通过过滤器实现控制动态资源不要缓存

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;
//控制动态资源不要缓存过滤器
public class NoCacheFilter implements Filter {

public void init(FilterConfig filterConfig) throws ServletException {

}

public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {

//      HttpServletRequest request = (HttpServletRequest)req;
//      HttpServletResponse response = (HttpServletResponse)resp;

HttpServletRequest request = null;
HttpServletResponse response = null;
try{
request  = (HttpServletRequest)req;
response = (HttpServletResponse)resp;
}catch(Exception e){
throw new RuntimeException("not-http request or response");
}

response.setHeader("Expires", "-1");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
chain.doFilter(request, response);
}

public void destroy() {

}

}

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletDemo3 extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

response.getWriter().write("中文你随便输");
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}

}

<?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"> 
<servlet>
<servlet-name>ServletDemo3</servlet-name>
<servlet-class>ServletDemo3</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>ServletDemo3</servlet-name>
<url-pattern>/servlet/ServletDemo3</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

<filter>
<filter-name>NoCacheFilter</filter-name>
<filter-class>com.itheima.example.NoCacheFilter</filter-class>
</filter>
<filter-mapping><!-- 按照此标签的出现顺序 -->
<filter-name>NoCacheFilter</filter-name>
<url-pattern>*.jsp</url-pattern>
</filter-mapping>

</web-app>