本文今天主要是Redis的事务的使用,以及redis对应的Java实现该怎么用。因为篇幅问题,我这里写了一个测试类,引入 RedisTemplate对象,后面例子里就不一一引入了。大家理解就行,如果大家还不知道如何通过Spring Boot 整合redis则可以查看我之前的文章:SpringBoot整合redis(redis支持单节点和集群)
package com.alian.datastruct;import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import java.util.List;
import java.util.concurrent.TimeUnit;@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class RedisTransactionTest {@Autowiredprivate RedisTemplate redisTemplate;
}
一个事务从开始到执行会经历以下三个阶段:
MULTI
命令1
命令2
...
命令n
EXEC
命令操作
127.0.0.1:6379> multi
OK
127.0.0.1:6379> set name alian
QUEUED
127.0.0.1:6379> set age 28
QUEUED
127.0.0.1:6379> set sex nan
QUEUED
127.0.0.1:6379> exec
1) OK
2) OK
3) OK
127.0.0.1:6379> get name
"alian"
127.0.0.1:6379> get age
"28"
127.0.0.1:6379> get sex
"nan"
Java操作
@Testpublic void startTransaction() {redisTemplate.delete(Arrays.asList("name", "age", "sex"));redisTemplate.execute(new SessionCallback>() {public List
事务提交后的姓名:alian
事务提交后的年龄:28
事务提交后的性别:男
MULTI
命令1
命令2
...
命令n
DISCARD
命令操作
127.0.0.1:6379> multi
OK
127.0.0.1:6379> set orderId 202212230102
QUEUED
127.0.0.1:6379> set title BirthdayCake
QUEUED
127.0.0.1:6379> set price 168
QUEUED
127.0.0.1:6379> discard
OK
127.0.0.1:6379> get orderId
(nil)
127.0.0.1:6379> get title
(nil)
127.0.0.1:6379> get price
(nil)
Java操作
@Testpublic void cancelTransaction() {redisTemplate.delete(Arrays.asList("orderId", "title", "price"));redisTemplate.execute(new SessionCallback>() {public List
事务取消后的姓名:null
事务取消后的年龄:null
事务取消后的性别:null
从这里可以看到,取消事务后,命令都未执行。
一般是命令写错了或者命令不存在导致,比如不存在的命令
命令操作
127.0.0.1:6379> multi
OK
127.0.0.1:6379> set name alian
QUEUED
127.0.0.1:6379> set age 28
QUEUED
127.0.0.1:6379> setget sex man ##故意写错命令
(error) ERR unknown command `setget`, with args beginning with: `sex`, `man`,
127.0.0.1:6379> set hobby write
QUEUED
127.0.0.1:6379> exec
(error) EXECABORT Transaction discarded because of previous errors.
127.0.0.1:6379> get name
(nil)
127.0.0.1:6379> get age
(nil)
127.0.0.1:6379> get hobby
(nil)
编译时异常后面的命令都执行失败
一般是类型错误了,比如没有按指定类型获取值,或者是给非数字字符做自增等
命令操作
127.0.0.1:6379> multi
OK
127.0.0.1:6379> set title basketball
QUEUED
127.0.0.1:6379> set price 239
QUEUED
127.0.0.1:6379> hgetall title ##title的类型是string不是hash
QUEUED
127.0.0.1:6379> set address shenzhen
QUEUED
127.0.0.1:6379> exec
1) OK
2) OK
3) (error) WRONGTYPE Operation against a key holding the wrong kind of value
4) OK
127.0.0.1:6379> get title
"basketball"
127.0.0.1:6379> get price
"239"
127.0.0.1:6379> get address
"shenzhen"
运行时异常并不影响后面命令的执行。
Redis单条命令是原子性的,但是Redis事务是不保证原子性的,会按照顺序一条条执行
用一个场景来模拟乐观锁。
终端1
127.0.0.1:6379> set money 0
OK
127.0.0.1:6379> set num 10
OK
127.0.0.1:6379> watch money
OK
127.0.0.1:6379> multi
OK
127.0.0.1:6379> incrby money 100
QUEUED
127.0.0.1:6379> decrby num 1
QUEUED
终端2
127.0.0.1:6379> get money
"0"
127.0.0.1:6379> incrby money 50
(integer) 50
终端1
127.0.0.1:6379> exec
(nil)
127.0.0.1:6379> get money
"50"
127.0.0.1:6379> get num
"10"
正常操作
127.0.0.1:6379> unwatch
OK
127.0.0.1:6379> watch money
OK
127.0.0.1:6379> multi
OK
127.0.0.1:6379> incrby money 100
QUEUED
127.0.0.1:6379> decrby num 1
QUEUED
127.0.0.1:6379> exec
1) (integer) 150
2) (integer) 9
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