synchronized 使用 String 做锁定互斥

背景

根据方法传入的字符串，做相同字符串的互斥操作

思路

• 1、使用 string.intern() 方法 -- 不推荐
• 2、自己定义个工厂

自己使用工厂实现

实现

package com.example.demo;

import lombok.Data;
import org.springframework.util.StringUtils;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;


public class MutexFactory {
    private static final int DEFAULT_MUTEX_MAP_SIZE = 32;
    private static final String DEFAULT_KEY = "default";
    
    private static ConcurrentMap globalMutexMap = new ConcurrentHashMap<>(DEFAULT_MUTEX_MAP_SIZE);

    private MutexFactory() {

    }

    public static Mutex getMutex(String key) {
        String finalKey = handleKey(key);
        return globalMutexMap.compute(key, (k, v) -> (v == null) ? new Mutex(finalKey) : v);
    }

    private static String handleKey(String key) {
        if (StringUtils.isEmpty(key)) {
            return DEFAULT_KEY;
        } else {
            return key;
        }
    }

    @Data
    static class Mutex {
        private String value;

        public Mutex(String value) {
            this.value = value;
        }
    }
}

使用

synchronized (MutexFactory.getMutex(key)){
            System.out.println("handle:" +key);
}