过滤器-过滤敏感词汇

首先要准备好敏感词库，敏感词汇的格式如下：

短信猫|1

买枪|2

四大舰队|3

   其中1代表禁用词：禁用词将禁止提交，2代表审核次：将以高亮字体显示，3代表过滤词：将替换为****，

过滤器代码实现如下：

package cn.itcast.web.filter;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

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 javax.servlet.http.HttpServletResponse;

public class WordsFilter implements Filter {

	private List banWords = new ArrayList();  //禁用词
	private List auditWords = new ArrayList();  //审核词
	private List replaceWords = new ArrayList();  //替换词
	
	//初始化将敏感词库全部加载到集合中
	public void init(FilterConfig filterConfig) throws ServletException {
		
		try{
			String path = WordsFilter.class.getClassLoader().getResource("").getPath();  //得到类目录
			File files[] = new File(path).listFiles();			//得到目录下的所有文件
			for(File file : files){   
				//如果不是文件返回
				if(!file.isFile()){
					continue;
				}
				//如果不是txt文件返回
				if(!file.getName().endsWith(".txt")){
					continue;
				}
				//读txt文件
				BufferedReader br = new BufferedReader(new FileReader(file));
				String line = null;	
				while((line=br.readLine())!=null){
					String s[] = line.split("\\|");
					if(s.length!=2){
						continue;
					}
					String level = s[1].trim();	
					if("1".equals(level)){
						banWords.add(s[0]);
					}
					if("2".equals(level)){
						auditWords.add(s[0]);
					}
					if("3".equals(level)){
						replaceWords.add(s[0]);
					}
				}
			}

		}catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) resp;
		
		//用户提交的数据是否包含禁用词
		Enumeration e = request.getParameterNames();
		while(e.hasMoreElements()){
			String value = request.getParameter((String)e.nextElement());
			for(String regex : banWords){
				//正则表达式判断用户输入的内如是否存在
				Pattern p = Pattern.compile(regex);  
				Matcher m = p.matcher(value);
				if(m.find()){
					request.setAttribute("message", "你发表的文章中含有非法词汇，你懂的！！");
					request.getRequestDispatcher("/message.jsp").forward(request, response);
					return;
				}
			}
		}
		
		//用户提交的数据是否包含审核词和替换词，自定义包装类
		Myrequest myrequest = new Myrequest(request);
		//放行
		chain.doFilter(myrequest, response); 
	}
	
	class Myrequest extends HttpServletRequestWrapper{
		
		private HttpServletRequest request;
		public Myrequest(HttpServletRequest request){
			super(request);
			this.request = request;
		}
		@Override
		public String getParameter(String name) {
			
			String value = this.request.getParameter(name);
			if(value==null){
				return null;
			}
			
			//检查数据中是否包含审核词
			for(String regex : auditWords){
				Pattern p = Pattern.compile(regex);
				Matcher m = p.matcher(value);
				while(m.find()){
					String word = m.group();  //得到找到的那个词
					value = value.replaceAll(regex, "" + word + "");
				}
			}
			
			//检查数据中是否包含替换词
			for(String regex : replaceWords){
				Pattern p = Pattern.compile(regex);
				Matcher m = p.matcher(value);
				while(m.find()){
					value = value.replaceAll(regex, "****");
				}
			}
			return value;
		}
	}
	public void destroy() {
		// TODO Auto-generated method stub
	}
}