屏蔽词功能实现

     自己上学的时候，经常会看到贴吧里面屏蔽各种用户的发帖内容，当时就想这个该如何去实现。自己当时想过用字符串去替代的方式（replaceAll）去实现，但是这种效率又非常低，也不能保证最长匹配，这就是自己当时最初的想法。最近自己做的一个项目中，需要对一些内容做屏蔽，自己又对这个问题做了一次分析，最终形成下面的代码。最近一直在赶项目，所以注释很少，原谅

 

转载请标明来源：http://xiaojimanman.iteye.com/admin/blogs/1978245

 

 /**  
 *@Description: 屏蔽词功能实现    
 */ 
package cn.yicha.novel.search.util;  

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;

import cn.yicha.novel.search.config.Config;
  
public class Forbidden {
	
	private static Forbidden forbidden = new Forbidden();
	//屏蔽词HashSet
	private HashSet<String> keyString = new HashSet<String>();
	private final static int maxLength = Character.MAX_VALUE;
	//屏蔽词长度HashSet数组
	@SuppressWarnings("unchecked")
	private HashSet<Integer>[] keyLength = new HashSet[maxLength];
	
	private Forbidden() {
		System.out.println(Config.getClassRoot() + "forbidden.txt");
		loadForbidden(Config.getClassRoot() + "forbidden.txt");
	}
	public static Forbidden getForbidden(){
		return forbidden;
	}
	
	/**
	 * @param str
	 * @return
	 * @Date: 2013-11-15  
	 * @Author: lulei  
	 * @Description: 输入的字符串通过屏蔽处理
	 */
	public String read(String str){
		if (str == null){
			return null;
		}
		StringBuffer stringBuffer = new StringBuffer();
		int start = 0;
		for (int i = 0; i < str.length();){
			int at = str.charAt(i);
			if (keyLength[at] == null){
				i++;
				continue;
			} else {
				int ml = 0;
				for (Object obj : keyLength[at].toArray()){
					int len = ((Integer)obj).intValue();
					if (i + len <= str.length()){
						String s = str.substring(i, i + len);
						if (keyString.contains(s)){
							ml = len > ml ? len : ml;
						}
					} 
				}
				if (ml > 0){
					stringBuffer.append(str.substring(start, i)).append("***");
					i += ml;
					start = i;
				} else {
					i++;
				}
			}
		}
		if (start < str.length()){
			stringBuffer.append(str.substring(start));
		}
		return stringBuffer.toString();
	}
	
	/**
	 * @param path
	 * @Date: 2013-11-15  
	 * @Author: lulei  
	 * @Description: 初始化加载屏蔽词
	 */
	public void loadForbidden(String path){
		File forbiddenFile = new File(path);
		FileInputStream fileInputStream;
		try {
			fileInputStream = new FileInputStream(forbiddenFile);
			InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, "utf-8");
			BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
			String s;
			while ((s = bufferedReader.readLine()) != null){
				s = s.trim();
				if (s.length() > 0){
					keyString.add(s);
					int i = s.charAt(0);
					if (keyLength[i] == null){
						HashSet<Integer> a = new HashSet<Integer>();
						a.add(s.length());
						keyLength[i] = a;
					} else {
						keyLength[i].add(s.length());
					}
				}
			}
			fileInputStream.close();
			bufferedReader.close();
			fileInputStream.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} 
	}

	public static void main(String[] args) {
		System.out.println(Forbidden.getForbidden().read("屏蔽词nihao"));
	}

}