java利用DFA算法实现敏感词过滤功能

package com.cfwx.rox.web.sysmgr.util;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.cfwx.rox.web.common.model.entity.SensitiveWord;

/**
 * 敏感词库初始化
 * 
 * @author AlanLee
 *
 */
public class SensitiveWordInit
{
  /**
   * 敏感词库
   */
  public HashMap sensitiveWordMap;

  /**
   * 初始化敏感词
   * 
   * @return
   */
  public Map initKeyWord(List<SensitiveWord> sensitiveWords)
  {
    try
    {
      // 从敏感词集合对象中取出敏感词并封装到Set集合中
      Set<String> keyWordSet = new HashSet<String>();
      for (SensitiveWord s : sensitiveWords)
      {
        keyWordSet.add(s.getContent().trim());
      }
      // 将敏感词库加入到HashMap中
      addSensitiveWordToHashMap(keyWordSet);
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
    return sensitiveWordMap;
  }

  /**
   * 封装敏感词库
   * 
   * @param keyWordSet
   */
  @SuppressWarnings("rawtypes")
  private void addSensitiveWordToHashMap(Set<String> keyWordSet)
  {
    // 初始化HashMap对象并控制容器的大小
    sensitiveWordMap = new HashMap(keyWordSet.size());
    // 敏感词
    String key = null;
    // 用来按照相应的格式保存敏感词库数据
    Map nowMap = null;
    // 用来辅助构建敏感词库
    Map<String, String> newWorMap = null;
    // 使用一个迭代器来循环敏感词集合
    Iterator<String> iterator = keyWordSet.iterator();
    while (iterator.hasNext())
    {
      key = iterator.next();
      // 等于敏感词库，HashMap对象在内存中占用的是同一个地址，所以此nowMap对象的变化，sensitiveWordMap对象也会跟着改变
      nowMap = sensitiveWordMap;
      for (int i = 0; i < key.length(); i++)
      {
        // 截取敏感词当中的字，在敏感词库中字为HashMap对象的Key键值
        char keyChar = key.charAt(i);

        // 判断这个字是否存在于敏感词库中
        Object wordMap = nowMap.get(keyChar);
        if (wordMap != null)
        {
          nowMap = (Map) wordMap;
        }
        else
        {
          newWorMap = new HashMap<String, String>();
          newWorMap.put("isEnd", "0");
          nowMap.put(keyChar, newWorMap);
          nowMap = newWorMap;
        }

        // 如果该字是当前敏感词的最后一个字，则标识为结尾字
        if (i == key.length() - 1)
        {
          nowMap.put("isEnd", "1");
        }
        System.out.println("封装敏感词库过程："+sensitiveWordMap);
      }
      System.out.println("查看敏感词库数据:" + sensitiveWordMap);
    }
  }
}

package com.cfwx.rox.web.sysmgr.util;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
 * 敏感词过滤工具类
 * 
 * @author AlanLee
 *
 */
public class SensitivewordEngine
{
  /**
   * 敏感词库
   */
  public static Map sensitiveWordMap = null;

  /**
   * 只过滤最小敏感词
   */
  public static int minMatchTYpe = 1;

  /**
   * 过滤所有敏感词
   */
  public static int maxMatchType = 2;

  /**
   * 敏感词库敏感词数量
   * 
   * @return
   */
  public static int getWordSize()
  {
    if (SensitivewordEngine.sensitiveWordMap == null)
    {
      return 0;
    }
    return SensitivewordEngine.sensitiveWordMap.size();
  }

  /**
   * 是否包含敏感词
   * 
   * @param txt
   * @param matchType
   * @return
   */
  public static boolean isContaintSensitiveWord(String txt, int matchType)
  {
    boolean flag = false;
    for (int i = 0; i < txt.length(); i++)
    {
      int matchFlag = checkSensitiveWord(txt, i, matchType);
      if (matchFlag > 0)
      {
        flag = true;
      }
    }
    return flag;
  }

