敏感词过滤器：利用DFA算法 进行敏感词过滤

基于java实现敏感词过滤的工具类
`package com...utils;

import com.leantech.firstminiprogramserver.core.SensitiveWordInit;

import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**

• @ClassName SensitiveFilter

• @Description 敏感词过滤器：利用DFA算法 进行敏感词过滤

• @Author xi_hua

• @Date 2022/6/1 9:48

• @Version 1.0
  */
  public class SensitiveFilter {
  //敏感词过滤器：利用DFA算法 进行敏感词过滤
  private Map sensitiveWordMap = null;

  // 最小匹配规则
  public static int minMatchType = 1;

  // 最大匹配规则
  public static int maxMatchType = 2;

  // 单例
  private static SensitiveFilter instance = null;

  // 构造函数，初始化敏感词库
  private SensitiveFilter() throws IOException {
  sensitiveWordMap = new SensitiveWordInit().initKeyWord();
  }

  // 获取单例
  public static SensitiveFilter getInstance() throws IOException {
  if (null == instance) {
  instance = new SensitiveFilter();
  }
  return instance;
  }

  // 获取文字中的敏感词
  public Set getSensitiveWord(String txt, int matchType) {
  Set sensitiveWordList = new HashSet();
  for (int i = 0; i < txt.length(); i++) {
  // 判断是否包含敏感字符
  int length = CheckSensitiveWord(txt, i, matchType);
  // 存在,加入list中
  if (length > 0) {
  sensitiveWordList.add(txt.substring(i, i + length));
  // 减1的原因，是因为for会自增
  i = i + length - 1;
  }
  }
  return sensitiveWordList;
  }
  // 替换敏感字字符
  public String replaceSensitiveWord(String txt, int matchType,
  String replaceChar) {
  String resultTxt = txt;
  // 获取所有的敏感词
  Set set = getSensitiveWord(txt, matchType);
  Iterator iterator = set.iterator();
  String word = null;
  String replaceString = null;
  while (iterator.hasNext()) {
  word = iterator.next();
  replaceString = getReplaceChars(replaceChar, word.length());
  resultTxt = resultTxt.replaceAll(word, replaceString);
  }
  return resultTxt;
  }

  /**

  • 获取替换字符串
  • @param replaceChar
  • @param length
  • @return
    */
    private 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，检查规则如下：
    

  • 如果存在，则返回敏感词字符的长度，不存在返回0

  • @param txt

  • @param beginIndex

  • @param matchType

  • @return
    */
    public int CheckSensitiveWord(String txt, int beginIndex, int matchType) {
    // 敏感词结束标识位：用于敏感词只有1位的情况
    boolean flag = false;
    // 匹配标识数默认为0
    int matchFlag = 0;
    Map nowMap = sensitiveWordMap;
    for (int i = beginIndex; i < txt.length(); i++) {
    char word = txt.charAt(i);
    // 获取指定key
    nowMap = (Map) nowMap.get(word);
    // 存在，则判断是否为最后一个
    if (nowMap != null) {
    // 找到相应key，匹配标识+1
    matchFlag++;
    // 如果为最后一个匹配规则,结束循环，返回匹配标识数
    if ("1".equals(nowMap.get("isEnd"))) {
    // 结束标志位为true
    flag = true;
    // 最小规则，直接返回,最大规则还需继续查找
    if (SensitiveFilter.minMatchType == matchType) {
    break;
    }
    }
    }
    // 不存在，直接返回
    else {
    break;
    }
    }

    if (SensitiveFilter.maxMatchType == matchType){
    if(matchFlag < 2 || !flag){ //长度必须大于等于1，为词
    matchFlag = 0;
    }
    }
    if (SensitiveFilter.minMatchType == matchType){
    if(matchFlag < 2 && !flag){ //长度必须大于等于1，为词
    matchFlag = 0;
    }
    }
    return matchFlag;
    }

}
`