mqtt topic规则校验java实现

/**
 * @author 刘靖
 */
public class TopicUtils {

    public static void main(String[] args) {
        // 规则topic
        String topicRule = "aa/+/bb/+/+/cc/#";
        // 目标topic
        String topic = "aa/11/bb/2222/4444/cc/5555//";
        System.out.println("是否匹配：" + match(topicRule, topic));

        topicRule = "+";
        topic = "aa";
        System.out.println("是否匹配：" + match(topicRule, topic));

        topicRule = "+/#";
        topic = "aa/cc/dd";
        System.out.println("是否匹配：" + match(topicRule, topic));

        topicRule = "/+/";
        topic = "/aa/";
        System.out.println("是否匹配：" + match(topicRule, topic));

        topicRule = "aa/#";
        topic = "aa";
        System.out.println("是否匹配：" + match(topicRule, topic));
    }

    /**
     * 匹配mqtt topic
     * @param topicRule 匹配规则
     * @param topic 目标topic
     * @return
     */
    public static boolean match(String topicRule, String topic) {
        char[] topicRuleChar = topicRule.toCharArray();
        char[] topicChar = topic.toCharArray();
        // topic的字符指针，用来表示当前判断到了哪个位置的字符
        int topicIndex = 0;

        ruleSign:
        for (int i = 0; i < topicRuleChar.length; i++) {

            char indexRuleChar = topicRuleChar[i];

            // 如果满足 '/#' 格式，则说明topic匹配
            if (indexRuleChar == '#' && topicRuleChar[i - 1] == '/'){
                return true;
            }

            // 如果已经到达目标字符串末尾，但是规则字符串当前还不是通配符 '+' 则表示匹配失败
            if (topicIndex == topicChar.length){
                if (i + 2 == topicRuleChar.length && topicRuleChar[i] == '/' && topicRuleChar[i + 1] == '#'){
                    return true;
                }
                if (indexRuleChar != '+'){
                    return false;
                }
            }
            // 判断当前字符是否相等，如果相等直接跳到下一个字符，并向后移动一格topicIndex指针
            if (topicIndex != topicChar.length && indexRuleChar == topicChar[topicIndex]){
                topicIndex++;
                continue;
            }

            /*
                '+' 符号通配符判断，如果当前字符为+号，有四种情况满足单层通配符要求：
                1.当前字符为第一个字符，且后一个字符为 '/'
                2.当前字符为中间字符，且前后字符均为 '/'
                3.当前字符未末尾字符，且前一个字符未 '/'
                4.整个字符串都只有当前一个字符
             */
            if (indexRuleChar == '+'){
                if (topicRuleChar.length == 1){
                    // 满足整个topicRule = '+'
                    // 判断topic是否为单层，不为单层直接不匹配(遇到'/'符号表示不匹配)
                    for (int j = 0; j < topicChar.length; j++) {
                        if (topicChar[j] == '/'){
                            return false;
                        }
                    }
                    return true;
                }else if (i == 0 && topicRuleChar[i + 1] == '/'){
                    // 满足topicRule = '+/' 开头
                    // 将topicIndex指针移动到下一个'/'符号位置，并结束当前判断
                    for (int j = topicIndex; j < topicChar.length; j++) {
                        if (topicChar[j] == '/'){
                            topicIndex = j;
                            continue ruleSign;
                        }
                    }
                    return false;
                }else if (i != 0 && topicRuleChar[i - 1] == '/'){
                    if (topicRuleChar.length - 1 <= i){
                        // 满足topicRule 以 '/+' 结尾
                        // 但凡后面还有 '/' 符号，代表不匹配
                        for (int j = topicIndex; j < topicChar.length; j++) {
                            if (topicChar[j] == '/'){
                                return false;
                            }
                        }
                        return true;
                    }else if (topicRuleChar[i + 1] == '/'){
                        // 满足topicRule 包含 '/+/'
                        for (int j = topicIndex; j < topicChar.length; j++) {
                            if (topicChar[j] == '/'){
                                topicIndex = j;
                                continue ruleSign;
                            }
                        }
                        return false;
                    }
                }
            }
            // 不满足'+'通配符
            return false;
        }
        // 如果判断完rule的每个字符，目标topic还未到达尾部，则说明不匹配
        if (topicIndex < topicChar.length){
            return false;
        }
        return true;
    }


}