过滤器的应用.txt

这是一个JAVA的过滤器的应用的例子

/** 
* @(#) UserAuthenticateFilter.java 
* 
* Copyright 2004 Opensource Develop Team. All rights reserved. 
*/ 

// package 
package com.opensource.filter; 

// imports 
import sun.misc.BASE64Decoder; 

import javax.servlet.*; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import javax.servlet.http.HttpSession; 
import java.io.IOException; 
import java.sql.Connection; 
import java.sql.PreparedStatement; 
import java.sql.ResultSet; 
import java.sql.SQLException; 

import com.opensource.database.ConnectFactory; 

/** 
* 进行用户身份验证，通过和数据库相连取得用户信息。 
* 
* @author: ODT 
* @see: Filter 
* @version: 1.0 21/04/2004 
* @since: 1.3 
*/ 
public class UserAuthenticateFilter implements Filter 
{ 
     private FilterConfig filterConfig = null; 
    private String adhocPassword = null; 

    public void doFilter(ServletRequest request, ServletResponse response, 
                         FilterChain chain) 
        throws IOException, ServletException 
    { 
        if (filterConfig == null) 
            return; 

        HttpServletRequest myReq = (HttpServletRequest) request; 
        HttpServletResponse myResp = (HttpServletResponse) response; 
        HttpSession session = myReq.getSession(); 

        String authString = myReq.getHeader("Authorization"); 

        if (authString == null) 
        { 
         // 修改realm 
            myResp.addHeader("WWW-Authenticate", "BASIC realm=\"OpenSource\""); 
            myResp.setStatus(HttpServletResponse.SC_UNAUTHORIZED); 
            return; 
        } 
        else 
        { 
            // atuhenticate 
            BASE64Decoder decoder = new BASE64Decoder(); 
            String enString = authString.substring(6); 
            String decString = new String(decoder.decodeBuffer(enString)); 
            int idx = decString.indexOf(":"); 
            String uid = decString.substring(0, idx); 
            String pwd = decString.substring(idx+1); 

            if (!externalAuthenticate(uid, pwd)) 
            { 
           // 修改realm 
           myResp.addHeader("WWW-Authenticate", "BASIC realm=\"OpenSource\""); 
                myResp.setStatus(HttpServletResponse.SC_UNAUTHORIZED); 
                return; 
            } 

            session.setAttribute("username", uid); 
            session.setAttribute("password", pwd); 
        } 

        filterConfig.getServletContext().log("in AdHocAuthenticateFilter"); 
        chain.doFilter(request, response); 
        filterConfig.getServletContext().log("Getting out of AdHocAuthenticateFilter"); 
    } 
      
    /** 
     * 数据库查询可自己修改 
     * @param: user -- 用户名 
     * @param: password -- 密码 
     * @return: boolean 
     */ 
    private boolean externalAuthenticate(String user, String password) 
    { 
         Connection myConnection = new ConnectFactory().getConnection(); 

        try 
        { 
            String confirmSql = 
                    "Select USERNAME, PASSWORD FROM USERS Where " + 
                     "USERNAME=? AND PASSWORD=?"; 
            PreparedStatement prep = myConnection.prepareStatement(confirmSql); 
            prep.setString(1, user); 
            prep.setString(2, password); 
            ResultSet rs = prep.executeQuery(); 
            if (rs.next()) 
            { 
                 myConnection.close(); 
                return true; 
            } 
        } 
        catch (SQLException sqle) 
        { 
            return false; 
        } 

         return false; 
    } 

    public void destroy(){} 

    public void init(FilterConfig filterConfig) 
    { 
        if (adhocPassword == null) 
            adhocPassword = "aaaa"; 
           this.filterConfig = filterConfig; 
    } 

    public String toString() 
    { 
        if (filterConfig == null) 
            return ("AdHocAuthenticateFilter()"); 

        StringBuffer sb = new StringBuffer("AdHocAuthenticateFilter("); 
        sb.append(filterConfig); 
        sb.append(")"); 
        return (sb.toString()); 
    } 
} 


安装配置UserAuthenticateFilter 
web.xml 


代码:
<filter> 
     <filter-name>User Authenticate</filter-name> 
     <filter-class>com.opensource.filter.UserAuthenticateFilter</filter-class> 
     <init-param> 
           <param-name>adhocPassword</param-name> 
           <!-- 可以初始化其他值 --> 
           <param-value>************</param-value>  
     </init-param> 
</filter> 

<filter-mapping> 
     <filter-name>User Authenticate</filter-name> 
     <!-- 访问/opensource/下的任何文件都需要输入密码 --> 
     <url-pattern>/opensource/*</url-pattern> 
</filter-mapping>