拦截器及 Spring MVC 整合

一、实验介绍

1.1 实验内容

本节课程主要利用 Spring MVC 框架实现拦截器以及 Spring MVC 框架的整合。

1.2 实验知识点

Spring MVC 框架
拦截器

1.3 实验环境

JDK1.8
Eclipse JavaEE

二、实验步骤

2.1 拦截器实现

在项目 hrms 的目录 src/main/java 下新建包 com.shiyanlou.interceptor，并在该包下新建类 LoginInterceptor，来验证用户是否登录，代码如下：

package com.shiyanlou.interceptor;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView; public class LoginInterceptor implements HandlerInterceptor { // 不拦截 "/login" 请求 private static final String[] IGNORE_URI = { "/login" }; @Override public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3) throws Exception { } @Override public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3) throws Exception { } // 该方法将在 Controller 处理前进行调用 @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { // flag 表示是否登录 boolean flag = false; // 获取请求的 URL String url = request.getServletPath(); for (String s : IGNORE_URI) { if (url.contains(s)) { flag = true; break; } } if (!flag) { // 获取 Session 并判断是否登录 String username = (String) request.getSession().getAttribute( "username"); if (username == null) { request.setAttribute("message", "Please log in first!"); // 如果未登录，进行拦截，跳转到登录页面 request.getRequestDispatcher("/login.jsp") .forward(request, response); } else { flag = true; } } return flag; } }

2.2 spring-mvc.xml 配置文件

在目录 src/main/resources 下新建 Spring MVC 配置文件 spring-mvc.xml，添加如下代码：

<?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:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd"> <!-- 自动扫描该包，Spring MVC 会将包下用 @Controller 注解的类注册为 Spring 的 controller --> <context:component-scan base-package="com.shiyanlou.controller" /> <!-- 设置默认配置方案 --> <mvc:annotation-driven /> <!-- 静态资源访问 --> <mvc:resources location="/" mapping="/**" /> <!-- 视图解析器 --> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/" /> <property name="suffix" value=".jsp" /> </bean> <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> <property name="maxUploadSize" value="3500000" /> <property name="defaultEncoding" value="UTF-8" /> </bean> <!-- 配置拦截器 --> <mvc:interceptors> <mvc:interceptor> <mvc:mapping path="/*" /> <bean class="com.shiyanlou.interceptor.LoginInterceptor" /> </mvc:interceptor> </mvc:interceptors> </beans>

2.3 配置 web.xml

修改项目 hrms 的 src->main->webapp->WEB-INF 目录下的 web.xml 内容如下：

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>hrms</display-name> <!-- 配置 Spring 核心监听器 --> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <!-- 指定 Spring 的配置文件 --> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:spring-mybatis.xml</param-value> </context-param> <!-- 定义 Spring MVC 前端控制器 --> <servlet> <servlet-name>springMVC</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:spring-mvc.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <!-- 为 DispatcherServlet 建立映射 --> <servlet-mapping> <servlet-name>springMVC</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <listener> <listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class> </listener> <!-- 编码过滤器 --> <filter> <filter-name>encodingFilter</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> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>encodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!-- 设置首页 --> <welcome-file-list> <welcome-file>login.jsp</welcome-file> </welcome-file-list> </web-app>