该博客介绍了如何使用JAVA构建DFA（确定有限状态自动机）算法。首先，通过`addWordToHashMap`方法创建敏感字Map，然后利用`formatString`方法进行正则特殊符号过滤，最后通过`checkWork`方法校验字符串中是否存在敏感词。整个过程详细阐述了DFA在Java中的实现方式。
1、创建敏感字Map
public static Map addWordToHashMap(Set keyWordSet) {
if(0 == keyWordSet.size()) return new HashMap();
Map map = new HashMap(keyWordSet.size());
String key = null;
Map nowMap = null;
Map newWorMap = null;
Iterator iterator = keyWordSet.iterator();
while(iterator.hasNext()){
key = iterator.next();
nowMap = map;
for(int i = 0; i < key.length(); i++){
char keyChar = key.charAt(i);
Map wordMap = (Map) nowMap.get(keyChar);
if(wordMap != null) nowMap = wordMap;
else{
newWorMap = new HashMap();
nowMap.put(keyChar, newWorMap);
nowMap = newWorMap;
}
if(i == key.length() - 1) nowMap.put("isEnd", "1");
}
}
return map;
}
2、创建正则特殊符号过滤
public static String formatString(String str) {
if (StringUtils.isNotBlank(str)) {
String regEx="[`~!@#$%^&*()+=|{}':;',\\[\\].<>/?~！@#￥%……&*()——+|{}【】‘；：”“’。，、？]";
return Pattern.compile(regEx).matcher(str).replaceAll("").trim();
}
return "";
}
3、校验字符串
public static String checkWork(String txt, Map map, boolean needToFormat) {
try {
if (needToFormat) txt = formatString(txt);
StringBuffer sb = new StringBuffer();
boolean has = false;
char word;
int num;
for (int i = 0; i < txt.length(); i++) {
word = txt.charAt(i);
sb = new StringBuffer(word);
if (map.containsKey(word)) {
Map m = (Map) map.get(word);
sb.append(word);
num = i + 1;
while (true) {
if (num < txt.length()) {
word = txt.charAt(num++);
sb.append(word);
if (m.containsKey(word)){
m = (Map) m.get(word);
if (m.containsKey("isEnd")) {
has = true;
return sb.toString();
}
} else break;
} else break;
}
}
}
if (has) return sb.toString();
} catch (Exception e) {
//logger.error("检验敏感字出错，原因为：{}", e);
e.printStackTrace;
}
return null;
}
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