maven依赖

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.16.14</version>
</dependency>

 

帮助类 采用redis的setNX实现

• SETNX(SET If Not Exists)：当且仅当 Key 不存在时，则可以设置，否则不做任何动作。

 

package com.whq.test;import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;import java.util.concurrent.TimeUnit;@Component
@Slf4j
public class DistributedLockHelper {private final static long LOCK_EXPIRE = 30 * 1000L;//单个业务持有锁的时间30s，防止死锁private final static long LOCK_TRY_INTERVAL = 30L;//默认30ms尝试一次private final static long LOCK_TRY_TIMEOUT = 20 * 1000L;//默认尝试20s@Autowiredprivate StringRedisTemplate stringRedisTemplate;/*** 尝试获取全局锁** @param key 锁的名称* @return true 获取成功，false获取失败*/public boolean tryLock(String key) {return getLock(key, LOCK_TRY_TIMEOUT, LOCK_TRY_INTERVAL, LOCK_EXPIRE);}/*** 尝试获取全局锁** @param key    锁的名称* @param timeout 获取超时时间 单位ms* @return true 获取成功，false获取失败*/public boolean tryLock(String key, long timeout) {return getLock(key, timeout, LOCK_TRY_INTERVAL, LOCK_EXPIRE);}/*** 尝试获取全局锁** @param key        锁的名称* @param timeout     获取锁的超时时间* @param tryInterval 多少毫秒尝试获取一次* @return true 获取成功，false获取失败*/public boolean tryLock(String key, long timeout, long tryInterval) {return getLock(key, timeout, tryInterval, LOCK_EXPIRE);}/*** 尝试获取全局锁** @param key           锁的名称* @param timeout        获取锁的超时时间* @param tryInterval    多少毫秒尝试获取一次* @param lockExpireTime 锁的过期* @return true 获取成功，false获取失败*/public boolean tryLock(String key, long timeout, long tryInterval, long lockExpireTime) {return getLock(key, timeout, tryInterval, lockExpireTime);}/*** 操作redis获取全局锁** @param key           锁的名称* @param timeout        获取的超时时间* @param tryInterval    多少ms尝试一次* @param lockExpireTime 获取成功后锁的过期时间* @return true 获取成功，false获取失败*/public boolean getLock(String key, long timeout, long tryInterval, long lockExpireTime) {try {if (StringUtils.isEmpty(key)) {return false;}long startTime = System.currentTimeMillis();while(true){if (!stringRedisTemplate.hasKey(key)) {ValueOperations<String, String> ops = stringRedisTemplate.opsForValue();if(ops.setIfAbsent(key, "", lockExpireTime, TimeUnit.MILLISECONDS)) {return true;}} else {//存在锁log.debug("lock is exist!！！");}if (System.currentTimeMillis() - startTime > timeout) {//尝试超过了设定值之后直接跳出循环return false;}Thread.sleep(tryInterval);}} catch (InterruptedException e) {log.error(e.getMessage());return false;}}/*** 释放锁*/public void releaseLock(String key) {if (!StringUtils.isEmpty(key)) {stringRedisTemplate.delete(key);}}}

调用测试

 

@RestController
@SpringBootApplication
@Slf4j
public class TestApplication {public static void main(String[] args) {SpringApplication.run(TestApplication.class, args);}@Autowiredprivate DistributedLockHelper distributedLockHandler;@RequestMapping("lock")public String lock(){String key="testlock";log.info("准备获取锁");if(distributedLockHandler.tryLock(key)){try {//为了演示锁的效果，这里睡眠5000毫秒log.info("已经获取到锁");Thread.sleep(5000);}catch (Exception e){e.printStackTrace();}distributedLockHandler.releaseLock(key);log.info("锁已释放");}return "hello world!";}
}

配置application.yml

server:port: 18081spring:redis:host: 10.0.197.189port: 6379

 

注意：测试时要采用两个浏览器，或者一个用ip、一个用localhost访问，否则浏览器会同时只能进行一个请求。

测试输出日志

 

2019-07-23 14:42:52 1997495 [http-nio-18081-exec-1] INFO  com.whq.test.TestApplication - 准备获取锁 
2019-07-23 14:42:52 1997507 [http-nio-18081-exec-1] INFO  com.whq.test.TestApplication - 已经获取到锁 
2019-07-23 14:42:53 1998452 [http-nio-18081-exec-3] INFO  com.whq.test.TestApplication - 准备获取锁 
2019-07-23 14:42:57 2002510 [http-nio-18081-exec-1] INFO  com.whq.test.TestApplication - 锁已释放 
2019-07-23 14:42:57 2002530 [http-nio-18081-exec-3] INFO  com.whq.test.TestApplication - 已经获取到锁 
2019-07-23 14:43:02 2007535 [http-nio-18081-exec-3] INFO  com.whq.test.TestApplication - 锁已释放