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        Redisson 是一种基于 Redis 的 Java 驻留集群的分布式对象和服务库，可以为我们提供丰富的分布式锁和线程安全集合的实现。在 Spring Boot 应用程序中使用 Redisson 可以方便地实现分布式应用程序的某些方面，例如分布式锁、分布式集合、分布式事件发布和订阅等。本篇是一个使用 Redisson 实现分布式锁的详细示例，在这个示例中，我们定义了DistributedLock注解，它可以标注在方法上，配合DistributedLockAspect切面以及IDistributedLock分布式锁封装的接口，来实现redisson 分布式锁的 API 调用。

Spring Boot 集成 Redisson

 1、在 pom.xml 文件中添加 Redisson 的相关依赖

<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-boot-starter</artifactId>
    <version>3.16.1</version>
</dependency>

2、在 application.yml 中配置 Redisson单机模式 的连接信息和相关参数

spring:
  redis:
    host: localhost
    port: 6379
    password: null
redisson:
  codec: org.redisson.codec.JsonJacksonCodec
  threads: 4
  netty:
    threads: 4
  single-server-config:
    address: "redis://localhost:6379"
    password: null
    database: 0

3、Redission还支持主从、集群、哨兵配置

//主从模式
spring:
  redis:
    sentinel:
      master: my-master
      nodes: localhost:26379,localhost:26389
    password: your_password
redisson:
  master-slave-config:
    master-address: "redis://localhost:6379"
    slave-addresses: "redis://localhost:6380,redis://localhost:6381"
    password: ${spring.redis.password}

// 集群模式
spring:
  redis:
    cluster:
      nodes: localhost:6379,localhost:6380,localhost:6381,localhost:6382,localhost:6383,localhost:6384
    password: your_password
redisson:
  cluster-config:
    node-addresses: "redis://localhost:6379,redis://localhost:6380,redis://localhost:6381,redis://localhost:6382,redis://localhost:6383,redis://localhost:6384"
    password: ${spring.redis.password}

// 哨兵模式
spring:
  redis:
    sentinel:
      master: my-master
      nodes: localhost:26379,localhost:26389
    password: your_password
redisson:
  sentinel-config:
    master-name: my-master
    sentinel-addresses: "redis://localhost:26379,redis://localhost:26380,redis://localhost:26381"
    password: ${spring.redis.password}

 本地封装Redisson 分布式锁

1、定义IDistributedLock分布式锁接口

import java.util.concurrent.TimeUnit;

/**
 * <p>
 * </p>
 * @since 2023-06-08 16:54
 */
public interface IDistributedLock {
    /**
     * 获取锁，默认30秒失效，失败一直等待直到获取锁
     *
     * @param key 锁的key
     * @return 锁对象
     */
    ILock lock(String key);

    /**
     * 获取锁,失败一直等待直到获取锁
     *
     * @param key      锁的key
     * @param lockTime 加锁的时间，超过这个时间后锁便自动解锁； 如果lockTime为-1，则保持锁定直到显式解锁
     * @param unit     {@code lockTime} 参数的时间单位
     * @param fair     是否公平锁
     * @return 锁对象
     */
    ILock lock(String key, long lockTime, TimeUnit unit, boolean fair);

    /**
     * 尝试获取锁，30秒获取不到超时异常，锁默认30秒失效
     *
     * @param key 锁的key
     * @return
     * @throws Exception
     */
    ILock tryLock(String key) throws Exception;

    /**
     * 尝试获取锁，获取不到超时异常
     *
     * @param key      锁的key
     * @param tryTime  获取锁的最大尝试时间
     * @param lockTime 加锁的时间
     * @param unit     {@code tryTime @code lockTime} 参数的时间单位
     * @param fair     是否公平锁
     * @return
     * @throws Exception
     */
    ILock tryLock(String key, long tryTime, long lockTime, TimeUnit unit, boolean fair) throws Exception;

    /**
     * 解锁
     *
     * @param lock
     * @throws Exception
     */
    void unLock(Object lock);

