javaWEB总结(31):禁用游览器缓存的过滤器

来源：互联网发布：商城网站数据库表设计编辑：程序博客网时间：2024/04/28 07:07

前提

项目结构

web.xml

<?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" 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>javaWeb_31</display-name>  <welcome-file-list>    <welcome-file>a.jsp</welcome-file>  </welcome-file-list></web-app>

a.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>A.jsp</title></head><body><a href="b.jsp">TO B.jsp</a><br><br><img alt="" src="<%=request.getContextPath()%>/img/a.jpg"></body></html>

b.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>B.jsp</title></head><body><a href="a.jsp">TO A.jsp</a><br><br><img alt="" src="<%=request.getContextPath()%>/img/b.jpg"></body></html>

运行结果

当我们修改a.jsp后

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>A.jsp</title></head><body><a href="b.jsp">TO B.jsp</a><br><br><img alt="" src="<%=request.getContextPath()%>/img/b.jpg"></body></html>

图片依旧不变。

添加过滤器

项目结构

修改的页面web.xml

<?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" 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>javaWeb_31</display-name>  <welcome-file-list>    <welcome-file>a.jsp</welcome-file>  </welcome-file-list>    <filter>      <filter-name>Cache</filter-name>      <filter-class>com.dao.chu.Cache</filter-class>  </filter>    <filter-mapping>      <filter-name>Cache</filter-name>      <url-pattern>/*</url-pattern>  </filter-mapping>  </web-app>

添加的类

HttpFilter.java

package com.dao.chu;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** *  * <p> * Title: HttpFilter * </p> * <p> * Description: http请求定制Filter * </p> */public abstract class HttpFilter implements Filter {/** * 用于保存init(FilterConfig filterConfig)的FilterConfig对象 */private FilterConfig filterConfig;/** * 直接返回init(FilterConfig filterConfig)的FilterConfig对象 */public FilterConfig getFilterConfig() {return filterConfig;}/** * 不建议子类直接覆盖，将可能会导致filterConfig成员变量初始化失败 */@Overridepublic void init(FilterConfig filterConfig) throws ServletException {this.filterConfig = filterConfig;init();}/** * 供子类继承的初始化方法，可以通过getFilterConfig获取FilterConfig对象 */protected void init() {}/** * 原生的doFilter方法，在方法内部把ServletRequest和ServletResponse * 转为了HttpServletRequest和HttpServletResponse并调用了 doFilter(HttpServletRequest * httpRequest, HttpServletResponse httpResponse, FilterChain chain)方法 *  *  * 若编写Filter的过滤方法不建议直接继承该方法，而应该继承doFilter(ServletRequest request, * ServletResponse response, FilterChain chain) */@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {HttpServletRequest httpRequest = (HttpServletRequest) request;HttpServletResponse httpResponse = (HttpServletResponse) response;doFilter(httpRequest, httpResponse, chain);}/** * 抽象方法，为http请求定制，必需实现的方法 *  */public abstract void doFilter(HttpServletRequest httpRequest,HttpServletResponse httpResponse, FilterChain chain)throws IOException, ServletException;/** * 空的destroy方法 */@Overridepublic void destroy() {}}

Cache.java

package com.dao.chu;import java.io.IOException;import javax.servlet.FilterChain;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class Cache extends HttpFilter {@Overridepublic void doFilter(HttpServletRequest httpRequest,HttpServletResponse httpResponse, FilterChain chain)throws IOException, ServletException {System.out.println("cache doFilter");httpResponse.setDateHeader("Expires", -1); // for IEhttpResponse.setHeader("Cache-Control", "no-cache"); // for 火狐 或 其他。httpResponse.setHeader("Pragma", "no-cache"); // for 火狐 或 其他。chain.doFilter(httpRequest, httpResponse);}}

添加完此过滤器后即可禁用游览器缓存的过滤器。

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