[笔记迁移][Redis][8]Redis的Java客户端—Jedis

版权声明：Collected by Bro_Rabbit only for study https://blog.csdn.net/weixin_38240095/article/details/83420309

一、连通性测试

注意：连接前必须关闭Redis服务所在主机的Linux防火墙 [参照：https://www.cnblogs.com/moxiaoan/p/5683743.html]

//获取一个Redis客户端
Jedis jedisClient = new Jedis("192.168.109.191", 6379);
//正常连接将返回PONG，若未关闭防火墙则抛出超时异常
System.out.println(jedisClient.ping());

二、基本操作API参照之前的Shell命令

三、事务提交

1. 一般API

   //1.开启事务,注意区分Transaction类，不要导错
   Transaction tx=jedisClient.multi();
   //2.Transaction可调用大部分方法
   tx.set("k1","v111");
   tx.set("k2","v222");
   //3.提交执行事务
   tx.exec();
   // 放弃本次事务
   tx.discard();
   

2. 并发“锁机制”—watch与unwatch

   	public static  boolean txMethod(){
   	Jedis jedisClient = new Jedis("192.168.109.191",6379);
   	
   	int balance=0;
   	int debt=0;
   	int amtToSubtract=20;
   	
   	//1. 为balance加锁监视
   	jedisClient.watch("balance");
   	
   	balance=Integer.parseInt(jedisClient.get("balance"));
   	
   	
   	if(balance<amtToSubtract){
   		//2. 先行判断，若不满足直接解锁，返回失败
   		jedisClient.unwatch();
   		return false;
   	}else{
   		System.out.println("=====Transaction start=====");
   		//3. 满足后，开启事务修改，提交后解锁，返回成功
   		Transaction tx = jedisClient.multi();
   		tx.decrBy("balance", amtToSubtract);
   		tx.incrBy("debt", amtToSubtract);
   		tx.exec();
   		System.out.println("=====Transaction commit=====");
   		
   		balance=Integer.parseInt(jedisClient.get("balance"));
   		debt=Integer.parseInt(jedisClient.get("debt"));
   		System.out.println("=====balance====="+balance);
   		System.out.println("=====debt====="+debt);
   		
   		return true;
   	}
   }
   

四、主从复制

Jedis master = new Jedis("192.168.109.191",6379);
Jedis slave1 = new Jedis("192.168.109.191",6380);
Jedis slave2 = new Jedis("192.168.109.191",6381);
		 
slave1.slaveof("192.168.109.191", 6379);
slave2.slaveof("192.168.109.191", 6380);
		 
master.set("class", "1");
		 
System.out.println("slave1 get===>"+slave1.get("class"));