    /**
     * 释放锁
     *
     * @param lock
     * @throws Exception
     */
    default void unLock(ILock lock) {
        if (lock != null) {
            unLock(lock.getLock());
        }
    }
}

2、IDistributedLock实现类

import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;

/**
 * <p>     </p>
 * @since 2023-06-08 16:57
 */
@Component
public class RedissonDistributedLock implements IDistributedLock {

    @Resource
    private RedissonClient redissonClient;
    /**
     * 统一前缀
     */
    @Value("${redisson.lok.prefix:bi-distributed-lock}")
    private String prefix;

    @Override
    public ILock lock(String key) {
        return this.lock(key, 30L, TimeUnit.SECONDS, false);
    }

    @Override
    public ILock lock(String key, long lockTime, TimeUnit unit, boolean fair) {
        RLock lock;
        String lockKey = prefix + ":" + key;
        if (fair) {
            // 获取公平锁
            lock = redissonClient.getFairLock(lockKey);
        } else {
            // 获取普通锁
            lock = redissonClient.getLock(lockKey);
        }
        // 获取锁,失败一直等待,直到获取锁
        lock.lock(lockTime, unit);
        return new ILock(lock, this);
    }

    @Override
    public ILock tryLock(String key) throws Exception {
        return this.tryLock(key, 30L, 30l, TimeUnit.SECONDS, false);
    }

    @Override
    public ILock tryLock(String key, long tryTime, long lockTime, TimeUnit unit, boolean fair)
            throws Exception {
        RLock lock;
        String lockKey = prefix + ":" + key;
        if (fair) {
            // 获取公平锁
            lock = redissonClient.getFairLock(lockKey);
        } else {
            // 获取普通锁
            lock = redissonClient.getLock(lockKey);
        }
        lock.lock();
        // 尝试获取锁，获取不到超时异常
        if (lock.tryLock(tryTime, lockTime, unit)) {
            return new ILock(lock, this);
        }
        return null;
    }

    @Override
    public void unLock(Object lock) {
        if (lock != null) {
            if (lock instanceof RLock) {
                RLock l = (RLock) lock;
                if (l.isLocked()) {
                    l.unlock();
                }
            }
        }
    }
}

 3、定义ILock锁对象

import lombok.AllArgsConstructor;
import lombok.Getter;

import java.util.Objects;

/**
 * <p>
 * RedissonLock 包装的锁对象 实现AutoCloseable接口，在java7的try(with resource)语法，不用显示调用close方法
 * </p>

 * @since 2023-06-08 16:57
 */
@AllArgsConstructor
public class ILock implements AutoCloseable {
    /**
     * 持有的锁对象
     */
    @Getter
    private Object lock;
    /**
     * 分布式锁接口
     */
    @Getter
    private IDistributedLock distributedLock;

    @Override
    public void close() throws Exception {
        if(Objects.nonNull(lock)){
            distributedLock.unLock(lock);
        }
    }
}

4、注入IDistributedLock接口使用示例

// 定义接口
public interface IProductSkuSupplierMeasureService {
    /**
     * 保存SKU供应商供货信息
     *
     * @param dto
     * @return
     *
    Boolean saveSupplierInfo(ProductSkuSupplierInfoDTO dto);

    /**
     * 编辑SKU供应商供货信息
     *
     * @param dto
     * @return
     */
    Boolean editSupplierInfo(ProductSkuSupplierInfoDTO dto);
}    

手动释放锁示例 

// 实现类
@Service
public class ProductSkuSupplierMeasureServiceImpl 
        implements IProductSkuSupplierMeasureService {

    @Resource
    private IDistributedLock distributedLock;    
    
    @Override
    @Transactional(rollbackFor = Exception.class)
    public Boolean saveSupplierInfo(ProductSkuSupplierInfoDTO dto) {
        // 手动释放锁
        String sku = dto.getSku();
        ILock lock = null;
        try {
            lock = distributedLock.lock(dto.getSku(),10L, TimeUnit.SECONDS, false);
            // 业务代码
        } catch (Exception e) {
            log.error("保存异常", e);
            throw new BaseException(e.getMessage());
        } finally {
            if (Objects.nonNull(lock)) {
                distributedLock.unLock(lock);
            }
        }
        return Boolean.TRUE;
    }

