Redis的事务操作的命令与执行操作（代码）

本篇文章给大家带来的内容是关于Redis的事务操作的命令与执行操作（代码），有一定的参考价值，有需要的朋友可以参考一下，希望对你有所帮助。序本文主要研究一下redis的事务操作命令multi与exec命令行127.0.0.1:6379> multiOK127.0.0.1:6379> incr totalQUEUED127.0.0.1:6379> incr lenQUEUED127.0.0.1:6379> exec1) (integer) 22) (integer) 2127.0.0.1:6379> get total"2"127.0.0.1:6379> get len"2"lettuce实例@Testpublic void testMultiExec(){RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");StatefulRedisConnection<String, String> connection = client.connect();RedisCommands<String, String> syncCommands = connection.sync();syncCommands.set("hello","1");syncCommands.set("world","2");syncCommands.multi();syncCommands.incr("hello");syncCommands.incr("world");//DefaultTransactionResult[wasRolledBack=false,result=[1, 2, 1, 3, 1]]TransactionResult transactionResult = syncCommands.exec();System.out.println(transactionResult);System.out.println(syncCommands.get("hello"));System.out.println(syncCommands.get("world"));}部分执行命令行127.0.0.1:6379> multiOK127.0.0.1:6379> set a helloQUEUED127.0.0.1:6379> set b worldQUEUED127.0.0.1:6379> incr aQUEUED127.0.0.1:6379> set c partQUEUED127.0.0.1:6379> exec1) OK2) OK3) (error) ERR value is not an integer or out of range4) OK127.0.0.1:6379> get a"hello"127.0.0.1:6379> get b"world"127.0.0.1:6379> get c"part"lettuce实例@Testpublic void testMultiExecError(){RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");StatefulRedisConnection<String, String> connection = client.connect();RedisCommands<String, String> syncCommands = connection.sync();syncCommands.multi();syncCommands.set("a","hello");syncCommands.set("b","world");syncCommands.incr("a");syncCommands.set("c","part");//DefaultTransactionResult[wasRolledBack=false,result=[OK, OK, io.lettuce.core.RedisCommandExecutionException: ERR value is not an integer or out of range, OK, 1]]TransactionResult transactionResult = syncCommands.exec();System.out.println(transactionResult);System.out.println(syncCommands.get("a"));System.out.println(syncCommands.get("b"));System.out.println(syncCommands.get("c"));}multi与discard命令行127.0.0.1:6379> set sum 1OK127.0.0.1:6379> multiOK127.0.0.1:6379> incr sumQUEUED127.0.0.1:6379> discardOK127.0.0.1:6379> get sum"1"lettuce实例@Testpublic void testMultiDiscard(){RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");StatefulRedisConnection<String, String> connection = client.connect();RedisCommands<String, String> syncCommands = connection.sync();syncCommands.incr("key1");syncCommands.multi();syncCommands.incr("key1");//需要有multi才可以执行discard，成功返回OKString result = syncCommands.discard();System.out.println(result);System.out.println(syncCommands.get("key1"));}check and set@Testpublic void testWatch(){RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");StatefulRedisConnection<String, String> connection = client.connect();RedisCommands<String, String> syncCommands = connection.sync();String key = "key";syncCommands.watch(key);//another connectionStatefulRedisConnection<String, String> conn2 = client.connect();RedisCommands<String, String> syncCommands2 = conn2.sync();syncCommands2.set(key, "a");syncCommands.multi();syncCommands.append(key, "b");//DefaultTransactionResult [wasRolledBack=true, responses=0]TransactionResult transactionResult = syncCommands.exec();System.out.println(transactionResult);System.out.println(syncCommands.get(key));}小结reids提供multi exec/discard指令，类似open commit/rollback transaction，不过exec遇到类型操作等错误时不会滚，该成功执行的命令还是成功执行，该失败的还是失败

multi exec保证的是，只要exec命令有执行成功，则事务中一系列的命令都能执行，如果exec因为网络等问题，server端没有接收到，则事务中的一系列命令都不会被执行

discard需要在有调用multi的前提下才能使用，该命令会清空事务队列等待执行的命令

redis提供watch指令，可以配合multi exec来使用，可以实现类似数据库的乐观锁的机制，一旦watch的key被其他client有更新，则整个exec操作失败

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