基于Redis分布式锁Redisson及SpringBoot集成Redisson

2022-11-13 17:11:26 redis 分布式 集成

- 分布式锁需要具备的条件和刚需

  • 独占性:OnlyOne,任何时刻只能有且仅有一个线程持有
  • 高可用:若redis集群环境下,不能因为某一个节点挂了而出现获取锁和释放锁失败的情况
  • 防死锁:杜绝死锁,必须有超时控制机制或者撤销操作,有个兜底终止跳出方案
  • 不乱抢:防止张冠李戴,不能私下unlock别人的锁,只能自己加锁自己释放
  • 重入性:同一个节点的同一个线程如果获得锁之后,它也可以再次获取这个锁

- Redisson使用

引入 redisson 依赖:

<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson</artifactId>
    <version>3.16.2</version>
</dependency>

添加 redisson 配置:

import org.redisson.Redisson;
import org.redisson.config.Config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JSONRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import java.io.Serializable;

@Configuration
public class RedisConfig {
    @Bean
    public RedisTemplate<String, Serializable> redisTemplate(LettuceConnectionFactory lettuceConnectionFactory) {
        RedisTemplate<String, Serializable> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(lettuceConnectionFactory);
        // 设置key序列号方式string
        redisTemplate.seTKEySerializer(new StringRedisSerializer());
        // 设置value的序列化方式json
        redisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer());
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());
        redisTemplate.afterPropertiesSet();
        return redisTemplate;
    }
    @Bean
    public Redisson redisson() {
        Config config = new Config();
        config.useSingleServer().setAddress("redis://192.168.10.233:6379").setDatabase(0);
        return (Redisson) Redisson.create(config);
    }

}

接口测试:

import org.redisson.Redisson;
import org.redisson.api.RLock;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.WEB.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {

    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @Autowired
    private Redisson redisson;

    private static final String KEY = "spike";

    @GetMapping("/buy")
    public String bugGood() {
        RLock redissonLock = redisson.getLock(KEY);
        redissonLock.lock();
        try {
            String result = stringRedisTemplate.opsForValue().get("goods:001");
            int goodNumber = result == null ? 0 : Integer.parseInt(result);
            if (goodNumber > 0) {
                int realNum = goodNumber - 1;
                stringRedisTemplate.opsForValue().set("goods:001", realNum + "");
                return "秒杀成功,剩余库存:" + realNum;
            }
            return "商品已售罄!";
        } finally {
            redissonLock.unlock();
        }
    }

}

多节点的情况下,代码相同,要保证 lock 的 key 一样

- SpringBoot集成Redisson

引入 redis 和 redisson starter:

<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-data-redis -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!-- Https://mvnrepository.com/artifact/org.redisson/redisson -->
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-boot-starter</artifactId>
</dependency>

redis 配置:

spring:
  redis:
    # 地址
    host: 192.168.20.26
    # 端口,默认为6379
    port: 6379
    passWord: 123456
    # 连接超时时间
    timeout: 30s
    database: 0
    lettuce:
      pool:
        # 连接池中的最小空闲连接
        min-idle: 0
        # 连接池中的最大空闲连接
        max-idle: 8
        # 连接池的最大数据库连接数
        max-active: 8
        # #连接池最大阻塞等待时间(使用负值表示没有限制)
        max-wait: -1ms

redisson配置:

import org.redisson.Redisson;
import org.redisson.api.RedissonClient;
import org.redisson.config.Config;
import org.redisson.config.SingleServerConfig;
import org.redisson.config.TransportMode;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;


@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();
        config.setTransportMode(TransportMode.NIO);
        // 单体配置,如果是SSL连接,使用 rediss://
        SingleServerConfig singleServerConfig = config.useSingleServer();
        singleServerConfig.setAddress("redis://" + host + ":" + port);
        singleServerConfig.setPassword(password);
        return Redisson.create(config);
    }
}

使用:

import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;
public class TestController {

    @Resource
    private RedissonClient redissonClient;

    public void doAction1() {
        String lockKey = "lockKey";
        RLock lock = redissonClient.getLock(lockKey);
        // 加锁,无参数
        lock.lock();
        // 锁有效时间,时间单位
        // lock.lock(5, TimeUnit.SECONDS);
        try {
            // do something
        } finally {
            // 解锁
            lock.unlock();
        }
    }
    public void doAction2() throws InterruptedException {
        String lockKey = "lockKey";
        RLock lock = redissonClient.getLock(lockKey);
        // 1. 无参数,直接上锁
        // lock.tryLock();
        // 2. 等待时间,时间单位
        // lock.tryLock(3, TimeUnit.SECONDS);
        // 3. 等待时间,锁有效时间,时间单位
        // lock.tryLock(3, 5, TimeUnit.SECONDS);
        try {
            // 常规写法
            if (lock.tryLock(3, 5, TimeUnit.SECONDS)) {
                // do something
            } else {
                // 没有获取到锁
            }
        } finally {
            // 解锁
            lock.unlock();
        }
    }

}

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