具备白名单、黑名单的Filter基类扩展

 

 

之前有朋友问《servlet-mapping中url-pattern配置问题》

 

Mybeautiful  写道

比如我定义了一个mapping, 
<servlet-mapping> 
<servlet-name>html_dispatcher</servlet-name> 
<url-pattern>*.html</url-pattern> 
</servlet-mapping> 

就是说所有的.html请求都会由html_dispatcher来处理，但现在我的问题是： 
我希望某个文件夹下面的.html不用这个html_dispatcher处理，而所有其它的.html请求不变。 

因为把所有其它的.html列出来实在太多了，多到我都不知道有多少。所以不能一一列出。 

很明显是在白名单里边排除一部分黑名单需求。

 

 

大家在开发Java Web时，在使用过滤器时是比较挠头的，比如

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

 

url-pattern只能是如下三种：

1、前缀匹配   /user/*

2、后缀匹配  *.do

3、绝对匹配  /myservlet

而且如果我想过滤多个url必须

	<filter-mapping>
		<filter-name>TestFilter</filter-name>
		<url-pattern>/a</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>TestFilter</filter-name>
		<url-pattern>/b</url-pattern>
	</filter-mapping>

两个问题：

1、有的朋友可能需要过滤*.html 但要排除一部分（黑名单）；

2、有的朋友可能需要过滤多个url，如/a  /b，对于每一个url必须写一个filter-mapping比较繁琐；

因此我写了一个非常简单的具备白名单和黑名单功能的基类Filter，过滤url使用Ant Path：

package com.sishuok.web.filter;

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

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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.AntPathMatcher;
import org.springframework.util.PathMatcher;
/**
 * Ant语法
 * 请参考 http://jinnianshilongnian.iteye.com/blog/1416322
 *  
 *  配置方式
	<filter>
		<filter-name>TestFilter</filter-name>
		<filter-class>com.sishuok.web.filter.TestFilter</filter-class>
		<!-- url分隔符可以是 换行 空格 分号  逗号  白名单和黑名单都是可选-->
		<init-param>
		    <param-name>blackListURL</param-name> <!-- 配置黑名单url 表示不走过滤器的url order：1 -->
		    <param-value>
		    	/aa
		    	/bb/**
		    	/cc/*
		    </param-value>
		</init-param>
		<init-param>
		    <param-name>whiteListURL</param-name> <!-- 配置白名单url 表示走过滤器的url order：2-->
		    <param-value>
		    	/dd;/ee,/ff /list
		    </param-value>
		</init-param>
	</filter>
	<filter-mapping>
	<filter-name>TestFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
 * 
 * @author Zhang Kaitao
 *
 */
public abstract class BaseFilter implements Filter {
	
	private FilterConfig config = null;
			
	private final String[] NULL_STRING_ARRAY = new String[0];
	private final String URL_SPLIT_PATTERN = "[, ;\r\n]";//逗号  空格 分号  换行

	private final PathMatcher pathMatcher = new AntPathMatcher();

	private final Logger logger = LoggerFactory.getLogger("url.filter");

	/**
	 * 白名单
	 */
	private String[] whiteListURLs = null;

	/**
	 * 黑名单
	 */
	private String[] blackListURLs = null;

	@Override
	public final void init(FilterConfig config) throws ServletException {
		this.config = config;
		this.initConfig();
		this.init();
	}

	/**
	 * 子类覆盖
	 * 
	 * @throws ServletException
	 */
	public void init() throws ServletException {

	}

	/**
	 * 1、黑名单匹配 2、白名单匹配
	 */
	@Override
	public final void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
		throws IOException, ServletException {

		HttpServletRequest httpRequest = (HttpServletRequest) request;
		HttpServletResponse httpResponse = (HttpServletResponse) response;

		String currentURL = httpRequest.getServletPath();

		logger.debug("url filter : current url : [{}]", currentURL);

		if (isBlackURL(currentURL)) {
			chain.doFilter(request, response);
			return;
		}

		if (isWhiteURL(currentURL)) {
			doFilter(httpRequest, httpResponse, chain);
			return;
		}

		logger.debug("url filter : no url list matches : [{}]  break", currentURL);
		chain.doFilter(request, response);
		return;
	}

	private boolean isWhiteURL(String currentURL) {
		for (String whiteURL : whiteListURLs) {
			if (pathMatcher.match(whiteURL, currentURL)) {
				logger.debug("url filter : white url list matches : [{}] match [{}] continue", whiteURL, currentURL);
				return true;
			}
			logger.debug("url filter : white url list not matches : [{}] match [{}]", whiteURL, currentURL);
		}
		return false;
	}

	private boolean isBlackURL(String currentURL) {
		for (String blackURL : blackListURLs) {
			if (pathMatcher.match(blackURL, currentURL)) {
				logger.debug("url filter : black url list matches : [{}] match [{}] break", blackURL, currentURL);
				return true;
			}
			logger.debug("url filter : black url list not matches : [{}] match [{}]", blackURL, currentURL);
		}
		return false;
	}

	/**
	 * 子类覆盖
	 * 
	 * @param request
	 * @param response
	 * @param chain
	 * @throws IOException
	 * @throws ServletException
	 */
	public void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		chain.doFilter(request, response);
	}

	/**
	 * 子类覆盖
	 */
	@Override
	public void destroy() {

	}

	private void initConfig() {
		String whiteListURLStr = this.config.getInitParameter("whiteListURL");
		whiteListURLs = strToArray(whiteListURLStr);

		String blackListURLStr = this.config.getInitParameter("blackListURL");
		blackListURLs = strToArray(blackListURLStr);

	}

	private String[] strToArray(String urlStr) {
		if (urlStr == null) {
			return NULL_STRING_ARRAY;
		}
		String[] urlArray = urlStr.split(URL_SPLIT_PATTERN);

		List<String> urlList = new ArrayList<String>();

		for (String url : urlArray) {
			url = url.trim();
			if (url.length() == 0) {
				continue;
			}

			urlList.add(url);
		}

		return urlList.toArray(NULL_STRING_ARRAY);
	}

	public FilterConfig getConfig() {
		return config;
	}
}

 

具体使用如下：

package com.sishuok.web.filter;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TestFilter extends BaseFilter {
	@Override
	public void init() throws ServletException {//初始化
		FilterConfig config = getConfig();
	}
	
	
	@Override
	public void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
		throws IOException, ServletException {
                
		System.out.println("==============");
		chain.doFilter(request, response);
		
	}
	
	@Override
	public void destroy() {//销毁
	}
	
}

 

xml配置如下：

	<filter>
		<filter-name>TestFilter</filter-name>
		<filter-class>com.sishuok.web.filter.TestFilter</filter-class>
		<!-- url分隔符可以是 换行 空格 分号  逗号  白名单和黑名单都是可选-->
		<init-param>
		    <param-name>blackListURL</param-name> <!-- 配置黑名单url 表示不走过滤器的url order：1 -->
		    <param-value>
		    	/aa
		    	/bb/**
		    	/cc/*
		    </param-value>
		</init-param>
		<init-param>
		    <param-name>whiteListURL</param-name> <!-- 配置白名单url 表示走过滤器的url order：2-->
		    <param-value>
		    	/dd;/ee,/ff /list
		    </param-value>
		</init-param>
	</filter>
	<filter-mapping>
		<filter-name>TestFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>

 

因为相对来说实现很简单，具体实现就不详细介绍了。