web.xml配置五個有用的過濾器

web.xml配置五個有用的過濾器

轉載自：http://royzhou1985.iteye.com/blog/418318

一、使瀏覽器不緩存頁面的過濾器   

Java代碼 

import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
* 用於的使 Browser 不緩存頁面的過濾器
*/
public class ForceNoCacheFilter implements Filter {
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException,ServletException  {
        ((HttpServletResponse) response).setHeader("Cache-Control","no-cache");
        ((HttpServletResponse) response).setHeader("Pragma","no-cache");
        ((HttpServletResponse) response).setDateHeader ("Expires", -1);
        filterChain.doFilter(request, response);
    }

    public void destroy() {
    }

    public void init(FilterConfig filterConfig) throws ServletException {
    }
}

  
二、檢測用戶是否登陸的過濾器   
Java代碼 

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.List;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.io.IOException;

/**
* 用於檢測用戶是否登陸的過濾器，如果未登錄，則重定向到指的登錄頁面
* 配置參數
* checkSessionKey 需檢查的在 Session 中保存的關鍵字
* redirectURL 如果用戶未登錄，則重定向到指定的頁面，URL不包括 ContextPath
* notCheckURLList 不做檢查的URL列表，以分號分開，並且 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 sessionKey = null;

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

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

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

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

  

    
三、字符編碼的過濾器   
Java代碼 

import javax.servlet.*;
import java.io.IOException;

/**
* 用於設置 HTTP 請求字符編碼的過濾器，通過過濾器參數encoding指明使用何種字符編碼,用於處理Html Form請求參數的中文問題
*/
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");
    }
}

四、資源保護過濾器   
  
  Java代碼 

package catalog.view.util;

import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.Iterator;
import java.util.Set;
import java.util.HashSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
* This Filter class handle the security of the application.
*
* It should be configured inside the web.xml.
*
* @author Derek Y. Shen
*/
public class SecurityFilter implements Filter {
    //the login page uri
    private static final String LOGIN_PAGE_URI = "login.jsf";

    //the logger object
    private Log logger = LogFactory.getLog(this.getClass());

    //a set of restricted resources
    private Set restrictedResources;

    /**
    * Initializes the Filter.
    */
    public void init(FilterConfig filterConfig) throws ServletException {
      this.restrictedResources = new HashSet();
      this.restrictedResources.add("/createProduct.jsf");
      this.restrictedResources.add("/editProduct.jsf");
      this.restrictedResources.add("/productList.jsf");
    }

    /**
    * Standard doFilter object.
    */
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
       throws IOException, ServletException {
        this.logger.debug("doFilter");

        String contextPath = ((HttpServletRequest)req).getContextPath();
        String requestUri = ((HttpServletRequest)req).getRequestURI();

        this.logger.debug("contextPath = " + contextPath);
        this.logger.debug("requestUri = " + requestUri);

        if (this.contains(requestUri, contextPath) && !this.authorize((HttpServletRequest)req)) {
            this.logger.debug("authorization failed");
            ((HttpServletRequest)req).getRequestDispatcher(LOGIN_PAGE_URI).forward(req, res);
        } else {
            this.logger.debug("authorization succeeded");
            chain.doFilter(req, res);
        }
    }

    public void destroy() {}

    private boolean contains(String value, String contextPath) {
        Iterator ite = this.restrictedResources.iterator();

        while (ite.hasNext()) {
            String restrictedResource = (String)ite.next();
            if ((contextPath + restrictedResource).equalsIgnoreCase(value)) {
                return true;
            }
        }

        return false;
    }

    private boolean authorize(HttpServletRequest req) {

        //處理用戶登錄
        UserBean user = (UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN);
        if (user != null && user.getLoggedIn()) {
            //user logged in
            return true;
        } else {
            return false;
        }
    }
}

五 利用Filter限制用戶瀏覽權限 
Java代碼 
在一個系統中通常有多個權限的用戶。不同權限用戶的可以瀏覽不同的頁面。使用Filter進行判斷不僅省下了代碼量，而且如果要更改的話只需要在Filter文件裏動下就可以。   
以下是Filter文件代碼：   
  

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;

public class RightFilter implements Filter {

    public void destroy() {
    }

    public void doFilter(ServletRequest sreq, ServletResponse sres, FilterChain arg2) throws IOException, ServletException {
        // 獲取uri地址
        HttpServletRequest request=(HttpServletRequest)sreq;
        String uri = request.getRequestURI();
        String ctx=request.getContextPath();
        uri = uri.substring(ctx.length());
        //判斷admin級別網頁的瀏覽權限
        if(uri.startsWith("/admin")) {
            if(request.getSession().getAttribute("admin")==null) {
                request.setAttribute("message","您沒有這個權限");
                request.getRequestDispatcher("/login.jsp").forward(sreq,sres);
                return;
            }
         }
        //判斷manage級別網頁的瀏覽權限
        if(uri.startsWith("/manage")) {
        }
        //下面還可以添加其他的用戶權限，省去。

     }

     public void init(FilterConfig arg0) throws ServletException {
     }

}

Xml代碼 
<!-- 判斷頁面的訪問權限 -->     
  <filter>     
     <filter-name>RightFilter</filter-name>     
      <filter-class>cn.itkui.filter.RightFilter</filter-class>     
  </filter>     
  <filter-mapping>     
      <filter-name>RightFilter</filter-name>     
      <url-pattern>/admin/*</url-pattern>     
  </filter-mapping>     
  <filter-mapping>     
      <filter-name>RightFilter</filter-name>     
      <url-pattern>/manage/*</url-pattern>     
  </filter-mapping>    

<!-- 判斷頁面的訪問權限 -->  
<filter>  
<filter-name>RightFilter</filter-name>  
<filter-class>cn.itkui.filter.RightFilter</filter-class>  
</filter>  
<filter-mapping>  
<filter-name>RightFilter</filter-name>  
<url-pattern>/admin/*</url-pattern>  
</filter-mapping>  
<filter-mapping>  
<filter-name>RightFilter</filter-name>  
<url-pattern>/manage/*</url-pattern>  
</filter-mapping>  

在web.xml中加入Filter的配置，如下： 
Xml代碼 
<filter>     
<filter-name>EncodingAndCacheflush</filter-name>     
<filter-class>EncodingAndCacheflush</filter-class>     
<init-param>     
<param-name>encoding</param-name>     
<param-value>UTF-8</param-value>     
</init-param>     
    </filter>     
    <filter-mapping>     
        <filter-name>EncodingAndCacheflush</filter-name>     
        <url-pattern>/*</url-pattern>     
    </filter-mapping>    
<filter>  
<filter-name>EncodingAndCacheflush</filter-name>  
<filter-class>EncodingAndCacheflush</filter-class>  
<init-param>  
<param-name>encoding</param-name>  
<param-value>UTF-8</param-value>  
</init-param>  
</filter>  
<filter-mapping>  
<filter-name>EncodingAndCacheflush</filter-name>  
<url-pattern>/*</url-pattern>  
</filter-mapping>  

要傳遞參數的時候最好使用form進行傳參，如果使用鏈接的話當中文字符的時候過濾器轉碼是不會起作用的，還有就是頁面上 

form的method也要設置爲post，不然過濾器也起不了作用。