jsp实现过滤器的简单例子

web.xml配置如下：

<?xml version="1.0" encoding="UTF-8"?>

<web-app 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"
  version="3.0"
  metadata-complete="true">
<servlet>
    <servlet-name>Test</servlet-name>
    <servlet-class>test.Test</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>Test</servlet-name>
    <url-pattern>/*</url-pattern>
  </servlet-mapping>

  <welcome-file-list>
  <welcome-file>index.html</welcome-file>
</welcome-file-list>
</web-app>

test.java如下：

package test; 
import java.io.IOException;  
import java.io.PrintWriter;  
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
public class Test extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
        
          response.setContentType("text/html;charset=UTF-8");
          response.setCharacterEncoding("UTF-8");
          PrintWriter out = response.getWriter();
          out.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">");
          out.println("<HTML>");
          out.println("<HEAD><TITLE>A Servlet</TITLE></HEAD>");
          out.println(" <BODY>");
          out.println("<iframe src='http://www.baidu.com' width='100%' height='100%' scrolling='auto'> ");
          out.println("</iframe> ");
          out.println(" </BODY>");
          out.println("</HTML>");
          out.flush();
          out.close();  
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
     doGet(request,response);
 }
}

实例：jsp三层架构