Java使用DFA算法实现过滤多家公司自定义敏感字功能详解

本文实例讲述了Java使用DFA算法实现过滤多家公司自定义敏感字功能。分享给大家供大家参考，具体如下：

背景

因为最近有通讯有个需求，说需要让多家客户公司可以自定义敏感词过滤掉他们自定义的规则，选择了DFA算法来做，不过和以前传统了DFA写法不太一样了

模式图

直接上代码

public class KeywordFilter {
//  private static ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
  public static Map currentMap = new ConcurrentHashMap();
  public static Map nowhash = null;
  public static Object wordMap;// map子节点
  // 不建立对象
  private KeywordFilter() {
  }
  private static String getKey(int companyId) {
    return "companyId" + companyId;
  }
  /*
   * 
说明:清扫内容
   *
   * @author:姚旭民
   *
   * @data:2017-8-22 上午10:13:11
   */
  public static void clear() {
    try {
      currentMap.clear();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
    }
  }
  /*
   * 
说明:各个渠道的过滤字符
   *
   * @author:姚旭民
   *
   * @data:2017-8-20 下午2:55:06
   */
  public static void saveKeywords(int companyId, List keywords) {
    try {
      Map tempAllMap = currentMap;
      String key = getKey(companyId);
      int l = keywords.size();
      int il;
      Map tempMap;
      for (int i = 0; i < l; i++) {
        String key2 = keywords.get(i).trim();// 去掉空白
        nowhash = currentMap;
        il = key2.length();
        for (int j = 0; j < il; j++) {
          char word = key2.charAt(j);
          tempMap = (Map) nowhash.get(word);
          wordMap = nowhash.get(word);
          if (wordMap != null) {// 检查数据
            if (!tempMap.containsKey(key)) {
              nowhash.put(key, 0);
            }
            nowhash = (HashMap) wordMap;
          } else {
            HashMap newWordHash = new HashMap();
            newWordHash.put(key, "0");
            nowhash.put(word, newWordHash);
            nowhash = newWordHash;
          }
          if (j == il - 1) {
            nowhash.put(key, "1");
          }
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      nowhash = null;
      wordMap = null;
    }
  }
  /*
   * 
说明:替换掉对应的渠道规定掉敏感字
   *
   * @author:姚旭民
   *
   * @data:2017-8-20 上午11:41:47
   */
  public static List repword(int companyId, String txt) {
    Map tempMap = currentMap;
    List result = new ArrayList();
    String key = getKey(companyId);
    nowhash = currentMap;
    int l = txt.length();
    char word;
    String keywordStr = "";
    String keyStatu;
    StringBuilder keyword = new StringBuilder();// 敏感字
    for (int i = 0; i < l; i++) {
      word = txt.charAt(i);
      wordMap = nowhash.get(word);
      if (wordMap != null) {// 找到类似敏感字的字体，开始查询
        keyword.append(word);
        Object te = nowhash = (HashMap) wordMap;
        // 遍历到这一步，就符合完整的关键字模板
        if (nowhash.get(key) != null
            && nowhash.get(key).toString().equals("1")) {// 确定是敏感字，开始替换
          if (i < l - 1 && nowhash.get(txt.charAt(i + 1)) != null) {// 优先过滤长敏感词，去掉就槟城了优先过滤段敏感词
            continue;
          }
          txt = txt.replaceAll(keyword.toString(), "*");
          nowhash = currentMap;
          keywordStr += keyword.toString() + ",";
          i = i - keyword.length() + 1;
          l = txt.length();// 重新获取字符长度
          keyword.delete(0, keyword.length());// 清空数据
        }
      } else {// 这个字不是敏感字，直接排除
        nowhash = currentMap;
        keyword.delete(0, keyword.length());// 清空数据
        continue;
      }
    }
    // 清除内存指向
    nowhash = null;
    wordMap = null;
    result.add(txt);
    result.add(keywordStr.length() - 1 > 0 ? keywordStr.substring(0,
        keywordStr.length() - 1) : keywordStr);
    return result;
  }
  /*
   * 
说明:检查是否存在敏感字
   *
   * @author:姚旭民
   *
   * @data:2017-8-20 下午3:00:06 专门设计成私有的，如果没有理由，别改动他
   */
  private static int checkKeyWords(String txt, int companyId, int begin) {
    int result = 0;
    String key = getKey(companyId);
    try {
      nowhash = currentMap;
      int l = txt.length();
      char word = 0;
      for (int i = begin; i < l; i++) {
        word = txt.charAt(i);
        wordMap = nowhash.get(word);
        if (wordMap != null) {
          result++;
          nowhash = (HashMap) wordMap;
          if (((String) nowhash.get(key)).equals("1")) {
            nowhash = null;
            wordMap = null;
            return result;
          }
        } else {
          result = 0;
          break;
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      nowhash = null;
      wordMap = null;
      return result;
    }
  }
  /*
   * 
说明:返回检查的文本中包含的敏感字
   *
   * @author:姚旭民
   *
   * @data:2017-8-20 下午3:32:53
   */
  public static String getTxtKeyWords(String txt, int companyId) {
    String result = null;
    StringBuilder temp = new StringBuilder();
    String key;
    int l = txt.length();
    for (int i = 0; i < l;) {
      int len = checkKeyWords(txt, companyId, i);
      if (len > 0) {
        key = (txt.substring(i, i + len));// 挑选出来的关键字
        temp.append(key + ",");
        txt = txt.replaceAll(key, "");// 挑选出来的关键字替换成空白，加快挑选速度
        l = txt.length();
      } else {
        i++;
      }
    }
    if (temp.length() > 0) {
      result = temp.substring(0, temp.length() - 1);
    }
    return result;
  }
  /*
   * 
说明:判断文中是否包含渠道规定的敏感字
   *
   * @author:姚旭民
   *
   * @data:2017-8-20 下午3:33:19
   */
  public boolean isKeyWords(String txt, int companyId) {
    for (int i = 0; i < txt.length(); i++) {
      int len = checkKeyWords(txt, companyId, i);
      if (len > 0) {
        return true;
      }
    }
    return false;
  }
  public static void main(String[] arg) {
    List keywords = new ArrayList();
    keywords.add("傻×");
    keywords.add("汉奸");
    keywords.add("草");
    keywords.add("草泥马");
    KeywordFilter.saveKeywords(1, keywords);
    String txt = "是傻×汉奸傻A傻B傻C傻D汉奸傻×草泥马";
    List list = repword(1, txt);
    System.out.println("文中包含的敏感字为:" + list.get(1));
    System.out.println("原文:" + txt);
    System.out.println("敏感字过滤后:" + list.get(0));
  }
}

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