Spring Boot 整合 redisson 来实现分布式锁

面试时经常会问到有没有用过分布式锁、redis 锁，很多人平时很少接触到。所以只能很无奈的回答 “没有”。本文通过 Spring Boot 整合 redisson 来实现分布式锁，并结合 demo 测试结果。本来内容来自公众号“Java团长”，本人参考文章本地创建springboot项目demo进行测试，文章结尾附测试结果截图。

微信图片_20200525161825.png

<!--redis-->
<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!--redisson-->
<dependency>
        <groupId>org.redisson</groupId>
        <artifactId>redisson-spring-boot-starter</artifactId>
        <version>3.10.6</version>
</dependency>

配置信息

server.port:8080
# redis
spring.redis.host:118.126.66.195
spring.redis.port:6379
spring.redis.password:c428cb38d5f260853678922e
# 连接池最大连接数（使用负值表示没有限制）
spring.redis.jedis.pool.max-active:100
# 连接池中的最小空闲连接
spring.redis.jedis.pool.max-idle:10
# 连接池最大阻塞等待时间（使用负值表示没有限制）
spring.redis.jedis.pool.max-wait:-1
# 连接超时时间（毫秒）
spring.redis.jedis.pool.timeout:5000
#默认是索引为0的数据库
spring.redis.jedis.pool.database:0

配置类

import org.redisson.api.RedissonClient;
import org.redisson.config.Config;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.util.StringUtils;

/**
 * @Created by zl
 * @Date 2020/5/25 11:40
 * @Description
 */
@Configuration
public class RedissonConfig {
    @Value("${spring.redis.host}")
    private String host;
    @Value("${spring.redis.port}")
    private String port;
    @Value("${spring.redis.password}")
    private String password;

    @Bean
    public RedissonClient redissonClient() {
        Config config = new Config();
        //单节点
        config.useSingleServer().setAddress("redis://" + host + ":" + port);
        if (StringUtils.isEmpty(password)) {
            config.useSingleServer().setPassword(null);
        } else {
            config.useSingleServer().setPassword(password);
        }
        //添加主从配置
        // config.useMasterSlaveServers().setMasterAddress("").setPassword("").addSlaveAddress(new String[]{"",""});
        // 集群模式配置 setScanInterval()扫描间隔时间，单位是毫秒, //可以用"rediss://"来启用SSL连接
        // config.useClusterServers().setScanInterval(2000).addNodeAddress("redis://127.0.0.1:7000", "redis://127.0.0.1:7001").addNodeAddress("redis://127.0.0.1:7002");
        return Redisson.create(config);
    }
}

Redisson 工具类

package com.redis.lock.demo.util;

import com.redis.lock.demo.redis.DistributedLocker;
import org.redisson.api.RCountDownLatch;
import org.redisson.api.RLock;
import org.redisson.api.RSemaphore;

import java.util.concurrent.TimeUnit;

/**
 * @Created by zl
 * @Date 2020/5/25 11:52
 * @Description
 */
public class RedisLockUtil {
    private static DistributedLocker distributedLocker = SpringContextHolder.getBean(DistributedLocker.class);

    /**
     * 加锁
     *
     * @param lockKey
     * @return
     */
    public static RLock lock(String lockKey) {
        return distributedLocker.lock(lockKey);
    }

    /**
     * 释放锁
     *
     * @param lockKey
     */
    public static void unlock(String lockKey) {
        distributedLocker.unlock(lockKey);
    }

    /**
     * 释放锁
     *
     * @param lock
     */
    public static void unlock(RLock lock) {
        distributedLocker.unlock(lock);
    }

    /**
     * 带超时的锁
     *
     * @param lockKey
     * @param timeout 超时时间   单位：秒
     */
    public static RLock lock(String lockKey, int timeout) {
        return distributedLocker.lock(lockKey, timeout);
    }

    /**
     * 带超时的锁
     *
     * @param lockKey
     * @param unit    时间单位
     * @param timeout 超时时间
     */
    public static RLock lock(String lockKey, int timeout, TimeUnit unit) {
        return distributedLocker.lock(lockKey, unit, timeout);
    }

    /**
     * 尝试获取锁
     *
     * @param lockKey
     * @param waitTime  最多等待时间
     * @param leaseTime 上锁后自动释放锁时间
     * @return
     */
    public static boolean tryLock(String lockKey, int waitTime, int leaseTime) {
        return distributedLocker.tryLock(lockKey, TimeUnit.SECONDS, waitTime, leaseTime);
    }

    /**
     * 尝试获取锁
     *
     * @param lockKey
     * @param unit      时间单位
     * @param waitTime  最多等待时间
     * @param leaseTime 上锁后自动释放锁时间
     * @return
     */
    public static boolean tryLock(String lockKey, TimeUnit unit, int waitTime, int leaseTime) {
        return distributedLocker.tryLock(lockKey, unit, waitTime, leaseTime);
    }

    /**
     * 获取计数器
     *
     * @param name
     * @return
     */
//    public static RCountDownLatch getCountDownLatch(String name) {
//        return distributedLocker.getCountDownLatch(name);
//    }
//
//    /**
//     * 获取信号量
//     *
//     * @param name
//     * @return
//     */
//    public static RSemaphore getSemaphore(String name) {
//        return distributedLocker.getSemaphore(name);
//    }
}

底层封装

package com.redis.lock.demo.redis;

import org.redisson.api.RLock;

import java.util.concurrent.TimeUnit;

