java 中过滤器的应用

java中的过滤器

在web项目中的 web.xml 中这样配置
处理的类则为 com.gx.FilterTest

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<filter>
<filter-name>setpath</filter-name>
<filter-class>com.gx.FilterTest</filter-class>
</filter>
<filter-mapping>
<filter-name>setpath</filter-name>
<url-pattern>/admin</url-pattern>
</filter-mapping>

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


FilterTest 类的代码

package com.gx;
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;


public class FilterTest implements Filter {

public void destroy() {

}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
System.out.println("***********doFilter()************");
request.getRequestDispatcher("hello.jsp").forward(request, response);
//chain.doFilter(request,response);
}

public void init(FilterConfig arg0) throws ServletException {
System.out.println("***********init()************");
}

}


然后当要访问的页面中出现 /admin 路径时候 就会进行相应的过滤