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JavaWeb-过滤器Filter学习(四)敏感词过滤实例

2016-08-18 17:29 716 查看
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

转载请附上原文博客链接：

http://blog.csdn.net/qq_26525215
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