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Redis 是最流行的 NoSQL 数据库解决方案之一#xff0c;而 Java 是世界上最流行#xff08;注意#xff0c;我没有说“最好”#xff09;的编程语言之一。虽然两者看起来很自然地在一起“工作”#xff0c;但是要知道#xff0c;Redis 其实并没有对 Java…1.Redisson简介
Redis 是最流行的 NoSQL 数据库解决方案之一而 Java 是世界上最流行注意我没有说“最好”的编程语言之一。虽然两者看起来很自然地在一起“工作”但是要知道Redis 其实并没有对 Java 提供原生支持。
相反作为 Java 开发人员我们若想在程序中集成 Redis必须使用 Redis 的第三方库。而 Redisson 就是用于在 Java 程序中操作 Redis 的库它使得我们可以在程序中轻松地使用 Redis。Redisson 在 java.util 中常用接口的基础上为我们提供了一系列具有分布式特性的工具类。 Redisson底层采用的是Netty 框架。支持Redis 2.8以上版本支持Java1.6以上版本。 2.Redisson实现分布式锁的步骤
2.1.引入依赖
引入重要的两个依赖一个是spring-boot-starter-data-redis一个是redisson
dependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-data-redis/artifactId
/dependencydependencygroupIdorg.redisson/groupIdartifactIdredisson/artifactIdversion3.7.5/version
/dependency2.2.application.properties
# Redis服务器地址默认session使用
spring.redis.host127.0.0.1
# Redis服务器连接密码默认为空
# spring.redis.password
# Redis服务器连接端口
spring.redis.port63792.3.定义Loker
接口编程的思想还是要保持的。我们定义一个Loker接口用于分布式锁的一些操作
package com.bruceliu.lock;/*** BelongsProject: RedissonLock* BelongsPackage: com.bruceliu.lock* Author: bruceliu* QQ:1241488705* CreateTime: 2020-05-08 10:20* Description: 锁接口*/
import java.util.concurrent.TimeUnit;public interface Locker {/*** 获取锁如果锁不可用则当前线程处于休眠状态直到获得锁为止。** param lockKey*/void lock(String lockKey);/*** 释放锁** param lockKey*/void unlock(String lockKey);/*** 获取锁,如果锁不可用则当前线程处于休眠状态直到获得锁为止。如果获取到锁后执行结束后解锁或达到超时时间后会自动释放锁** param lockKey* param timeout*/void lock(String lockKey, int timeout);/*** 获取锁,如果锁不可用则当前线程处于休眠状态直到获得锁为止。如果获取到锁后执行结束后解锁或达到超时时间后会自动释放锁** param lockKey* param unit* param timeout*/void lock(String lockKey, TimeUnit unit, int timeout);/*** 尝试获取锁获取到立即返回true,未获取到立即返回false** param lockKey* return*/boolean tryLock(String lockKey);/*** 尝试获取锁在等待时间内获取到锁则返回true,否则返回false,如果获取到锁则要么执行完后程序释放锁* 要么在给定的超时时间leaseTime后释放锁** param lockKey* param waitTime* param leaseTime* param unit* return*/boolean tryLock(String lockKey, long waitTime, long leaseTime, TimeUnit unit)throws InterruptedException;/*** 锁是否被任意一个线程锁持有** param lockKey* return*/boolean isLocked(String lockKey);
}
有了Locker接口我们再添加一个基于Redisson的实现类RedissonLocker实现Locker中的方法
package com.bruceliu.lock;/*** BelongsProject: RedissonLock* BelongsPackage: com.bruceliu.lock* Author: bruceliu* QQ:1241488705* CreateTime: 2020-05-08 10:20* Description: 基于Redisson的分布式锁*/
import java.util.concurrent.TimeUnit;import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;public class RedissonLocker implements Locker {private RedissonClient redissonClient;public RedissonLocker(RedissonClient redissonClient) {super();this.redissonClient redissonClient;}Overridepublic void lock(String lockKey) {RLock lock redissonClient.getLock(lockKey);lock.lock();}Overridepublic void unlock(String lockKey) {RLock lock redissonClient.getLock(lockKey);lock.unlock();}Overridepublic void lock(String lockKey, int leaseTime) {RLock lock redissonClient.getLock(lockKey);lock.lock(leaseTime, TimeUnit.SECONDS);}Overridepublic void lock(String lockKey, TimeUnit unit, int timeout) {RLock lock redissonClient.getLock(lockKey);lock.lock(timeout, unit);}public void setRedissonClient(RedissonClient redissonClient) {this.redissonClient redissonClient;}Overridepublic boolean tryLock(String lockKey) {RLock lock redissonClient.getLock(lockKey);return lock.tryLock();}Overridepublic boolean tryLock(String lockKey, long waitTime, long leaseTime,TimeUnit unit) throws InterruptedException{RLock lock redissonClient.getLock(lockKey);return lock.tryLock(waitTime, leaseTime, unit);}Overridepublic boolean isLocked(String lockKey) {RLock lock redissonClient.getLock(lockKey);return lock.isLocked();}}
2.4.定义工具类
有了Locker和实现类RedissonLocker我们总不能一直去创建RedissonLocker对象或者不断的在每个要使用到分布式锁的地方都注入RedissonLocker的对象所以我们定义一个工具类LockUtil到时候想哪里使用就直接使用工具类的静态方法就行了
package com.bruceliu.utils;/*** BelongsProject: RedissonLock* BelongsPackage: com.bruceliu.utils* Author: bruceliu* QQ:1241488705* CreateTime: 2020-05-08 10:21* Description: TODO*/
import com.bruceliu.lock.Locker;import java.util.concurrent.TimeUnit;/*** redis分布式锁工具类**/
