java实现判断一个字符串是否包含特定关键词

朱雀 2022-09-23 11:53 414阅读 0赞

现实当中可能遇到这样的问题：管理员需要配置一些关键字，如果用户发表的评论中包含这些关键字，就做一些处理。下面的这个类可以达到这个目的。

package com.syz.util;
    
    import java.util.HashMap;
    import java.util.HashSet;
    import java.util.Iterator;
    import java.util.Map;
    import java.util.Set;
    
    public class KeyWordUtil {
        private Map<String, Object> dictionaryMap;
    
        public KeyWordUtil(Set<String> wordSet) {
            this.dictionaryMap = handleToMap(wordSet);
        }
    
        public Map<String, Object> getDictionaryMap() {
            return dictionaryMap;
        }
    
        public void setDictionaryMap(Map<String, Object> dictionaryMap) {
            this.dictionaryMap = dictionaryMap;
        }
    
        @SuppressWarnings("unchecked")
        private Map<String, Object> handleToMap(Set<String> wordSet) {
            if (wordSet == null) {
                return null;
            }
            Map<String, Object> map = new HashMap<String, Object>(wordSet.size());
            Map<String, Object> curMap = null;
            Iterator<String> ite = wordSet.iterator();
            while (ite.hasNext()) {
                String word = ite.next();
                curMap = map;
                int len = word.length();
                for (int i = 0; i < len; i++) {
                    String key = String.valueOf(word.charAt(i));
                    Map<String, Object> wordMap = (Map<String, Object>) curMap
                            .get(key);
                    if (wordMap == null) {
                        wordMap = new HashMap<String, Object>();
                        wordMap.put("isEnd", "0");
                        curMap.put(key, wordMap);
                        curMap = wordMap;
                    }
                    else {
                        curMap = wordMap;
                    }
                    if (i == len - 1) {
                        curMap.put("isEnd", "1");
                    }
                }
            }
            return map;
        }
    
        @SuppressWarnings("unchecked")
        public int checkWord(String text, int beginIndex) {
            if (dictionaryMap == null) {
                throw new RuntimeException("字典不能为空！");
            }
            boolean isEnd = false;
            int wordLength = 0;
            Map<String, Object> curMap = dictionaryMap;
            int len = text.length();
            for (int i = beginIndex; i < len; i++) {
                String key = String.valueOf(text.charAt(i));
                curMap = (Map<String, Object>) curMap.get(key);
                if (curMap == null) {
                    break;
                }
                else {
                    wordLength++;
                    if ("1".equals(curMap.get("isEnd"))) {
                        isEnd = true;
                    }
                }
            }
            if (!isEnd) {
                wordLength = 0;
            }
            return wordLength;
        }
    
        public Set<String> getWords(String text) {
            Set<String> wordSet = new HashSet<String>();
            int len = text.length();
            for (int i = 0; i < len; i++) {
                int wordLength = checkWord(text, i);
                if (wordLength > 0) {
                    String word = text.substring(i, i + wordLength);
                    wordSet.add(word);
                    i = i + wordLength - 1;
                }
            }
            return wordSet;
        }
    
        public static void main(String[] args) {
            Set<String> wordSet = new HashSet<String>();
            wordSet.add("叶良辰");
            wordSet.add("叶良辰的");
            wordSet.add("叶良辰的人");
            wordSet.add("叶良辰的兄弟");
            wordSet.add("良辰");
            wordSet.add("良辰不");
            wordSet.add("呵呵");
            KeyWordUtil keyWordUtil = new KeyWordUtil(wordSet);
            Map<String, Object> map = keyWordUtil.getDictionaryMap();
            System.out.println(map);
            String text = "不错，我就是叶良辰。你的行为实在欺人太甚，你若是感觉有实力跟我玩，良辰不介意奉陪到底。呵呵，我会让你明白，良辰从不说空话。";
            int beginIndex = 6;
            int wordLength = keyWordUtil.checkWord(text, beginIndex);
            System.out.println(wordLength);
            System.out.println(keyWordUtil.getWords(text));
        }
    
    }

测试结果：

{叶={isEnd=0, 良={isEnd=0, 辰={isEnd=1, 的={isEnd=1, 兄={isEnd=0, 弟={isEnd=1}}, 人={isEnd=1}}}}}, 良={isEnd=0, 辰={isEnd=1, 不={isEnd=1}}}, 呵={isEnd=0, 呵={isEnd=1}}}
    3
    [叶良辰, 良辰, 呵呵, 良辰不]

当然还可以在此基础上加一些其它功能，如某个关键字出现多少次啊，替换关键字为星号符啊。

这个工具类的核心是创建一个字典HashMap，然后利用这个字典进行判断处理。如果此字典很大，建议在初始化此工具类时，就把它放入缓存中，以后就直接从缓存中取出，然后调用它的方法就行。