}

 使用try-with-resources 语法糖自动释放锁

// 实现类
@Service
public class ProductSkuSupplierMeasureServiceImpl 
        implements IProductSkuSupplierMeasureService {

    @Resource
    private IDistributedLock distributedLock;    
   

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Boolean editSupplierInfo(ProductSkuSupplierInfoDTO dto) {
       
        String sku = dto.getSku();
        // try-with-resources 语法糖自动释放锁
        try(ILock lock = distributedLock.lock(dto.getSku(),10L, TimeUnit.SECONDS, false)) {
            if(Objects.isNull(lock)){
                throw new IdempotencyException("Duplicate request for method still in process");
            }
            
            // 业务代码
        } catch (Exception e) {
            log.error("异常", e);
           throw new BaseException(e.getMessage());
        }
        return Boolean.TRUE;
   }
}

5、使用AOP切面实现分布式锁的绑定

  定义DistributedLock注解

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DistributedLock {

    /**
     * 保证业务接口的key的唯一性，否则失去了分布式锁的意义 锁key
     * 支持使用spEl表达式
     */
    String key();

    /**
     * 保证业务接口的key的唯一性，否则失去了分布式锁的意义 锁key 前缀
     */
    String keyPrefix() default "";

    /**
     * 获取锁的最大尝试时间 该值大于0，则会尝试tryTime时间，在该时间内获取成功则返回，否则抛出获取锁超时异常
     * 该值等于小于0时尝试获取锁,失败一直等待，直到获取锁  --默认
     */
    long tryTime() default 0;

    /**
     * 加锁的时间，超过这个时间后锁便自动解锁
     */
    long lockTime() default 30;

    /**
     * tryTime 和 lockTime的时间单位
     */
    TimeUnit unit() default TimeUnit.SECONDS;

    /**
     * 是否公平锁，false:非公平锁，true:公平锁
     */
    boolean fair() default false;
}

 定义DistributedLockAspect Lock切面

@Aspect
@Slf4j
public class DistributedLockAspect {

    @Resource
    private IDistributedLock distributedLock;

    /**
     * 统一前缀
     */
    @Value("${redisson.lok.prefix:bi:distributed:lock}")
    private String prefix;

    /**
     * SpEL表达式解析
     */
    private SpelExpressionParser spelExpressionParser = new SpelExpressionParser();

    /**
     * 用于获取方法参数名字
     */
    private DefaultParameterNameDiscoverer nameDiscoverer = new DefaultParameterNameDiscoverer();

    @Pointcut("@annotation(com.yt.bi.common.redis.distributedlok.annotation.DistributedLock)")
    public void distributorLock() {
    }

    @Around("distributorLock()")
    public Object around(ProceedingJoinPoint pjp) throws Throwable {
        // 获取DistributedLock
        DistributedLock distributedLock = this.getDistributedLock(pjp);
        // 获取 lockKey
        String lockKey = this.getLockKey(pjp, distributedLock);
        ILock lockObj = null;
        try {
            // 加锁
            if (distributedLock.tryTime() > 0) {
                lockObj = this.distributedLock.tryLock(lockKey, distributedLock.tryTime(), distributedLock.lockTime(), distributedLock.unit(), distributedLock.fair());
            } else {
                lockObj = this.distributedLock.lock(lockKey, distributedLock.lockTime(), distributedLock.unit(), distributedLock.fair());
            }

            if (Objects.isNull(lockObj)) {
                throw new IdempotencyException("Duplicate request for method still in process");
            }

            return pjp.proceed();
        } catch (Exception e) {
            throw e;
        } finally {
            // 解锁
            this.unLock(lockObj);
        }
    }