  /**
   * 获取敏感词内容
   * 
   * @param txt
   * @param matchType
   * @return 敏感词内容
   */
  public static Set<String> getSensitiveWord(String txt, int matchType)
  {
    Set<String> sensitiveWordList = new HashSet<String>();

    for (int i = 0; i < txt.length(); i++)
    {
      int length = checkSensitiveWord(txt, i, matchType);
      if (length > 0)
      {
        // 将检测出的敏感词保存到集合中
        sensitiveWordList.add(txt.substring(i, i + length));
        i = i + length - 1;
      }
    }

    return sensitiveWordList;
  }

  /**
   * 替换敏感词
   * 
   * @param txt
   * @param matchType
   * @param replaceChar
   * @return
   */
  public static String replaceSensitiveWord(String txt, int matchType, String replaceChar)
  {
    String resultTxt = txt;
    Set<String> set = getSensitiveWord(txt, matchType);
    Iterator<String> 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;
  }

  /**
   * 替换敏感词内容
   * 
   * @param replaceChar
   * @param length
   * @return
   */
  private static String getReplaceChars(String replaceChar, int length)
  {
    String resultReplace = replaceChar;
    for (int i = 1; i < length; i++)
    {
      resultReplace += replaceChar;
    }

    return resultReplace;
  }

  /**
   * 检查敏感词数量
   * 
   * @param txt
   * @param beginIndex
   * @param matchType
   * @return
   */
  public static int checkSensitiveWord(String txt, int beginIndex, int matchType)
  {
    boolean flag = false;
    // 记录敏感词数量
    int matchFlag = 0;
    char word = 0;
    Map nowMap = SensitivewordEngine.sensitiveWordMap;
    for (int i = beginIndex; i < txt.length(); i++)
    {
      word = txt.charAt(i);
      // 判断该字是否存在于敏感词库中
      nowMap = (Map) nowMap.get(word);
      if (nowMap != null)
      {
        matchFlag++;
        // 判断是否是敏感词的结尾字，如果是结尾字则判断是否继续检测
        if ("1".equals(nowMap.get("isEnd")))
        {
          flag = true;
          // 判断过滤类型，如果是小过滤则跳出循环，否则继续循环
          if (SensitivewordEngine.minMatchTYpe == matchType)
          {
            break;
          }
        }
      }
      else
      {
        break;
      }
    }
    if (!flag)
    {
      matchFlag = 0;
    }
    return matchFlag;
  }

}

@SuppressWarnings("rawtypes")
  @Override
  public Set<String> sensitiveWordFiltering(String text)
  {
    // 初始化敏感词库对象
    SensitiveWordInit sensitiveWordInit = new SensitiveWordInit();
    // 从数据库中获取敏感词对象集合（调用的方法来自Dao层，此方法是service层的实现类）
    List<SensitiveWord> sensitiveWords = sensitiveWordDao.getSensitiveWordListAll();
    // 构建敏感词库
    Map sensitiveWordMap = sensitiveWordInit.initKeyWord(sensitiveWords);
    // 传入SensitivewordEngine类中的敏感词库
    SensitivewordEngine.sensitiveWordMap = sensitiveWordMap;
    // 得到敏感词有哪些，传入2表示获取所有敏感词
    Set<String> set = SensitivewordEngine.getSensitiveWord(text, 2);
    return set;
  }

/**
   * 敏感词过滤
   * 
   * @param text
   * @return
   */
  @RequestMapping(value = "/word/filter")
  @ResponseBody
  public RespVo sensitiveWordFiltering(String text)
  {
    RespVo respVo = new RespVo();
    try
    {
      Set<String> set = sensitiveWordService.sensitiveWordFiltering(text);
      respVo.setResult(set);
    }
    catch (Exception e)
    {
      throw new RoxException("过滤敏感词出错，请联系维护人员");
    }

    return respVo;
  }