Redis的SETNX命令的简单分布式锁实现的Java示例
首先,确保你已经引入了Jedis这个Java Redis客户端库。你可以通过Maven或Gradle来添加依赖。
1、Maven依赖
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>3.7.0</version>
</dependency>
2、Java代码示例
import redis.clients.jedis.Jedis;
import java.util.UUID;
import java.util.concurrent.TimeUnit;
public class RedisDistributedLock {
private static final String LOCK_SUCCESS = "OK";
private static final String SET_IF_NOT_EXIST = "NX";
private static final String SET_WITH_EXPIRE_TIME = "PX";
private static final Long RELEASE_SUCCESS = 1L;
/**
* 尝试获取分布式锁
* @param jedis Redis客户端
* @param lockKey 锁
* @param requestId 请求标识
* @param expireTime 超期时间
* @return 是否获取成功
*/
public static boolean tryGetDistributedLock(Jedis jedis, String lockKey, String requestId, int expireTime) {
String result = jedis.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_TIME, expireTime);
return LOCK_SUCCESS.equals(result);
}
/**
* 释放分布式锁
* @param jedis Redis客户端
* @param lockKey 锁
* @param requestId 请求标识
* @return 是否释放成功
*/
public static boolean releaseDistributedLock(Jedis jedis, String lockKey, String requestId) {
String script = "if redis.call('get', KEYS[1]) == ARGV[1] then " +
"return redis.call('del', KEYS[1]) " +
"else " +
"return 0 " +
"end";
Object result = jedis.eval(script, Collections.singletonList(lockKey), Collections.singletonList(requestId));
return RELEASE_SUCCESS.equals(result);
}
public static void main(String[] args) {
Jedis jedis = new Jedis("localhost", 6379);
String lockKey = "myLock";
String requestId = UUID.randomUUID().toString();
int expireTime = 10 * 1000;
try {
if (tryGetDistributedLock(jedis, lockKey, requestId, expireTime)) {
try {
// 获取到锁,执行业务逻辑
System.out.println("执行业务逻辑...");
TimeUnit.SECONDS.sleep(5);
} finally {
releaseDistributedLock(jedis, lockKey, requestId);
}
} else {
// 没有获取到锁,执行其他逻辑
System.out.println("未获取到锁,执行其他逻辑...");
}
} finally {
if (jedis != null) {
jedis.close();
}
}
}
}
上述代码中,tryGetDistributedLock方法用于尝试获取分布式锁。它使用Redis的SET命令来实现,并通过NX和PX选项来确保只有在锁不存在时设置锁,并设置锁的过期时间。
releaseDistributedLock方法用于释放分布式锁,它使用Redis的Lua脚本来确保只有锁的持有者才能释放锁。