Guide to Using Lock4j Distributed Lock Component in Spring Boot

Introduction Lock4j is a distributed lock component that supports multiple back‑ends such as RedisTemplate , Redisson and Zookeeper , offering both declarative (Spring AOP) and programmatic lock usage.

Features - Simple to use, powerful, and highly extensible. - Supports mixing redisson , redisTemplate , and zookeeper back‑ends.

Preparation before Use

Add Dependencies

com.baomidou
lock4j-redis-template-spring-boot-starter
2.2.4
com.baomidou
lock4j-redisson-spring-boot-starter
2.2.4

Add Redis Configuration

spring:
  redis:
    database: 0
    # Redis server address
    host: 127.0.0.1
    # Redis server port
    port: 6379
    # Password (empty by default)
    password:
    jedis:
      pool:
        max-active: 200
        max-wait: -1
        max-idle: 10
        min-idle: 0
        timeout: 6000

Annotation Attribute Description

package com.baomidou.lock.annotation;

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Lock4j {
    String name() default "";
    Class
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);
    }
}

Access http://localhost:8080/mock/lockMethod?key=123 repeatedly. When the lock is acquired, the response is: {"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 , which can be handled globally to return an error JSON.

Advanced Usage

Custom Executor

/**
 * Custom distributed lock 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

/**
 * Custom lock key generator
 */
@Component
public class CustomKeyBuilder extends DefaultLockKeyBuilder {
    public CustomKeyBuilder(BeanFactory beanFactory) {
        super(beanFactory);
    }
}

Custom Lock Failure Strategy

/**
 * Custom strategy when lock acquisition fails
 */
@Component
public class GrabLockFailureStrategy implements LockFailureStrategy {
    @Override
    public void onLockFailure(String key, Method method, Object[] arguments) {
        // custom handling logic
    }
}

The default failure 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
    }
}

The article concludes with a source reference and a promotional note for a backend‑focused technical community.