問(wèn)題發(fā)布功能的重點(diǎn)在于如何實(shí)現(xiàn)敏感詞過(guò)濾，基本的算法是前綴樹(shù)算法，前綴樹(shù)也就是字典樹(shù)，通過(guò)前綴樹(shù)匹配可以加快敏感詞匹配的速度
下面是具體的代碼

• 前綴樹(shù)的結(jié)構(gòu)
  其中包括有是否為結(jié)尾的標(biāo)志符end，當(dāng)在樹(shù)中找到這個(gè)位置時(shí)，說(shuō)明找到了敏感詞，可以將其打碼設(shè)為**,從后面的字符繼續(xù)匹配

   private class TrieNode {
        private boolean end = false;
        private Map<Character, TrieNode> map = new HashMap<Character, TrieNode>();
        private Character c;

        TrieNode() {
        }

        TrieNode(Character ch) {
            c = ch;
        }

        public Character getch() {
            return c;
        }

        public void setend(boolean a) {
            this.end = a;
        }

        public boolean getend() {
            return end;
        }

        public void addTrieNode(TrieNode tn) {
            map.put(tn.getch(), tn);
        }

        public TrieNode getTrieNode(Character key) {
            return map.get(key);
        }

    }

• 前綴樹(shù)的生成（從txt文件中讀取，每讀到一個(gè)詞語(yǔ)（一個(gè)詞語(yǔ)一行），利用addword來(lái)添加)
  注意：這里該類implements InitializingBean其中的一個(gè)函數(shù)——public void afterPropertiesSet() throws Exception,這個(gè)函數(shù)表示在實(shí)例化bean之后，即Bean屬性注入之后，執(zhí)行的操作，我們通過(guò)這個(gè)函數(shù)，在每次注入該服務(wù)時(shí)，能夠初始化前綴樹(shù)

    @Override
    public void afterPropertiesSet() throws Exception {
        rootNode = new TrieNode();
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("C:\\Users\\erika\\Videos\\offer\\askme\\src\\main\\resources\\SensitiveWords.txt")),
                    "UTF-8"));
            String lineTxt = null;
            while ((lineTxt = br.readLine()) != null) {
                addword(lineTxt.trim());

                System.out.println(lineTxt);
            }
            br.close();
        } catch (Exception e) {
            logger.error("讀取文件失敗" + e);
            System.out.println("111");
        }

    }

• 向前綴樹(shù)中添加詞語(yǔ)（每個(gè)字占一個(gè)節(jié)點(diǎn)）

    public void addword(String word) {
        TrieNode tmp = rootNode;
        for (int i = 0; i < word.length(); i++) {
            if (isSymbol(word.charAt(i)))
                continue;
            if (tmp.getTrieNode(word.charAt(i)) != null) ;
            else {
                TrieNode tt = new TrieNode(word.charAt(i));
                tmp.addTrieNode(tt);
            }
            tmp = tmp.getTrieNode(word.charAt(i));
            if (i == word.length() - 1) {
                tmp.setend(true);
            }
        }
    }

• filter匹配字符串

    public String filterword(String content) {
        TrieNode root = rootNode;
        TrieNode tmp = root;
        StringBuilder result = new StringBuilder();
        int head = 0;
        int current = 0;
        while (head < content.length()) {
            Character c = content.charAt(head);
            tmp = root;
            if (isSymbol(c)) {
                head++;
                current++;
                result.append(c);
                continue;
            }
            boolean flag = false;
            while (current < content.length() && tmp.getTrieNode(c) != null) {
                if (tmp.getTrieNode(c).getend()) {
                    result.append("**");
                    flag = true;
                    break;
                }
                current++;
                tmp = tmp.getTrieNode(c);
                while(current<content.length() && isSymbol(content.charAt(current))) {
                    current++;
                    continue;
                }
                c = content.charAt(current);

            }
            if (flag) {
                current++;
                head = current;
            } else {
                result.append(content.charAt(head));
                head++;
                current = head;
            }
        }
        return result.toString();
    }

• 一個(gè)輔助函數(shù)，用來(lái)判斷字符是否為空格，或者特殊字符

    private boolean isSymbol(char c) {
        int ic = (int) c;
        Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
        //判斷是否為中文標(biāo)點(diǎn)
        if (ub == Character.UnicodeBlock.GENERAL_PUNCTUATION
                || ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
                || ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS
                || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_FORMS
                || ub == Character.UnicodeBlock.VERTICAL_FORMS)
            return true;
        // 0x2E80-0x9FFF 東亞文字范圍
        return Character.isSpaceChar(c)||(!CharUtils.isAsciiAlphanumeric(c) && (ic < 0x2E80 || ic > 0x9FFF));
    }