我们知道现在微服务很流行,为此,许多中小型企业都将自己以前的框架加以改造,其中以SpringCloud为最多,但是SpringCloud如果要加定时任务的话,在单台服务器上很好支持,但是涉及到集群服务(多台服务的话)就要用到分布式锁了,最简单的方案是用Redis,好了废话不多说,直接上代码.
第一步:在配置文件application.properties中加入Redis的相关配置:
#Redis配置 # REDIS (RedisProperties) # Redis数据库索引(默认为0) spring.redis.database=0 # Redis服务器地址 spring.redis.host=localhost # Redis服务器连接端口 spring.redis.port=6379 # Redis服务器连接密码(默认为空) spring.redis.password=
第二步:添加jar包依赖,这里以maven为例,pom.xml中加入
org.springframework.boot spring-boot-starter-data-redis
第三部:redis工具类的写法
1):新建Lock.java实体类
package com.great.springboot2.distributed; /** * 全局锁,包括锁的名称 Created by zuoguobin on 2017/4/1. */ public class Lock { private String name; private String value; public Lock(String name, String value) { this.name = name; this.value = value; } public String getName() { return name; } public String getValue() { return value; } }
2):新建DistributedLockHandler.java分布式锁工具类,此时注意:@Component的写法,目的是为了注入值
package com.great.springboot2.distributed; import org.slf4j.Logger; import org.slf4j.LoggerFactory; 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; /** * Created by zuoguobin on 2017/4/1. */ @Component public class DistributedLockHandler { private static final Logger logger = LoggerFactory.getLogger(DistributedLockHandler.class); 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 @Autowired private StringRedisTemplate template; /** * 尝试获取全局锁 * * @param lock * 锁的名称 * @return true 获取成功,false获取失败 */ public boolean tryLock(Lock lock) { return getLock(lock, LOCK_TRY_TIMEOUT, LOCK_TRY_INTERVAL, LOCK_EXPIRE); } /** * 尝试获取全局锁 * * @param lock * 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(Lock lock, long timeout) { return getLock(lock, timeout, LOCK_TRY_INTERVAL, LOCK_EXPIRE); } /** * 尝试获取全局锁 * * @param lock * 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(Lock lock, long timeout, long tryInterval) { return getLock(lock, timeout, tryInterval, LOCK_EXPIRE); } /** * 尝试获取全局锁 * * @param lock * 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(Lock lock, long timeout, long tryInterval, long lockExpireTime) { return getLock(lock, timeout, tryInterval, lockExpireTime); } /** * 操作redis获取全局锁 * * @param lock * 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(Lock lock, long timeout, long tryInterval, long lockExpireTime) { try { if (StringUtils.isEmpty(lock.getName()) || StringUtils.isEmpty(lock.getValue())) { return false; } long startTime = System.currentTimeMillis(); do { if (!template.hasKey(lock.getName())) { ValueOperationsops = template.opsForValue(); ops.set(lock.getName(), lock.getValue(), lockExpireTime, TimeUnit.MILLISECONDS); return true; } else {// 存在锁 logger.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); } while (template.hasKey(lock.getName())); } catch (InterruptedException e) { logger.error(e.getMessage()); return false; } return false; } /** * 释放锁 */ public void releaseLock(Lock lock) { if (!StringUtils.isEmpty(lock.getName())) { template.delete(lock.getName()); } } }
第四步:添加定时任务,这里是一秒执行一次,注意@Component要加上让系统扫描到,停用定时任务就把它拿掉!
package com.great.springboot2.distributed; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.redis.core.StringRedisTemplate; import org.springframework.scheduling.annotation.Scheduled; import org.springframework.stereotype.Component; import java.text.SimpleDateFormat; @Component public class MyScheduler { private final Logger logger = LoggerFactory.getLogger(this.getClass()); @Autowired private StringRedisTemplate template; @Autowired DistributedLockHandler distributedLockHandler; @Scheduled(fixedRate = 6000) public void task() throws InterruptedException { Lock lock=new Lock("testlock","lockvalue"); if(distributedLockHandler.tryLock(lock)){ //Thread.sleep(40000); SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); logger.info("everOne22222 start....。。。。。。。。。。。startTime="+ df.format(System.currentTimeMillis())); System.out.println("template --"+template); System.out.println("distributedLockHandler --"+distributedLockHandler); try{ Thread.sleep(10000); }catch (Exception e){ } //statusTask.healthCheck(); // int i=10/0; logger.info("everOne222222 end...。。。。。。。。。。。。 endTime="+df.format(System.currentTimeMillis())); distributedLockHandler.releaseLock(lock); } } }
第五步:在应用程序启动类加上注解@EnableScheduling,这个是要加上的,对计划任务的支持
package com.great.springboot2; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.scheduling.annotation.EnableScheduling; @EnableScheduling @SpringBootApplication public class Springboot2Application { public static void main(String[] args) { SpringApplication.run(Springboot2Application.class, args); } }
第六步,分别用两个不同的端口启动两个Springboot服务
正常情况下,同一时间只有一个服务的定时任务在运行中!!?
