简单实现敏感词过滤功能

现在基本所有的网页都存在敏感词过滤的功能，最近开发项目的时候，需要一个敏感词过滤的功能，参考了很多博客，便对此做了总结和自己的开发代码。
一、构建敏感词库
读取文件数据，并保存到HashMap中，构建一个DFA模型（字典树）

public class SensitiveWordInit {

    public static Map sensitiveWordMap = null;


    /**
     *  加载敏感词库
     * @return
     * @throws Exception
     */
    public Set<String> LoadSetitiveWord() throws Exception{
        InputStream inputStream = null;
        InputStreamReader inputStreamReader = null;
        BufferedReader bufferedReader = null;
        Set<String> set = new HashSet<String>();
        try{
            inputStream = getClass().getClassLoader().getResourceAsStream("CensorWords.txt");

            inputStreamReader = new InputStreamReader(inputStream,"UTF-8");

            bufferedReader = new BufferedReader(inputStreamReader);

            String str = null;
            while((str=bufferedReader.readLine())!=null){
                set.add(str);
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if(bufferedReader!=null){
                bufferedReader.close();
            }
            if(inputStreamReader!=null){
                inputStreamReader.close();
            }
            if(inputStream!=null){
                inputStream.close();
            }
        }
        return set;
    }

    /**
     *  把敏感词加入到HashMap
     * @param keyWordSet
     * @return
     */
    public Map addSensitiveWordToHashMap(Set<String> keyWordSet){
        sensitiveWordMap  = new HashMap(keyWordSet.size());
        Map nowMap = null;
        Iterator iterator = keyWordSet.iterator();
        while(iterator.hasNext()){
            String str = (String) iterator.next();
            nowMap = sensitiveWordMap;
            for(int i = 0;i<str.length();i++){
                char word = str.charAt(i);
                Object wordMap = sensitiveWordMap.get(word);
                if(wordMap!=null){
                    nowMap = (Map) wordMap;
                }else{
                    Map<String,String> newMap = new HashMap<String,String>();
                    newMap.put("isEnd","0");
                    nowMap.put(word,newMap);
                    nowMap = newMap;
                }
                if(i==str.length()-1){
                    nowMap.put("isEnd","1");
                }
            }
        }
        return sensitiveWordMap;
    }
}

二、敏感词的工具类
敏感词库构建好，利用java提供的replaceAll方法实现敏感词的替换。所有要实现一个获取文本中敏感词集合的方法，如下：

public class SensitiveWordUtils {
    /**
     * 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;

    /**
     *  返回从beginIndex开始的敏感词长度
     * @param txt
     * @param beginIndex
     * @param matchType
     * @return
     */
    public static int checkSensitiveWordSum(String txt, int beginIndex, int matchType) throws Exception{
        boolean flag = false;
        int sensitiveSum = 0;   //返回敏感词长度
        sensitiveWordMap = SensitiveWordInit.sensitiveWordMap;
        for(int i = beginIndex;i<txt.length();i++){
            char key = txt.charAt(i);
            sensitiveWordMap = (Map)sensitiveWordMap.get(key);
            if(sensitiveWordMap!=null){
                sensitiveSum++;
                if(sensitiveWordMap.get("isEnd").equals("1")){
                    flag = true;
                    if(matchType == minMatchType){
                        break;
                    }
                }
            }else{
                break;
            }
        }
        if(!flag || sensitiveSum<2){
            sensitiveSum = 0;
        }
        return sensitiveSum;
    }

    /**
     * 获取txt文本中的敏感词并保存
     *  为后续的replaceAll方法做准备工作
     * @param txt
     * @param matchType
     * @return
     */
    public static Set<String> getSensitiveWord(String txt,int matchType) throws  Exception{
        Set<String> sensitiveWord = new HashSet<String>();
        for (int i = 0; i < txt.length(); i++) {
            int sum = checkSensitiveWordSum(txt,i,matchType);
            if (sum > 0) {
                // 将检测出的敏感词保存到集合中
                sensitiveWord.add(txt.substring(i, i + sum));
                i = i + sum - 1;   //减一的目的是i下一次循环递增了
            }
        }
        return sensitiveWord;
    }

    /**
     * 替换敏感词
     *  无论敏感词长度多大，默认替代字符“***”
     * @param txt
     * @param matchType
     * @return
     */
    public static String replaceSensitiveWord(String txt, int matchType) throws Exception{
        String resultTxt = txt;
        Set<String> set = getSensitiveWord(txt, matchType);
        Iterator<String> iterator = set.iterator();
        String word = null;   //敏感词
        String replaceTxt = "***";   // 替换字符，这里默认“***”
        while (iterator.hasNext()) {
            word = iterator.next();
            resultTxt = resultTxt.replaceAll(word,replaceTxt);
        }
        return resultTxt;
    }
}

注意：minMatchType和maxMatchType的设立主要是解决敏感词长度为1个的时候不进行替换

来源：https://blog.csdn.net/weixin_44607960/article/details/99475610