Servlet监听器过滤器

Servlet监听器，过滤器演示代码：

package com.wfc.ipfilter;

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;

public class IPFilter implements Filter {

private String allIP="";
@Override
public void destroy() {
// TODO Auto-generated method stub

}

@Override
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException {

HttpServletRequest request=(HttpServletRequest)arg0;
HttpServletResponse     response=(HttpServletResponse)arg1;
//response.setCharacterEncoding("utf-8");
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");




// TODO Auto-generated method stub
               System.out.println(allIP);
             //indexOf()的用法：没有就返回-1
               System.out.println(arg0.getRemoteAddr()+"-------------2222222----------------");

               if(allIP.indexOf(arg0.getRemoteAddr())==-1){                     
            //   arg1.getWriter().print("yyyyyyyy");

              //response.getWriter().print("我的顶我的");

               arg2.doFilter(arg0, arg1);
               //response.sendRedirect("http://baidu.com/");
               }else{
               arg1.getWriter().print("nnnnnnnnnnnnnnnnnnnnn");
               }
}

@Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub

allIP=arg0.getInitParameter("ipKey");
}

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
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_2_5.xsd">
    <filter>
        <filter-name>ip</filter-name>
        <filter-class>com.wfc.ipfilter.IPFilter</filter-class>
        <init-param>
            <param-name>ipKey</param-name>

         <!--    <param-value>192.168.30.27,127.0.0.1</param-value>    --> 
            <param-value>192.168.30.27,192.168.30.26</param-value>

        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>ip</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>A</servlet-name>
    <servlet-class>com.wfc.ipfilter.A</servlet-class>
  </servlet>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>B</servlet-name>
    <servlet-class>com.wfc.ipfilter.B</servlet-class>
  </servlet>


  <servlet-mapping>
    <servlet-name>A</servlet-name>
    <url-pattern>/A</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>B</servlet-name>
    <url-pattern>/B</url-pattern>
  </servlet-mapping>


</web-app>

对于过滤器：上面的例子就可以来完成：配置web.xml         过滤掉指定的IP地址

下面继续写了两个Servlet，上下文ServletContext的演示：

package com.wfc.ipfilter;

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 B extends HttpServlet {

/**
 * Destruction of the servlet. <br>
 * 
 */


String str="womendoasuddsfjweqtewweohe";
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}

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


}


public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();


}


public void init() throws ServletException {
// Put your code here
System.out.println("------------------------------初始化方法--------------------");


this.getServletContext().setAttribute("ggg", str);


System.out.println("B要得到值：-------------"+this.getServletContext().getAttribute("ggg"));




}

}

package com.wfc.ipfilter;

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 A extends HttpServlet {


public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}


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

this.doPost(request, response);

}

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

//System.out.println("我要得到值1："+this.getServletContext().getAttribute("ggg"));


response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.print("传递的值："+this.getServletContext().getAttribute("ggg"));
//System.out.println("我要得到值2："+this.getServletContext().getAttribute("ggg"));

}


public void init() throws ServletException {
// Put your code here
}

}