SpringMVC联手REST实现入门级的CRUD

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

首先是web.xml（最终应用访问地址为http://IP:port/contextPath/user/add）

<?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", "[email protected]"));
		users.put("李寻欢", new User("李寻欢", "李探花", "08866659", "[email protected]"));
		users.put("拓拔野", new User("拓拔野", "搜神记", "05577759", "[email protected]"));
		users.put("孙悟空", new User("孙悟空", "美猴王", "03311159", "[email protected]"));
	}
	
	/**
	 * 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
	}
}