具备白名单、黑名单的Filter基类扩展

来源：互联网发布：arduino摄像头编程编辑：程序博客网时间：2024/05/29 09:38

问题引入：

比如定义了一个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，可以使用在白名单里排除一部分黑名单来实现。

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;/** *   *  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>

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