通过Filter来实现留言板的敏感词过滤…
思路很简单，我们这里的敏感词是直接先放进去的，实际项目中，肯定是存在数据库中。在Filter 过滤器中，我们先拿到用户提交的留言，如果出现了敏感词，我们就用*号来替换。
代码演示:
index.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>过滤器应用示例---敏感词过滤</title> </head> <body> <h2>过滤器应用示例---敏感词过滤</h2> <form action="<c:url value='/NoteServlet'/>" method="post"> 用户名:<input type="text" name="name" /><br/><br/> <fieldset> <legend>留言板</legend> <textarea name="note" rows="10" cols="20"></textarea> </fieldset> <input type="submit" value="留言" /> </form> </body> </html>
WordsUtil.java:敏感词集合:
package cn.hncu.pubs; import java.util.ArrayList; import java.util.List; public class WordsUtil { private static List<String> list = new ArrayList<String>(); static{ //这里应该从数据库中导入敏感词的，我在这里就直接用词来模拟了 list.add("骂人"); list.add("sb"); } public static List<String> getWords(){ return list; } public static void reBuild(){ //把list中的内容存储到数据库---每一段时间存储一次 } }
NoteServlet.java
package cn.hncu.servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class NoteServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); out.println("不支持GET方式留言"); out.close(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">"); out.println("<HTML>"); out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>"); out.println(" <BODY>"); String name = request.getParameter("name"); if(name==null || name.trim().length()<=0){ out.println("名字不能为空!!!"); }else{ String words = request.getParameter("note"); out.println("<br/>"+name+"的留言是:<br/>"+ words); } out.println(" </BODY>"); out.println("</HTML>"); out.flush(); out.close(); } }
WordFilter.java:敏感词过滤
package cn.hncu.filter; import java.io.IOException; 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.HttpServletRequestWrapper; import cn.hncu.pubs.WordsUtil; public class WordFilter implements Filter{ @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { request.setCharacterEncoding("utf-8"); //在过滤器中用装饰模式把 原装request的功能增强了 //---拦截后台调用的getParamter()方法 MyRequest req = new MyRequest((HttpServletRequest)request); chain.doFilter(req, response);//放行 } @Override public void destroy() { } } class MyRequest extends HttpServletRequestWrapper{ public MyRequest(HttpServletRequest request) { super(request); } @Override public String getParameter(String name) { String str = super.getParameter(name); List<String> list = WordsUtil.getWords(); for(String word : list){ str = str.replaceAll(word, "*"); } return str; } }
配置web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" 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_3_0.xsd"> <display-name></display-name> <filter> <filter-name>wordFilter</filter-name> <filter-class>cn.hncu.filter.WordFilter</filter-class> </filter> <filter-mapping> <filter-name>wordFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <servlet> <servlet-name>NoteServlet</servlet-name> <servlet-class>cn.hncu.servlet.NoteServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>NoteServlet</servlet-name> <url-pattern>/NoteServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
演示结果:
过滤后的效果:
完整项目链接:
https://github.com/chenhaoxiang/Java/tree/master/myWordsFilterWeb
myWordsFilterWeb.zip
