Redis实战之Lettuce使用技巧详解，真香！

一、真香摘要

Lettuce 是实e使 Redis 的一款高级 Java 客户端，与 Jedis 并列成为最热门的用技客户端之一，目前已成为 SpringBoot 2.0 版本默认的巧详 redis 客户端。

相比老牌 Jedis，真香Lettuce 属于后起之秀，实e使不仅功能丰富，用技而且提供了很多新的巧详功能特性，比如异步操作、真香响应式编程等等，实e使同时还解决了 Jedis 中线程不安全的用技问题。

废话不多说了，巧详如何使用呢？真香请看下文！

二、实e使Lettuce

2.1、用技基本使用

首先，创建一个 maven 项目，引入​​lettuce-core​​包，就可以使用了。

复制<dependency> <groupId>io.lettuce</groupId> <artifactId>lettuce-core</artifactId> <version>5.3.1.RELEASE</version></dependency>1.2.3.4.5.

使用 lettuce 连接 redis，测试是否能正常联通！

复制public class LettuceMain { public static void main(String[] args){ RedisURI redisUri = RedisURI.builder() .withHost("127.0.0.1") .withPort(6379) .withPassword("111111") .withTimeout(Duration.of(10, ChronoUnit.SECONDS)) .build(); RedisClient redisClient = RedisClient.create(redisUri); StatefulRedisConnection<String, String> connection = redisClient.connect(); RedisCommands<String, String> commands = connection.sync(); System.out.println(commands.ping()); connection.close(); redisClient.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17. 2.2、同步操作

基本上只要是 Jedis 支持的同步命令操作，Lettuce 都支持。

下面，免费源码下载我们以同步操作字符串为例，Lettuce 的 api 操作如下！

复制public class LettuceSyncMain { public static void main(String[] args){ RedisURI redisUri = RedisURI.builder() .withHost("127.0.0.1").withPort(6379).withPassword("111111") .withTimeout(Duration.of(10, ChronoUnit.SECONDS)) .build(); RedisClient redisClient = RedisClient.create(redisUri); StatefulRedisConnection<String, String> connection = redisClient.connect(); //

获取同步操作命令工具

RedisCommands<String, String> commands = connection.sync(); System.out.println("清空数据："+commands.flushdb()); System.out.println("判断某个键是否存在："+commands.exists("username")); System.out.println("新增<username,xmr>的键值对："+commands.set("username", "xmr")); System.out.println("新增<password,password>的键值对："+commands.set("password", "123")); System.out.println("获取<password>键的值："+commands.get("password")); System.out.println("系统中所有的键如下：" + commands.keys("*")); System.out.println("删除键password:"+commands.del("password")); System.out.println("判断键password是否存在："+commands.exists("password")); System.out.println("设置键username的过期时间为5s:"+commands.expire("username", 5L)); System.out.println("查看键username的剩余生存时间："+commands.ttl("username")); System.out.println("移除键username的生存时间："+commands.persist("username")); System.out.println("查看键username的剩余生存时间："+commands.ttl("username")); System.out.println("查看键username所存储的值的类型："+commands.type("username")); connection.close(); redisClient.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30. 2.3、异步操作

除此之外，Lettuce 还支持异步操作，将上面的操作改成异步处理，结果如下！

复制public class LettuceASyncMain { public static void main(String[] args) throws Exception { RedisURI redisUri = RedisURI.builder() .withHost("127.0.0.1").withPort(6379).withPassword("111111") .withTimeout(Duration.of(10, ChronoUnit.SECONDS)) .build(); RedisClient redisClient = RedisClient.create(redisUri); StatefulRedisConnection<String, String> connection = redisClient.connect(); //

获取异步操作命令工具

RedisAsyncCommands<String, String> commands = connection.async(); System.out.println("清空数据："+commands.flushdb().get()); System.out.println("判断某个键是否存在："+commands.exists("username").get()); System.out.println("新增<username,xmr>的键值对："+commands.set("username", "xmr").get()); System.out.println("新增<password,password>的键值对："+commands.set("password", "123").get()); System.out.println("获取<password>键的值："+commands.get("password").get()); System.out.println("系统中所有的键如下：" + commands.keys("*").get()); System.out.println("删除键password:"+commands.del("password").get()); System.out.println("判断键password是否存在："+commands.exists("password").get()); System.out.println("设置键username的过期时间为5s:"+commands.expire("username", 5L).get()); System.out.println("查看键username的剩余生存时间："+commands.ttl("username").get()); System.out.println("移除键username的生存时间："+commands.persist("username").get()); System.out.println("查看键username的剩余生存时间："+commands.ttl("username").get()); System.out.println("查看键username所存储的值的IT技术网类型："+commands.type("username").get()); connection.close(); redisClient.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30. 2.4、响应式编程

Lettuce 除了支持异步编程以外，还支持响应式编程，Lettuce 引入的响应式编程框架是​​Project Reactor​​，如果没有响应式编程经验可以先自行了解一下，访问地址​​https://projectreactor.io/​​。

