%-- 这里并没有指定action=""，说明表单是提交给自己的，说白了就是"哪来的回哪儿去 --%>

<form:form method="POST" modelAttribute="user">
username: <form:input path="username"/><br/>
nickname: <form:input path="nickname"/><br/>
password: <form:password path="password"/><br/>
yourmail: <form:input path="email"/><br/>
<input type="submit" value="添加新用户"/>
</form:form>

用来列出所有用户信息的//WEB-INF//jsp/user/list.jsp

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<c:forEach items="${users}" var="user">
${user.value.username}----${user.value.nickname}----${user.value.password}----${user.value.email}
<a href="<%=request.getContextPath()%>/user/${user.value.username}">查看</a>
<a href="<%=request.getContextPath()%>/user/${user.value.username}/update">编辑</a>
<a href="<%=request.getContextPath()%>/user/${user.value.username}/delete">删除</a>
<br/>
</c:forEach>
<br/>
<a href="<%=request.getContextPath()%>/user/add">继续添加用户</a>

用来显示单个用户信息的//WEB-INF//jsp/user/show.jsp

<%@ page language="java" pageEncoding="UTF-8"%>
${user.username}----${user.nickname}----${user.password}----${user.email}
<br/>
<br/>
<a href="<%=request.getContextPath()%>/user/add">继续添加用户</a>

用来更新单个用户信息的//WEB-INF//jsp/user/update.jsp

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<form:form method="POST" modelAttribute="user">
username: <form:input path="username"/><br/>
nickname: <form:input path="nickname"/><br/>
password: <form:password path="password"/><br/>
yourmail: <form:input path="email"/><br/>
<input type="submit" value="更新用户信息"/>
</form:form>

下面是用户的实体类User.java

package com.jadyer.model;

/**
* User
* @author http://blog.csdn.net/jadyer * @create May 12, 2012 1:24:43 AM
*/
public class User {
private String username;
private String nickname;
private String password;
private String email;

public User() {}
public User(String username, String nickname, String password, String email) {
this.username = username;
this.nickname = nickname;
this.password = password;
this.email = email;
}

public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getNickname() {
return nickname;
}
public void setNickname(String nickname) {
this.nickname = nickname;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}

最后是核心的UserController.java

package com.jadyer.controller;

import java.util.HashMap;
import java.util.Map;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.jadyer.model.User;

/**
* UserController
* @author http://blog.csdn.net/jadyer * @create May 12, 2012 1:26:21 AM
*/
@Controller
@RequestMapping("/user")
public class UserController {
private final static Map<String,User> users = new HashMap<String,User>();

//模拟数据源,构造初始数据
public UserController(){
users.put("张起灵", new User("张起灵", "闷油瓶", "02200059", "menyouping@yeah.net"));
users.put("李寻欢", new User("李寻欢", "李探花", "08866659", "lixunhuan@gulong.cn"));
users.put("拓拔野", new User("拓拔野", "搜神记", "05577759", "tuobaye@manhuang.cc"));
users.put("孙悟空", new User("孙悟空", "美猴王", "03311159", "sunhouzi@xiyouji.zh"));
}

/**
* 添加新用户
* @see 访问/user/add时，GET请求就执行addUser(Model model)方法，POST请求就执行addUser(User user)方法
*/
@RequestMapping(value="/add", method=RequestMethod.GET)
public String addUser(Model model){
//这里要传给前台一个空对象，否则会报告java.lang.IllegalStateException异常
//异常信息为Neither BindingResult nor plain target object for bean name 'user' available as request attribute
//并且传过去的key值要与前台modelAttribute属性值相同，即model.addAttribute("user", new User());
//我们也可以写成下面这种方式，此时SpringMVC会自动把对象名转换为小写值作为key，即User-->user
model.addAttribute(new User());
return "user/add";
}
@RequestMapping(value="/add", method=RequestMethod.POST)
public String addUser(User user){ //这里参数中的user就应该与add.jsp中的modelAttribute="user"一致了
users.put(user.getUsername(), user);
return "redirect:/user/list";
}

/**
* 列出所有用户信息
*/
@RequestMapping("/list")
public String list(Model model){
model.addAttribute("users", users);
return "user/list";
}

/**
* 查询用户信息
* @see 访问该方法的路径就应该是"/user/具体的用户名"
* @see 这里value="/{username}"的写法，需要格外注意一下，它是一个路径变量，此时用来接收前台的一个资源
* @see 这时value="/{username}"就会到方法参数中找@PathVariable String username，并将路径变量值传给username参数
*/
@RequestMapping(value="/{myname}", method=RequestMethod.GET)
public String show(@PathVariable String myname, Model model){
model.addAttribute(users.get(myname));
return "user/show";
}

/**
* 编辑用户信息
* @see 访问该方法的路径就应该是"/user/具体的用户名/update"
*/
@RequestMapping(value="/{myname}/update", method=RequestMethod.GET)
public String update(@PathVariable String myname, Model model){
model.addAttribute(users.get(myname));
return "user/update";
}
@RequestMapping(value="/{myname}/update", method=RequestMethod.POST)
public String update(User user){
users.put(user.getUsername(), user);
return "redirect:/user/list"; //也可以retun "forward:/user/list",此时浏览器地址栏会有不同
}

/**
* 删除用户信息
*/
@RequestMapping(value="/{myname}/delete", method=RequestMethod.GET)
public String delete(@PathVariable String myname){
users.remove(myname);
return "redirect:/user/list"; //删除完成后显示当前存在的所有用户信息
}
}