1、概述
SpringMVC中Interceptor的主要作用是拦截用户请求并进行相应的的处理。可以用拦截器进行用户权限验证，或者判定用户是否已经登陆。
拦截器的配置时可插拔式的设计。对于需要使用的拦截器，只需要在配置文件中进行配置。
2、HandlerInterceptor接口
自定义Interceptor拦截器类需要实现HandlerInterceptor接口或者继承抽象类HandlerInterceptorAdapter。
HandlerInterceptor拦截器接口中有三个方法。SpringMVC通过这三个方法来对用户请求进行拦截处理。
三个方法的使用参考AuthorizationInterceprot代码注释
3、拦截器权限验证
登录页面
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <!DOCTYPE html> 4 <html> 5 <head> 6 <meta charset="UTF-8"> 7 <title>登录页面</title> 8 </head> 9 <body> 10 <form action="login" method="post"> 11 <!-- 提示信息 --> 12 <font color="red">${message }</font> 13 <table> 14 <tr> 15 <td>用户名：</td> 16 <td><input type="text" name="username" id="username"></td> 17 </tr> 18 <tr> 19 <td>密码：</td> 20 <td><input type="password" name="password" id="password"></td> 21 </tr> 22 <tr> 23 <td><input type="submit" value="登录"></td> 24 </tr> 25 </table> 26 </form> 27 </body> 28 </html>
UserController
1 package com.alphajuns.controller; 2 3 import javax.servlet.http.HttpSession; 4 5 import org.springframework.stereotype.Controller; 6 import org.springframework.ui.Model; 7 import org.springframework.web.bind.annotation.RequestMapping; 8 import org.springframework.web.servlet.ModelAndView; 9 10 import com.alphajuns.domain.Customer; 11 12 @Controller 13 public class UserController { 14 15 @RequestMapping(value="/login") 16 public ModelAndView login(String username, String password, 17 ModelAndView mv, HttpSession session) { 18 // 模拟登录 19 if (username != null && username.equals("Test") 20 && password != null && password.equals("123456")) { 21 // 将用户信息保存到session中 22 Customer c = new Customer(); 23 c.setUsername(username); 24 c.setPassword(password); 25 session.setAttribute("customer", c); 26 // 转发到首页 27 mv.setViewName("redirect:main"); 28 } else { 29 // 登录失败，给出提示信息，跳转到登录页面 30 mv.addObject("message", "用户名或密码错误，请重新登录！"); 31 mv.setViewName("loginForm"); 32 } 33 return mv; 34 } 35 36 }
BookController
1 package com.alphajuns.controller; 2 3 import java.util.ArrayList; 4 import java.util.List; 5 6 import org.springframework.stereotype.Controller; 7 import org.springframework.ui.Model; 8 import org.springframework.web.bind.annotation.RequestMapping; 9 10 import com.alphajuns.domain.Book; 11 12 @Controller 13 public class BookController { 14 15 @RequestMapping(value="/main") 16 public String main(Model model) { 17 List<Book> book_list = new ArrayList<Book>(); 18 book_list.add(new Book(1, "Spring实战", "Craig Walls")); 19 book_list.add(new Book(2, "疯狂Java讲义", "李刚")); 20 book_list.add(new Book(3, "并发编程实战", "Brian Goetz")); 21 book_list.add(new Book(4, "Java编程思想", "Bruce Eckel")); 22 model.addAttribute("book_list", book_list); 23 return "main"; 24 } 25 }
main.jsp
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> 4 <!DOCTYPE html> 5 <html> 6 <head> 7 <meta charset="UTF-8"> 8 <title>首页</title> 9 </head> 10 <body> 11 <h3>欢迎[${sessionScope.customer.username }]访问</h3> 12 <table border="1px" cellspacing="0" cellpadding="0"> 13 <tr> 14 <td>序号</td><td>书名</td><td>作者</td> 15 </tr> 16 <c:forEach items="${requestScope.book_list }" var="book"> 17 <tr> 18 <td>${book.id }</td> 19 <td>${book.name }</td> 20 <td>${book.author }</td> 21 </tr> 22 </c:forEach> 23 </table> 24 </body> 25 </html>
AuthorizationInterceptor
1 package com.alphajuns.interceptor; 2 3 import javax.servlet.http.HttpServletRequest; 4 import javax.servlet.http.HttpServletResponse; 5 6 import org.springframework.web.servlet.HandlerInterceptor; 7 import org.springframework.web.servlet.ModelAndView; 8 9 import com.alphajuns.domain.Customer; 10 11 public class AuthorizationIntercepor implements HandlerInterceptor { 12 13 // 定义方形路径 14 private static final String[] IGNORE_URI = {"/loginForm", "/login"}; 15 16 /** 17 * 整个请求完之后执行，主要用于资源清理 18 */ 19 @Override 20 public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) 21 throws Exception { 22 System.out.println("AuthorizationInterceptor afterCompletion -->"); 23 } 24 25 /** 26 * Controller调用完之后，视图返回之前执行 27 */ 28 @Override 29 public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, 30 ModelAndView modelAndView) throws Exception { 31 System.out.println("AuthorizationInterceptor postHandle -->"); 32 } 33 34 /** 35 * Controller调用之前执行，返回true才能继续向下执行 36 */ 37 @Override 38 public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) 39 throws Exception { 40 boolean flag = false; 41 // 获取请求的路径 42 String servletPath = request.getServletPath(); 43 // 判断请求是否需要拦截 44 for (String s : IGNORE_URI) { 45 if (servletPath.contains(s)) { 46 flag = true; 47 break; 48 } 49 } 50 // 拦截请求 51 if (!flag) { 52 // 获取session中的用户 53 Customer c = (Customer) request.getSession().getAttribute("customer"); 54 // 判断用户是否已登录 55 if (c == null) { 56 // 用户未登录，设置提示信息，跳转至登录页面 57 System.out.println("AuthorizationInceptor 拦截请求："); 58 request.setAttribute("message", "请先登录再访问网站！"); 59 request.getRequestDispatcher("WEB-INF/jsp/loginForm.jsp").forward(request, response); 60 } else { 61 System.out.println("AuthorizationInceptor 请求放行："); 62 flag = true; 63 } 64 } 65 return flag; 66 } 67 68 69 }
配置拦截器
1 <!-- 配置拦截器 --> 2 <mvc:interceptors> 3 <mvc:interceptor> 4 <!-- 拦截所有请求 --> 5 <mvc:mapping path="/*"/> 6 <!-- 拦截器 --> 7 <bean class="com.alphajuns.interceptor.AuthorizationIntercepor"></bean> 8 </mvc:interceptor> 9 </mvc:interceptors>