    /**
     * @param pjp
     * @return
     * @throws NoSuchMethodException
     */
    private DistributedLock getDistributedLock(ProceedingJoinPoint pjp) throws NoSuchMethodException {
        String methodName = pjp.getSignature().getName();
        Class clazz = pjp.getTarget().getClass();
        Class<?>[] par = ((MethodSignature) pjp.getSignature()).getParameterTypes();
        Method lockMethod = clazz.getMethod(methodName, par);
        DistributedLock distributedLock = lockMethod.getAnnotation(DistributedLock.class);
        return distributedLock;
    }

    /**
     * 解锁
     *
     * @param lockObj
     */
    private void unLock(ILock lockObj) {
        if (Objects.isNull(lockObj)) {
            return;
        }

        try {
            this.distributedLock.unLock(lockObj);
        } catch (Exception e) {
            log.error("分布式锁解锁异常", e);
        }
    }

    /**
     * 获取 lockKey
     *
     * @param pjp
     * @param distributedLock
     * @return
     */
    private String getLockKey(ProceedingJoinPoint pjp, DistributedLock distributedLock) {
        String lockKey = distributedLock.key();
        String keyPrefix = distributedLock.keyPrefix();
        if (StringUtils.isBlank(lockKey)) {
            throw new IdempotencyException("Lok key cannot be empty");
        }
        if (lockKey.contains("#")) {
            this.checkSpEL(lockKey);
            MethodSignature methodSignature = (MethodSignature) pjp.getSignature();
            // 获取方法参数值
            Object[] args = pjp.getArgs();
            lockKey = getValBySpEL(lockKey, methodSignature, args);
        }
        lockKey = StringUtils.isBlank(keyPrefix) ? prefix + ":" + lockKey : prefix + ":" + keyPrefix + lockKey;
        return lockKey;
    }

    /**
     * 解析spEL表达式
     *
     * @param spEL
     * @param methodSignature
     * @param args
     * @return
     */
    private String getValBySpEL(String spEL, MethodSignature methodSignature, Object[] args) {
        // 获取方法形参名数组
        String[] paramNames = nameDiscoverer.getParameterNames(methodSignature.getMethod());
        if (paramNames == null || paramNames.length < 1) {
            throw new IdempotencyException("Lok key cannot be empty");
        }
        Expression expression = spelExpressionParser.parseExpression(spEL);
        // spring的表达式上下文对象
        EvaluationContext context = new StandardEvaluationContext();
        // 给上下文赋值
        for (int i = 0; i < args.length; i++) {
            context.setVariable(paramNames[i], args[i]);
        }
        return expression.getValue(context).toString();
    }

    /**
     * SpEL 表达式校验
     *
     * @param spEL
     * @return
     */
    private void checkSpEL(String spEL) {
        try {
            ExpressionParser parser = new SpelExpressionParser();
            parser.parseExpression(spEL, new TemplateParserContext());
        } catch (Exception e) {
            log.error("spEL表达式解析异常", e);
            throw new IdempotencyException("Invalid SpEL expression [" + spEL + "]");
        }
    }
}

定义分布式锁注解版启动元注解

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import({DistributedLockAspect.class})
public @interface EnableDistributedLock {
}

6、AOP切面实现分布式锁的绑定使用示例

   启动类添加@EnableDistributedLock启用注解支持

@SpringBootApplication
@EnableDistributedLock
public class BiCenterGoodsApplication {

    public static void main(String[] args) {
        
        SpringApplication.run(BiCenterGoodsApplication.class, args);
        
    }
}

@DistributedLock标注需要使用分布式锁的方法 

    @ApiOperation("编辑SKU供应商供货信息")
    
    @PostMapping("/editSupplierInfo")
    //@DistributedLock(key = "#dto.sku + '-' + #dto.skuId", lockTime = 10L, keyPrefix = "sku-")
    @DistributedLock(key = "#dto.sku", lockTime = 10L, keyPrefix = "sku-")
    public R<Boolean> editSupplierInfo(@RequestBody @Validated ProductSkuSupplierInfoDTO dto) {
        return R.ok(productSkuSupplierMeasureService.editSupplierInfo(dto));
    }

#dto.sku是 SpEL表达式。Spring中支持的它都支持的。比如调用静态方法，三目表达式。SpEL 可以使用方法中的任何参数。SpEL表达式参考