[code] java过滤器三个-优快云博客

本文介绍了三种网站过滤器的应用：设置HTTP请求字符编码、添加Web设置及验证用户登录状态。详细展示了过滤器的配置参数及其在web.xml文件中的设置方式。

1.登陆过滤器
同理是网站开关过滤器
数据库一字段控制网站开关,后台可更改,无开就跳到指定的页面.
2.在每个页面的request中加入Attribute
3.中文过滤器


package com.zhao.util;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

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;
import javax.servlet.http.HttpSession;

/**   
* 用于检测用户是否登陆的过滤器，如果未登录，则重定向到指的登录页面    


* 配置参数    


* checkSessionKey 需检查的在 Session 中保存的关键字   

* redirectURL 如果用户未登录，则重定向到指定的页面，URL不包括 ContextPath   

* notCheckURLList 不做检查的URL列表，以分号分开，并且 URL 中不包括 ContextPath   

*/ 

public class CheckLoginFilter implements Filter {

	 protected FilterConfig filterConfig = null;    
     private String redirectURL = null;    
     private List notCheckURLList = new ArrayList();    
     private String checkSessionKey = null; 

	public void destroy() {
		 notCheckURLList.clear();   
	}

	public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
			FilterChain filterChain) throws IOException, ServletException {

		   HttpServletRequest request = (HttpServletRequest) servletRequest;    
		   HttpServletResponse response = (HttpServletResponse) servletResponse;    

		    HttpSession session = request.getSession();    
		   if(checkSessionKey == null)    
		   {    
		    filterChain.doFilter(request, response);    
		    return;    
		   }    
		   if((!checkRequestURIIntNotFilterList(request)) && session.getAttribute(checkSessionKey) == null)    
		   {    
		    response.sendRedirect(request.getContextPath() + redirectURL);    
		    return;    
		   }    
		   filterChain.doFilter(servletRequest, servletResponse);    


	}

	public void init(FilterConfig filterConfig) throws ServletException {

		   this.filterConfig = filterConfig;    
		   redirectURL = filterConfig.getInitParameter("redirectURL");    
		   checkSessionKey = filterConfig.getInitParameter("checkSessionKey");    

		   String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList");    

		   if(notCheckURLListStr != null)    
		   {    
		    StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");    
		    notCheckURLList.clear();    
		    while(st.hasMoreTokens())    
		    {    
		     notCheckURLList.add(st.nextToken());    
		    }    
		   }    


	}

	private boolean checkRequestURIIntNotFilterList(HttpServletRequest request)    
	{    
	   String uri = request.getServletPath() + (request.getPathInfo() == null ? "" : request.getPathInfo());    
	   return notCheckURLList.contains(uri);    
	}   

}


package com.zhao.util;

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 com.mobile.dao.jdbc.WebSetDaoJdbc;
import com.mobile.object.WebSet;

public class AddWebSetFilter implements Filter {

	private WebSetDaoJdbc wsDao;
	public void destroy() {
		// TODO Auto-generated method stub

	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {

		HttpServletRequest httpreq = (HttpServletRequest) request;
		WebSet ws = wsDao.getSet();
		httpreq.setAttribute("webset", ws);

		chain.doFilter(request, response);


	}

	public void init(FilterConfig arg0) throws ServletException {
		// TODO Auto-generated method stub
		wsDao = new WebSetDaoJdbc();
	}

}


package com.zhao.util;

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;

/**   
* 用于设置 HTTP 请求字符编码的过滤器，通过过滤器参数encoding指明使用何种字符编码,用于处理Html Form请求参数的中文问题   
*/ 

public class CharacterEncodingFilter implements Filter {

	protected FilterConfig filterConfig = null;    
	protected String encoding = "";    

	public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException    
	{    
	         if(encoding != null)    
	          servletRequest.setCharacterEncoding(encoding);    
	         filterChain.doFilter(servletRequest, servletResponse);    
	}    

	public void destroy()    
	{    
	   filterConfig = null;    
	   encoding = null;    
	}    

	     public void init(FilterConfig filterConfig) throws ServletException    
	{    
	          this.filterConfig = filterConfig;    
	         this.encoding = filterConfig.getInitParameter("encoding");    

	}    


}

web.xml


<?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">

<!--过滤器配置--> 
<filter>                  
<filter-name>myFilter</filter-name> 
<filter-class>com.zhao.util.CharacterEncodingFilter</filter-class> 
<init-param> 
  <param-name>encoding</param-name> 
  <param-value>utf-8</param-value> 
</init-param> 
</filter> 

<filter>                  
<filter-name>addwebsetFilter</filter-name> 
<filter-class>com.zhao.util.AddWebSetFilter</filter-class> 
</filter>

<filter>                  
<filter-name>checkLoginFilter</filter-name> 
<filter-class>com.zhao.util.CheckLoginFilter</filter-class>
<init-param> 
  <param-name>checkSessionKey</param-name> 
  <param-value>account</param-value> 
</init-param> 
<init-param> 
  <param-name>redirectURL</param-name> 
  <param-value>/login.jsp</param-value> 
</init-param> 
<init-param> 
  <param-name>notCheckURLList</param-name> 
  <param-value>/login.jsp</param-value> 
</init-param> 
</filter> 

<filter-mapping> 
   <filter-name>addwebsetFilter</filter-name> 
   <url-pattern>/*</url-pattern> 
</filter-mapping>

<filter-mapping> 
   <filter-name>checkLoginFilter</filter-name> 
   <url-pattern>/manager/*</url-pattern> 
</filter-mapping>

<filter-mapping> 
   <filter-name>myFilter</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>GetFeesbyId</servlet-name>
    <servlet-class>com.mobile.web.servlet.GetFeesbyId</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>GetFeesbyId</servlet-name>
    <url-pattern>/servlet/GetFeesbyId</url-pattern>
  </servlet-mapping> 


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