Redis处理⾼并发 实现分布式锁

Redisson

Redisson是架设在Redis基础上的⼀个Java驻内存数据⽹格（In-Memory Data Grid）。 Redisson在基于NIO的Netty框架上，充分的利⽤了Redis键值数据库提供的⼀系列优势，在Java实⽤⼯具包中常⽤ 接⼝的基础上，为使⽤者提供了⼀系列具有分布式特性的常⽤⼯具类。使得原本作为协调单机多线程并发程序的⼯ 具包获得了协调分布式多机多线程并发系统的能⼒，⼤⼤降低了设计和研发⼤规模分布式系统的难度。同时结合各 富特⾊的分布式服务，更进⼀步简化了分布式环境中程序相互之间的协作。

Redisson使⽤

1.引⼊分布式锁的⼯具类 redisson 依赖。

<!-- 实现分布式锁的工具类 -->
<dependency>
  <groupId>org.redisson</groupId>
  <artifactId>redisson</artifactId>
  <version>3.17.7</version>
</dependency>
<!-- Spring操作Redis的工具类 -->
<dependency>
  <groupId>org.springframework.data</groupId>
  <artifactId>spring-data-redis</artifactId>
  <version>2.3.2.RELEASE</version>
</dependency>
<!-- Redis客户端 -->
<dependency>
  <groupId>redis.clients</groupId>
  <artifactId>jedis</artifactId>
  <version>3.9.0</version>
</dependency>
<!-- JSON解析工具 -->
<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.13.4</version>
</dependency>

package com.example.demo.controller;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.concurrent.TimeUnit;
@RestController
public class SecKillController {
 @Autowired
 private RedissonClient redisson;
 @Autowired
 private StringRedisTemplate stringRedisTemplate;
 @RequestMapping("seckill")
 public synchronized String secKill() {
 // 1.获取锁对象
 RLock redissonLock = redisson.getLock("phone");
 // 2.加锁(设置锁的过期时间为30秒)
 // redissonLock.lock();
 redissonLock.lock(30, TimeUnit.SECONDS);
 int phoneCount = 0;
  try {
   phoneCount =
           Integer.parseInt(stringRedisTemplate.opsForValue().get("phone_count"));
   if (phoneCount > 0) {
    phoneCount--;
    stringRedisTemplate.opsForValue().set("phone_count",
            String.valueOf(phoneCount));
    System.out.println("库存-1后，库存剩余：" + phoneCount);
   } else {
    System.out.println("库存不⾜");
   }
  } catch (NumberFormatException e) {
   e.printStackTrace();
  } finally {
   // 3.释放锁
   redissonLock.unlock();
  }
  return "当前库存：" + phoneCount;
 }
}

在 com.yx.config 包下创建 RedissonConfig 配置类，初始化 RedissonClient 客户端。

以下提供了4种方式配置

package com;

import org.redisson.Redisson;
import org.redisson.api.RedissonClient;
import org.redisson.config.Config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class RedissonConfig {
    /** Redis单机模式 */
    @Bean
    public RedissonClient singletonModeRedisson() {
        Config config = new Config();
        // 使⽤"redis://"来启⽤SSL连接                                   //使用的是哪个数据库
     config.useSingleServer().setAddress("redis://192.168.48.67:6379").setDatabase(0);
        return Redisson.create(config);
    }
/** Redis集群模式 */
 /*
 @Bean
 public RedissonClient clusterModeRedisson() {
 Config config = new Config();
 config.useClusterServers()
 .setScanInterval(2000) // 群集状态扫描间隔（毫秒）
 .addNodeAddress("redis://192.168.230.131:6379",
"redis://192.168.230.132:6379", "redis://192.168.230.133:6379");
 return Redisson.create(config);
 }
 */
/** Redis哨兵模式 */

// @Bean
// public RedissonClient sentinelModeRedisson() {
// Config config = new Config();
// config.useSentinelServers()
// .setMasterName("myMaster").addSentinelAddress("redis://192.168.230.131:6379",
//"redis://192.168.230.132:6379", "redis://192.168.230.133:6379");
// return Redisson.create(config);
// }

    /** Redis主从模式 */

// @Bean
// public RedissonClient masterSlaveModeRedisson() {
// Config config = new Config();
// config.useMasterSlaveServers()
// // 主服务器IP
// .setMasterAddress("redis://192.168.230.131:6379")
// // 从服务器IP
// .addSlaveAddress("redis://192.168.230.132:6379",
//"redis://192.168.230.133:6379");
// return Redisson.create(config);
// }

}

在maven环境中还要如下配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation=" http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd">
<!--    包扫面-->
    <context:component-scan base-package="com"></context:component-scan>
<!--连接工厂-->
    <bean id="connectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">
    <property name="hostName" value="192.168.48.67"></property>
    <property name="port" value="6379"></property>
   </bean>
<!--Redis操作模板类-->
    <bean id="stringRedisTemplate"
          class="org.springframework.data.redis.core.StringRedisTemplate">
        <property name="connectionFactory" ref="connectionFactory"/>
    </bean>

</beans>

 在web.xml中进行如下配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

  <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:/Spring/Spring.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!-- 处理中文乱码的问题 -->
  <filter>
    <filter-name>encodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>