SpringMVC中的異常處理

這是個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><welcome-file-list><welcome-file>/WEB-INF/jsp/login.jsp</welcome-file></welcome-file-list></web-app>

然後是SpringMVC的設定檔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.xsdhttp://www.springframework.org/schema/mvchttp://www.springframework.org/schema/mvc/spring-mvc-3.1.xsdhttp://www.springframework.org/schema/contexthttp://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>

下面是使用者登入頁面//WEB-INF//jsp//login.jsp

<%@ page language="java" pageEncoding="UTF-8"%><form action="<%=request.getContextPath()%>/user/login" method="POST">username: <input type="text" name="username"/><br/>password: <input type="password" name="password"/><br/><input type="submit" value="登入"/></form>

下面是使用者登入失敗頁面//WEB-INF//jsp//error.jsp

<%@ page language="java" pageEncoding="UTF-8"%>${myex.message}

下面是使用者登入成功頁面//WEB-INF//jsp//user//loginSuccess.jsp

<%@ page language="java" pageEncoding="UTF-8"%>welcome: ${loginUser.nickname}

接下來是用到的實體類User.java

package com.jadyer.model;/** * User * @author 宏宇 * @create May 12, 2012 1:24:43 AM */public class User {private String username;private String nickname;private String password;private String email;/*==四個屬性的getter()、setter()略==*/public User() {}public User(String username, String nickname, String password, String email) {this.username = username;this.nickname = nickname;this.password = password;this.email = email;}}

然後是自訂的異常類UserException.java

package com.jadyer.exception;/** * UserException * @author http://blog.csdn/net/jadyer * @create May 12, 2012 6:43:29 PM */@SuppressWarnings("serial")public class UserException extends RuntimeException {public UserException() {super();}public UserException(String message, Throwable cause) {super(message, cause);}public UserException(String message) {super(message);}public UserException(Throwable cause) {super(cause);}}

最後是核心的UserController.java

package com.jadyer.controller;import java.util.HashMap;import java.util.Map;import javax.servlet.http.HttpServletRequest;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.SessionAttributes;import com.jadyer.exception.UserException;import com.jadyer.model.User;/** * SpringMVC中的異常處理方式 * @see 第一步:建立自訂異常類 * @see 第二步:在Controller中建立一個用於截獲並處理異常方法，方法名可隨意 *            然後在方法上標註@ExceptionHandler(你的自訂異常類名.class) *            接著就可以在該方法內部，進行符合我們商務邏輯的異常處理 * @see 第三步：在需要拋異常的地方拋出來就行了，第二步所建立的方法會自動截獲並處理的 * @author http://blog.csdn/net/jadyer * @create May 12, 2012 7:28:31 PM */@Controller@RequestMapping("/user")@SessionAttributes("loginUser")public class UserController {private final static Map<String,User> users = new HashMap<String,User>();//類比資料源,構造初始資料public UserController(){users.put("張起靈", new User("張起靈", "悶油瓶", "02200059", "menyouping@yeah.net"));users.put("李尋歡", new User("李尋歡", "李探花", "08866659", "lixunhuan@gulong.cn"));users.put("拓拔野", new User("拓拔野", "搜神記", "05577759", "tuobaye@manhuang.cc"));users.put("孫悟空", new User("孫悟空", "美猴王", "03311159", "sunhouzi@xiyouji.zh"));}/** * 用於異常處理的方法 */@ExceptionHandler(UserException.class)public String myExceptionHandler(Exception ex, HttpServletRequest request){request.setAttribute("myex", ex);return "error";}/** * 使用者登入 * @see SpringMVC會自動收集表單控制項值，賦給方法的同名參數上 */@RequestMapping(value="/login", method=RequestMethod.POST)public String login(String username, String password, Model model){if(!users.containsKey(username)){throw new UserException("使用者不存在");}if(!users.get(username).getPassword().equals(password)){throw new UserException("密碼不正確");}model.addAttribute("loginUser", users.get(username)); //將登入使用者資訊放到HttpSession中return "user/loginSuccess";}}