/**
 * @Created by zl
 * @Date 2020/5/25 11:53
 * @Description TODO
 */
public interface DistributedLocker {
    RLock lock(String lockKey);

    RLock lock(String lockKey, int timeout);

    RLock lock(String lockKey, TimeUnit unit, int timeout);

    boolean tryLock(String lockKey, TimeUnit unit, int waitTime, int leaseTime);

    void unlock(String lockKey);

    void unlock(RLock lock);
}

实现类

package com.redis.lock.demo.redis.impl;

import com.redis.lock.demo.redis.DistributedLocker;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.concurrent.TimeUnit;

/**
 * @Created by zl
 * @Date 2020/5/25 11:56
 * @Description TODO
 */
@Component
public class RedisDistributedLocker implements DistributedLocker {

    @Autowired
    private
    RedissonClient
            redissonClient;

    @Override
    public RLock
    lock(String lockKey) {
        RLock lock = redissonClient.getLock(lockKey);
        lock.lock();
        return lock;
    }

    @Override
    public RLock lock(String lockKey, int leaseTime) {
        RLock lock = redissonClient.getLock(lockKey);
        lock.lock(leaseTime, TimeUnit.SECONDS);
        return lock;
    }

    @Override
    public RLock
    lock(String lockKey, TimeUnit unit, int timeout) {
        RLock lock = redissonClient.getLock(lockKey);
        lock.lock(timeout, unit);
        return lock;
    }

    @Override
    public boolean
    tryLock(String lockKey, TimeUnit unit, int waitTime, int leaseTime) {
        RLock lock = redissonClient.getLock(lockKey);
        try {
            return lock.tryLock(waitTime, leaseTime, unit);
        } catch (InterruptedException e) {
            return false;
        }
    }

    @Override
    public void
    unlock(String lockKey) {
        RLock lock = redissonClient.getLock(lockKey);
        lock.unlock();
    }

    @Override
    public void unlock(RLock lock) {
        lock.unlock();
    }
}

SpringContextHolder类

package com.redis.lock.demo.util;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

/**
 * Spring的ApplicationContext的持有者,可以用静态方法的方式获取spring容器中的bean
 *
 * @author zl
 * @date 2020年05月25日 下午14:05:11
 */
@Component
public class SpringContextHolder implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        SpringContextHolder.applicationContext = applicationContext;
    }

    public static ApplicationContext getApplicationContext() {
        assertApplicationContext();
        return applicationContext;
    }

    @SuppressWarnings("unchecked")
    public static <T> T getBean(String beanName) {
        assertApplicationContext();
        return (T) applicationContext.getBean(beanName);
    }

    public static <T> T getBean(Class<T> requiredType) {
        assertApplicationContext();
        return applicationContext.getBean(requiredType);
    }

    private static void assertApplicationContext() {
        if (SpringContextHolder.applicationContext == null) {
            throw new RuntimeException("applicaitonContext属性为null,请检查是否注入了SpringContextHolder!");
        }
    }

}

controller测试类

package com.redis.lock.demo.controller;

import com.redis.lock.demo.util.RedisLockUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

/**
 * @Created by zl
 * @Date 2020/5/25 13:45
 * @Description
 */
@RestController
@RequestMapping("/redisson")
@Slf4j
public class RedissonLockController {
    /**
     * 锁测试共享变量
     */
    private
    Integer lockCount = 30;

    /**
     * 无锁测试共享变量
     */
    private Integer count = 30;

    /**
     * 模拟线程数
     */
    private static int threadNum = 30;

    /**
     * 模拟并发测试加锁和不加锁
     *
     * @return
     */
    @GetMapping("/test")
    public void lock() {
        // 计数器
        final CountDownLatch countDownLatch = new CountDownLatch(1);
        for (int i = 0; i < threadNum; i++) {
            MyRunnable myRunnable = new MyRunnable(countDownLatch);
            Thread myThread = new Thread(myRunnable);
            myThread.start();
        }
        // 释放所有线程
        countDownLatch.countDown();
    }

    /**
     * 加锁测试
     */
    private void testLockCount() {
        String lockKey = "lock-test";
        try {
            // 加锁，设置超时时间2s
            RedisLockUtil.lock(lockKey, 2, TimeUnit.SECONDS);
            lockCount--;
            log.info("lockCount值：" + lockCount);
        } catch
        (Exception e) {
            log.error(e.getMessage(), e);
        } finally {
            // 释放锁
            RedisLockUtil.unlock(lockKey);
        }
    }

    /**
     * 无锁测试
     */
    private void testCount() {
        count--;
        log.info("count值：" + count);
    }


    public class MyRunnable implements Runnable {
        /**
         * 计数器
         */
        final CountDownLatch countDownLatch;

        public MyRunnable(CountDownLatch countDownLatch) {
            this.countDownLatch = countDownLatch;
        }

        @Override
        public void run() {
            try {
                // 阻塞当前线程，直到计时器的值为0
                countDownLatch.await();
            } catch (InterruptedException e) {
                log.error(e.getMessage(), e);
            }
            // 无锁操作
            testCount();
            // 加锁操作
            testLockCount();
        }

    }
}

结果示例图

image.png

测试结果
根据打印结果可以明显看到，未加锁的 count-- 后值是乱序的，而加锁后的结果是按照顺序排序的和我们预期的一样。