关键字过滤高效算法

来源：互联网发布：2016淘宝销售排行榜编辑：程序博客网时间：2024/05/17 23:48
import java.util.ArrayList;import java.util.HashMap;import java.util.HashSet;import java.util.List;import java.util.Set;@SuppressWarnings({ "rawtypes", "unchecked" })public class KeywordFilter {/** 直接禁止的 */private HashMap keysMap = new HashMap();private int matchType = 1; // 1:最小长度匹配 2：最大长度匹配public void addKeywords(List<String> keywords) {for (int i = 0; i < keywords.size(); i++) {String key = keywords.get(i).trim();HashMap nowhash = null;nowhash = keysMap;for (int j = 0; j < key.length(); j++) {char word = key.charAt(j);Object wordMap = nowhash.get(word);if (wordMap != null) {nowhash = (HashMap) wordMap;} else {HashMap<String, String> newWordHash = new HashMap<String, String>();newWordHash.put("isEnd", "0");nowhash.put(word, newWordHash);nowhash = newWordHash;}if (j == key.length() - 1) {nowhash.put("isEnd", "1");}}}}/** * 重置关键词 */public void clearKeywords() {keysMap.clear();}/** * 检查一个字符串从begin位置起开始是否有keyword符合， 如果有符合的keyword值，返回值为匹配keyword的长度，否则返回零 * flag 1:最小长度匹配 2：最大长度匹配 */private int checkKeyWords(String txt, int begin, int flag) {HashMap nowhash = null;nowhash = keysMap;int maxMatchRes = 0;int res = 0;int l = txt.length();char word = 0;for (int i = begin; i < l; i++) {word = txt.charAt(i);Object wordMap = nowhash.get(word);if (wordMap != null) {res++;nowhash = (HashMap) wordMap;if (((String) nowhash.get("isEnd")).equals("1")) {if (flag == 1) {wordMap = null;nowhash = null;txt = null;return res;} else {maxMatchRes = res;}}} else {txt = null;nowhash = null;return maxMatchRes;}}txt = null;nowhash = null;return maxMatchRes;}/** * 返回txt中关键字的列表 */public Set<String> getTxtKeyWords(String txt) {Set set = new HashSet();int l = txt.length();for (int i = 0; i < l;) {int len = checkKeyWords(txt, i, matchType);if (len > 0) {set.add(txt.substring(i, i + len));i += len;} else {i++;}}txt = null;return set;}/** * 仅判断txt中是否有关键字 */public boolean isContentKeyWords(String txt) {for (int i = 0; i < txt.length(); i++) {int len = checkKeyWords(txt, i, 1);if (len > 0) {return true;}}txt = null;return false;}public int getMatchType() {return matchType;}public void setMatchType(int matchType) {this.matchType = matchType;}public static void main(String[] args) {KeywordFilter filter = new KeywordFilter();List<String> keywords = new ArrayList<String>();keywords.add("中国人");keywords.add("中国");filter.addKeywords(keywords);String txt = "中国人民站起来了";boolean boo = filter.isContentKeyWords(txt);System.out.println(boo);Set set = filter.getTxtKeyWords(txt);System.out.println(set);}}
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