public final class LockUtil {private static Locker locker;/*** 设置工具类使用的locker* param locker*/public static void setLocker(Locker locker) {LockUtil.locker locker;}/*** 获取锁* param lockKey*/public static void lock(String lockKey) {locker.lock(lockKey);}/*** 释放锁* param lockKey*/public static void unlock(String lockKey) {locker.unlock(lockKey);}/*** 获取锁超时释放* param lockKey* param timeout*/public static void lock(String lockKey, int timeout) {locker.lock(lockKey, timeout);}/*** 获取锁超时释放指定时间单位* param lockKey* param unit* param timeout*/public static void lock(String lockKey, TimeUnit unit, int timeout) {locker.lock(lockKey, unit, timeout);}/*** 尝试获取锁获取到立即返回true,获取失败立即返回false* param lockKey* return*/public static boolean tryLock(String lockKey) {return locker.tryLock(lockKey);}/*** 尝试获取锁在给定的waitTime时间内尝试获取到返回true,获取失败返回false,获取到后再给定的leaseTime时间超时释放* param lockKey* param waitTime* param leaseTime* param unit* return* throws InterruptedException*/public static boolean tryLock(String lockKey, long waitTime, long leaseTime,TimeUnit unit) throws InterruptedException {return locker.tryLock(lockKey, waitTime, leaseTime, unit);}/*** 锁释放被任意一个线程持有* param lockKey* return*/public static boolean isLocked(String lockKey) {return locker.isLocked(lockKey);}
}2.5.Redisson的配置类
现在我们开始配置吧创建一个redisson的配置类RedissonConfig内容如下
package com.bruceliu.config;import java.io.IOException;import com.bruceliu.lock.RedissonLocker;
import com.bruceliu.utils.LockUtil;
import org.redisson.Redisson;
import org.redisson.api.RedissonClient;
import org.redisson.config.Config;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;/*** BelongsProject: RedissonLock* BelongsPackage: com.bruceliu.config* Author: bruceliu* QQ:1241488705* CreateTime: 2020-05-08 10:22* Description: TODO*/
Configuration
public class RedissonConfig {Value(${spring.redis.host})private String host;Value(${spring.redis.port})private String port;//Value(${spring.redis.password})//private String password;/*** RedissonClient,单机模式* return* throws IOException*/Bean(destroyMethod shutdown)public RedissonClient redisson() throws IOException {Config config new Config();//config.useSingleServer().setAddress(redis:// host : port).setPassword(password);config.useSingleServer().setAddress(redis:// host : port);return Redisson.create(config);}Beanpublic RedissonLocker redissonLocker(RedissonClient redissonClient){RedissonLocker locker new RedissonLocker(redissonClient);//设置LockUtil的锁处理对象LockUtil.setLocker(locker);return locker;}
}
2.6.Redisson分布式锁业务类
package com.bruceliu.service;import com.bruceliu.utils.LockUtil;import java.util.concurrent.TimeUnit;/*** BelongsProject: RedissonLock* BelongsPackage: com.bruceliu.service* Author: bruceliu* QQ:1241488705* CreateTime: 2020-05-08 10:26* Description: TODO*/
public class SkillService {int n 500;public void seckill() {//加锁LockUtil.lock(resource, TimeUnit.SECONDS,5000);try {System.out.println(Thread.currentThread().getName() 获得了锁);Thread.sleep(3000);System.out.println(--n);} catch (Exception e) {//异常处理}finally{//释放锁LockUtil.unlock(resource);System.out.println(Thread.currentThread().getName() 释放了锁);}}
}
2.7.Redisson分布式锁测试
package com.bruceliu.test;import com.bruceliu.App;
import com.bruceliu.service.SkillService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;/*** BelongsProject: RedissonLock* BelongsPackage: com.bruceliu.test* Author: bruceliu* QQ:1241488705* CreateTime: 2020-05-08 10:29* Description: TODO*/
RunWith(SpringRunner.class)
SpringBootTest(classes App.class)
public class TestLock {Testpublic void testLock() throws Exception{SkillService service new SkillService();for (int i 0; i 10; i) {ThreadA threadA new ThreadA(service);threadA.setName(ThreadNameA-i);threadA.start();}Thread.sleep(50000);}}class ThreadA extends Thread {private SkillService skillService;public ThreadA(SkillService skillService) {this.skillService skillService;}Overridepublic void run() {skillService.seckill();}
}
运行结果:
注释文中加锁代码
public void seckill() {//加锁//LockUtil.lock(resource, TimeUnit.SECONDS,5000);try {System.out.println(Thread.currentThread().getName() 获得了锁);Thread.sleep(3000);System.out.println(--n);} catch (Exception e) {//异常处理}finally{//释放锁//LockUtil.unlock(resource);System.out.println(Thread.currentThread().getName() 释放了锁);}
}运行结果 可以看到存在并发的问题
