基于DFA算法的敏感词过滤--Java实现

package com.yl.common.utils;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.springframework.stereotype.Component;

/**
 * 敏感字符过滤
 * 
 * @author huangzp
 * @date 2015-6-2
 */
@Component
public class SensitiveWordUtil {

	// 以DFA算法模型存储敏感词库
	private static Map<String, Map<String, String>> sensitiveWordMap = null;

	private static final int MIN_MATCH_TYPE = 1; // 最小匹配规则
	private static final int MAX_MATCH_TYPE = 2; // 最大匹配规则

	// 当前使用的匹配规则
	private static final int CURRENT_MATCH_TYPE = Integer.valueOf(SpringContextListener.getContextProValue("sensitive.word.match.type", "1"));

	// 词组结尾标识 1-是，0-否
	private static final String ISEND_TRUE = "1";
	private static final String ISEND_FALSE = "0";

	static {
		try {
			// 将敏感词库加载为DFA模型
			addSensitiveWordToDFAModel();
			LogUtil.log.info("###### 敏感词库加载完毕 #########");
		} catch (Exception e) {
			LogUtil.log.error(e.getMessage(), e);
		}
	}

	/**
	 * 以DFA算法模型存储敏感词库 中 = { isEnd = 0 国 = { isEnd = 1 人 = {isEnd = 0 民 = {isEnd
	 * = 1} } 男 = { isEnd = 0 人 = { isEnd = 1 } } } } 五 = { isEnd = 0 星 = {
	 * isEnd = 0 红 = { isEnd = 0 旗 = { isEnd = 1 } } } }
	 * 
	 * @throws Exception
	 */
	private static void addSensitiveWordToDFAModel() throws Exception {

		if (null == sensitiveWordMap || sensitiveWordMap.size() == 0) {

			// 读取敏感词库
			Set<String> keyWordSet = readSensitiveWordFile();

			sensitiveWordMap = new HashMap<String, Map<String, String>>(keyWordSet.size()); // 初始化敏感词容器，减少扩容操作
			Map nowMap = null;
			Map<String, String> newWorMap = null;
			// 迭代keyWordSet
			Iterator<String> iterator = keyWordSet.iterator();
			while (iterator.hasNext()) {
				String key = iterator.next(); // 关键字
				nowMap = sensitiveWordMap;
				for (int i = 0; i < key.length(); i++) {
					char keyChar = key.charAt(i); // 转换成char型
					Object wordMap = nowMap.get(keyChar); // 获取

					if (null != wordMap) { // 如果存在该key，直接赋值
						nowMap = (Map) wordMap;
					} else { // 不存在则，则构建一个map，同时将isEnd设置为0，因为他不是最后一个
						newWorMap = new HashMap<String, String>();
						newWorMap.put("isEnd", ISEND_FALSE); // 不是最后一个
						nowMap.put(keyChar, newWorMap);
						nowMap = newWorMap;
					}

					if (i == key.length() - 1) {
						nowMap.put("isEnd", ISEND_TRUE); // 最后一个
					}
				}

			}
		}
	}

	/**
	 * 读取敏感词库文件中的内容
	 * 
	 * @throws Exception
	 */
	private static Set<String> readSensitiveWordFile() throws Exception {

		Set<String> set = null;

		if (null == sensitiveWordMap || sensitiveWordMap.size() == 0) {
			InputStream is = SensitiveWordUtil.class.getClassLoader().getResourceAsStream("sensitive_words.txt");
			if (null != is && is.available() > 0) {

				BufferedReader br = null;
				try {
					br = new BufferedReader(new InputStreamReader(is, StrUtil.UTF8));
					set = new HashSet<String>();
					String txt = null;
					while (null != (txt = br.readLine())) { // 读取文件，将文件内容放入到set中
						set.add(txt);
					}
				} catch (Exception e) {
					throw e;
				} finally {
					if (null != br) {
						br.close(); // 关闭文件流
					}
				}

			} else {
				LogUtil.log.error("敏感词库文件不存在");
			}

		}
		return set;
	}

	/**
	 * 判断文字是否包含敏感字符
	 */
	public static boolean isContaintSensitiveWord(String txt) {
		boolean flag = false;
		for (int i = 0; i < txt.length(); i++) {
			int matchFlag = checkSensitiveWord(txt, i); // 判断是否包含敏感字符
			if (matchFlag > 0) { // 大于0存在，返回true
				flag = true;
			}
		}
		return flag;
	}

	/**
	 * 获取文字中的敏感词
	 * 
	 * @param txt
	 * @param matchType
	 * @return
	 */
	public static Set<String> getSensitiveWord(String txt) {
		Set<String> sensitiveWordList = new HashSet<String>();

		for (int i = 0; i < txt.length(); i++) {
			int length = checkSensitiveWord(txt, i); // 判断是否包含敏感字符
			if (length > 0) { // 存在,加入list中
				sensitiveWordList.add(txt.substring(i, i + length));
				i = i + length - 1; // 减1的原因，是因为for会自增
			}
		}

		return sensitiveWordList;
	}

	/**
	 * 替换敏感字字符，默认为 "*"
	 */
	public static String replaceSensitiveWord(String txt) {
		return replaceSensitiveWord(txt, "*");
	}

	/**
	 * 替换敏感字字符
	 */
	public static String replaceSensitiveWord(String txt, String replaceChar) {
		String resultTxt = txt;
		Set<String> set = getSensitiveWord(txt); // 获取所有的敏感词
		Iterator<String> iterator = set.iterator();
		String word = null;
		String replaceString = null;
		while (iterator.hasNext()) {
			word = iterator.next();
			replaceString = getReplaceChars(replaceChar, word.length());
			resultTxt = resultTxt.replace(word, replaceString);
		}

		return resultTxt;
	}

	/**
	 * 获取替换字符串
	 */
	private static String getReplaceChars(String replaceChar, int length) {
		String resultReplace = replaceChar;
		for (int i = 1; i < length; i++) {
			resultReplace += replaceChar;
		}

		return resultReplace;
	}

	/**
	 * 检查文字中是否包含敏感字符
	 * 
	 * @return，如果存在，则返回敏感词字符的长度，不存在返回0
	 */
	public static int checkSensitiveWord(String txt, int beginIndex) {
		boolean flag = false; // 敏感词结束标识位：用于敏感词只有1位的情况
		int matchFlag = 0; // 匹配标识数默认为0
		char word = 0;
		Map nowMap = sensitiveWordMap;
		for (int i = beginIndex; i < txt.length(); i++) {
			word = txt.charAt(i);
			nowMap = (Map) nowMap.get(word); // 获取指定key
			if (null != nowMap) { // 存在，则判断是否为最后一个
				matchFlag++; // 找到相应key，匹配标识+1
				if (ISEND_TRUE.equals(nowMap.get("isEnd"))) { // 如果为最后一个匹配规则,结束循环，返回匹配标识数
					flag = true; // 结束标志位为true
					if (MIN_MATCH_TYPE == CURRENT_MATCH_TYPE) { // 最小规则，直接返回,最大规则还需继续查找
						break;
					}
				}
			} else { // 不存在，直接返回
				break;
			}
		}
		if (matchFlag < 2 || !flag) { // 长度必须大于等于1，为词
			matchFlag = 0;
		}
		return matchFlag;
	}


}