说明,但是当多个服务的定时任务执行很快或者2个服务的启动时间非常接近的时候,会存在锁判断不准确的情况,两个服务中的定时任务同时都在运行!
因此对第三步的DistributedLockHandler.java分布式锁工具类做了一点修改:
package com.great.springboot2.distributed; import org.slf4j.Logger; import org.slf4j.LoggerFactory; 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; /** * Created by zuoguobin on 2017/4/1. */ @Component public class DistributedLockHandler { private static final Logger logger = LoggerFactory.getLogger(DistributedLockHandler.class); private final static long LOCK_EXPIRE = 30 * 1000L;// 单个业务持有锁的时间30s,防止死锁 @Autowired private StringRedisTemplate template; /** * 尝试获取全局锁 * * @param lock * 锁的名称 * @return true 获取成功,false获取失败 */ public boolean tryLock(Lock lock) { return getLock(lock, LOCK_EXPIRE); } /** * 尝试获取全局锁 * * @param lock * 锁的名称 * @param lockExpireTime * 锁的过期 * @return true 获取成功,false获取失败 */ public boolean tryLock(Lock lock, long lockExpireTime) { return getLock(lock, lockExpireTime); } /** * 操作redis获取全局锁 * * @param lock * 锁的名称 * @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(Lock lock, long lockExpireTime) { try { if (StringUtils.isEmpty(lock.getName()) || StringUtils.isEmpty(lock.getValue())) { return false; } long startTime = System.currentTimeMillis(); if (!template.hasKey(lock.getName())) { ValueOperationsops = template.opsForValue(); ops.set(lock.getName(), lock.getValue(), lockExpireTime, TimeUnit.MILLISECONDS); return true; } else {// 存在锁 logger.error("lock is exist!!!"); return false; } } catch (Exception e) { logger.error(e.getMessage()); return false; } } /** * 释放锁 */ public void releaseLock(Lock lock) { if (!StringUtils.isEmpty(lock.getName())) { template.delete(lock.getName()); } } }
最终的执行结果:
A服务器日志:
2018-07-18 15:05:40.299 INFO 93616 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne22222 start....。。。。。。。。。。。startTime=2018-07-18 15:05:40 2018-07-18 15:06:11.301 INFO 93616 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne222222 end...。。。。。。。。。。。。 endTime=2018-07-18 15:06:11 2018-07-18 15:06:40.301 INFO 93616 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne22222 start....。。。。。。。。。。。startTime=2018-07-18 15:06:40 2018-07-18 15:07:11.318 INFO 93616 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne222222 end...。。。。。。。。。。。。 endTime=2018-07-18 15:07:11 2018-07-18 15:07:40.299 INFO 93616 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne22222 start....。。。。。。。。。。。startTime=2018-07-18 15:07:40 2018-07-18 15:08:11.331 INFO 93616 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne222222 end...。。。。。。。。。。。。 endTime=2018-07-18 15:08:11 2018-07-18 15:08:40.335 ERROR 93616 --- [pool-1-thread-1] c.g.s.d.DistributedLockHandler : lock is exist!!! 2018-07-18 15:09:40.299 ERROR 93616 --- [pool-1-thread-1] c.g.s.d.DistributedLockHandler : lock is exist!!! 2018-07-18 15:10:40.314 ERROR 93616 --- [pool-1-thread-1] c.g.s.d.DistributedLockHandler : lock is exist!!!
B服务器日志:
2018-07-18 15:08:11.602 INFO 90116 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne22222 start....。。。。。。。。。。。startTime=2018-07-18 15:08:11 2018-07-18 15:08:42.604 INFO 90116 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne222222 end...。。。。。。。。。。。。 endTime=2018-07-18 15:08:42 2018-07-18 15:09:11.000 INFO 90116 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne22222 start....。。。。。。。。。。。startTime=2018-07-18 15:09:11 2018-07-18 15:09:42.002 INFO 90116 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne222222 end...。。。。。。。。。。。。 endTime=2018-07-18 15:09:42 2018-07-18 15:10:11.001 INFO 90116 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne22222 start....。。。。。。。。。。。startTime=2018-07-18 15:10:11 2018-07-18 15:10:42.003 INFO 90116 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne222222 end...。。。。。。。。。。。。 endTime=2018-07-18 15:10:42 2018-07-18 15:11:11.000 INFO 90116 --- [pool-1-thread-1] c.g.springboot2.distributed.MyScheduler : everOne22222 start....。。。。。。。。。。。startTime=2018-07-18 15:11:11