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
}

}