1。StaticResourcesNeedCacheFilter.java文件：
package com.itheima.example;
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;
//控制靜態資源的緩存時間
public class StaticResourcesNeedCacheFilter implements Filter {
private FilterConfig filterConfig;
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = null;
HttpServletResponse response = null;
try{
request = (HttpServletRequest)req;
response = (HttpServletResponse)resp;
}catch(Exception e){
throw new RuntimeException("not-http request or response");
}
long time = 0;//緩存的時間
//根據用戶請求的uri地址的後綴：/day19_00_filter/1.html
String uri = request.getRequestURI();
String exName = uri.substring(uri.lastIndexOf(".")+1);
if("html".equals(exName)){
String value = filterConfig.getInitParameter("html");//小時
time = Long.parseLong(value)*60*60*1000;
}
if("css".equals(exName)){
String value = filterConfig.getInitParameter("css");//小時
time = Long.parseLong(value)*60*60*1000;
}
if("js".equals(exName)){
String value = filterConfig.getInitParameter("js");//小時
time = Long.parseLong(value)*60*60*1000;
}
response.setDateHeader("Expires", System.currentTimeMillis()+time);
chain.doFilter(request, response);
}
public void destroy() {
}
}
2。web.xml文件：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
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_3_0.xsd">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<filter>
<filter-name>SetCharacterEncodingFilter</filter-name>
<filter-class>com.itheima.encoding.SetCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping><!-- 按照此標籤的出現順序 -->
<filter-name>SetCharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>StaticResourcesNeedCacheFilter</filter-name>
<filter-class>com.itheima.example.StaticResourcesNeedCacheFilter</filter-class>
<init-param>
<param-name>html</param-name>
<param-value>1</param-value>
</init-param>
<init-param>
<param-name>css</param-name>
<param-value>2</param-value>
</init-param>
<init-param>
<param-name>js</param-name>
<param-value>3</param-value>
</init-param>
</filter>
<filter-mapping><!-- 按照此標籤的出現順序 -->
<filter-name>StaticResourcesNeedCacheFilter</filter-name>
<url-pattern>*.html</url-pattern>
</filter-mapping>
<filter-mapping><!-- 按照此標籤的出現順序 -->
<filter-name>StaticResourcesNeedCacheFilter</filter-name>
<url-pattern>*.css</url-pattern>
</filter-mapping>
<filter-mapping><!-- 按照此標籤的出現順序 -->
<filter-name>StaticResourcesNeedCacheFilter</filter-name>
<url-pattern>*.js</url-pattern>
</filter-mapping>
</web-app>3。1.html文件：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>1.html</title>
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<link rel="stylesheet" type="text/css" href="main.css">
<script type="text/javascript" src="1.js"></script>
</head>
<body>
希希哥遇到了茜茜姐
</body>
</html>
4。1.jsp文件：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>title</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/ServletDemo2" method="post">
<input type="text" name="name"/><input type="submit" value="保存"/>
</form>
</body>
</html>
5。1.js文件：
alert("啊哈哈哈");6。main.css文件：
body{
color: blue;
7。運行：http://localhost:8080/Filter_project/1.html
8.結果：
彈出了“啊哈哈哈”的對話框，
輸出了：希希哥遇到了茜茜姐
