A Powerful Distributed Lock Framework: Introducing Lock4j

Overview

Lock4j provides distributed locking via Spring AOP (declarative) and programmatic APIs. It supports three back‑ends— RedisTemplate, Redisson, and Zookeeper —which can be mixed or extended.

Dependencies

<!-- RedisTemplate backend -->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>lock4j-redis-template-spring-boot-starter</artifactId>
    <version>2.2.4</version>
</dependency>

<!-- Redisson backend -->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>lock4j-redisson-spring-boot-starter</artifactId>
    <version>2.2.4</version>
</dependency>

Redis Configuration Example

spring:
  redis:
    database: 0
    host: 127.0.0.1
    port: 6379
    password:
    jedis:
      pool:
        max-active: 200
        max-wait: -1
        max-idle: 10
        min-idle: 0
    timeout: 6000

Lock Annotation Definition

package com.baomidou.lock.annotation;

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Lock4j {
    String name() default "";
    Class<? extends LockExecutor> executor() default LockExecutor.class;
    String[] keys() default {""};
    long expire() default -1L;
    long acquireTimeout() default -1L;
    boolean autoRelease() default true;
}

Simple Usage

@RestController
@RequestMapping("/mock")
public class MockController {
    @GetMapping("/lockMethod")
    @Lock4j(keys = {"#key"}, acquireTimeout = 1000, expire = 10000)
    public Result lockMethod(@RequestParam String key) {
        ThreadUtil.sleep(5000);
        return Result.OK(key);
    }
}

Calling http://localhost:8080/mock/lockMethod?key=123 repeatedly yields:

{
    "success": true,
    "message": "操作成功！",
    "code": 200,
    "result": "123",
    "timestamp": 1678866083211
}

If the lock cannot be obtained, Lock4j throws

com.baomidou.lock.exception.LockFailureException: request failed,please retry it.

. A global exception handler can translate this to:

{
    "success": false,
    "message": "操作失败，request failed,please retry it.",
    "code": 500,
    "result": null,
    "timestamp": 1678866034929
}

Advanced Usage

Custom Executor

@Component
public class CustomRedissonLockExecutor extends AbstractLockExecutor {
    @Override
    public Object acquire(String lockKey, String lockValue, long expire, long acquireTimeout) {
        return null;
    }
    @Override
    public boolean releaseLock(String key, String value, Object lockInstance) {
        return false;
    }
}

Specify the executor on the annotation:

@Lock4j(executor = CustomRedissonLockExecutor.class)

Custom Key Builder

@Component
public class CustomKeyBuilder extends DefaultLockKeyBuilder {
    public CustomKeyBuilder(BeanFactory beanFactory) {
        super(beanFactory);
    }
}

Custom Lock‑Failure Strategy

@Component
public class GrabLockFailureStrategy implements LockFailureStrategy {
    @Override
    public void onLockFailure(String key, Method method, Object[] arguments) {
        // custom handling logic
    }
}

The default strategy is com.baomidou.lock.DefaultLockFailureStrategy.

Manual Lock and Unlock

@Service
public class LockServiceImpl implements LockService {
    @Autowired
    private LockTemplate lockTemplate;

    @Override
    public void lock(String resourceKey) {
        LockInfo lock = lockTemplate.lock(resourceKey, 10000L, 2000L, CustomRedissonLockExecutor.class);
        if (lock == null) {
            throw new FrameworkException("业务处理中，请稍后再试...");
        }
        try {
            doBusiness();
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            lockTemplate.releaseLock(lock);
        }
    }

    private void doBusiness() {
        // TODO: business logic
    }
}

Reference

Gitee repository:

https://gitee.com/baomidou/lock4j