响应式编程使用案例如下：

复制public class LettuceMain { public static void main(String[] args) throws Exception { RedisURI redisUri = RedisURI.builder() .withHost("127.0.0.1").withPort(6379).withPassword("111111") .withTimeout(Duration.of(10, ChronoUnit.SECONDS)) .build(); RedisClient redisClient = RedisClient.create(redisUri); StatefulRedisConnection<String, String> connection = redisClient.connect(); //

获取响应式API操作命令工具

RedisReactiveCommands<String, String> commands = connection.reactive(); Mono<String> setc = commands.set("name", "mayun"); System.out.println(setc.block()); Mono<String> getc = commands.get("name"); getc.subscribe(System.out::println); Flux<String> keys = commands.keys("*"); keys.subscribe(System.out::println); //

开启一个事务，先把count设置为1，再将count自增1

commands.multi().doOnSuccess(r -> { commands.set("count", "1").doOnNext(value -> System.out.println("count1：" + value)).subscribe(); commands.incr("count").doOnNext(value -> System.out.println("count2：" + value)).subscribe(); }).flatMap(s -> commands.exec()) .doOnNext(transactionResult -> System.out.println("transactionResult：" + transactionResult.wasDiscarded())).subscribe(); Thread.sleep(1000 * 5); connection.close(); redisClient.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31. 2.5、发布和订阅

Lettuce 还支持 redis 的消息发布和订阅，具体实现案例如下：

复制public class LettuceReactiveMain1 { public static void main(String[] args) throws Exception { RedisURI redisUri = RedisURI.builder() .withHost("127.0.0.1").withPort(6379).withPassword("111111") .withTimeout(Duration.of(10, ChronoUnit.SECONDS)) .build(); RedisClient redisClient = RedisClient.create(redisUri); //

获取发布订阅操作命令工具

StatefulRedisPubSubConnection<String, String> pubsubConn = redisClient.connectPubSub(); pubsubConn.addListener(new RedisPubSubListener<String, String>() {

@Override

public void unsubscribed(String channel, long count){ System.out.println("[unsubscribed]" + channel); }

@Override

public void subscribed(String channel, long count){ System.out.println("[subscribed]" + channel); }

@Override

public void punsubscribed(String pattern, long count){ System.out.println("[punsubscribed]" + pattern); }

@Override

public void psubscribed(String pattern, long count){ System.out.println("[psubscribed]" + pattern); }

@Override

public void message(String pattern, String channel, String message){ System.out.println("[message]" + pattern + " -> " + channel + " -> " + message); }

@Override

public void message(String channel, String message){ System.out.println("[message]" + channel + " -> " + message); } }); RedisPubSubAsyncCommands<String, String> pubsubCmd = pubsubConn.async(); pubsubCmd.psubscribe("CH"); pubsubCmd.psubscribe("CH2"); pubsubCmd.unsubscribe("CH"); Thread.sleep(100 * 5); pubsubConn.close(); redisClient.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31.32.33.34.35.36.37.38.39.40.41.42.43.44.45.46. 2.6、客户端资源与参数配置

Lettuce 客户端的通信框架集成了 Netty 的非阻塞 IO 操作，客户端资源的设置与 Lettuce 的性能、并发和事件处理紧密相关，如果不是特别熟悉客户端参数配置，不建议在没有经验的前提下凭直觉修改默认值，保持默认配置就行。

非集群环境下，具体的配置案例如下：

复制public class LettuceMain { public static void main(String[] args) throws Exception { ClientResources resources = DefaultClientResources.builder() .ioThreadPoolSize(4) //I/

O线程数

.computationThreadPoolSize(4) //

任务线程数

.build(); RedisURI redisUri = RedisURI.builder() .withHost("127.0.0.1").withPort(6379).withPassword("111111") .withTimeout(Duration.of(10, ChronoUnit.SECONDS)) .build(); ClientOptions options = ClientOptions.builder() .autoReconnect(true)//

是否自动重连

.pingBeforeActivateConnection(true)//

连接激活之前是否执行PING命令

.build(); RedisClient client = RedisClient.create(resources, redisUri); client.setOptions(options); StatefulRedisConnection<String, String> connection = client.connect(); RedisCommands<String, String> commands = connection.sync(); commands.set("name", "关羽"); System.out.println(commands.get("name")); connection.close(); client.shutdown(); resources.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.

集群环境下，具体的配置案例如下：

复制public class LettuceMain { public static void main(String[] args) throws Exception { ClientResources resources = DefaultClientResources.builder() .ioThreadPoolSize(4) //I/

O线程数

.computationThreadPoolSize(4) //

任务线程数

.build(); RedisURI redisUri = RedisURI.builder() .withHost("127.0.0.1").withPort(6379).withPassword("111111") .withTimeout(Duration.of(10, ChronoUnit.SECONDS)) .build(); ClusterClientOptions options = ClusterClientOptions.builder() .autoReconnect(true)//

是服务器租用否自动重连

.pingBeforeActivateConnection(true)//

连接激活之前是否执行PING命令

.validateClusterNodeMembership(true)//

是否校验集群节点的成员关系

.build(); RedisClusterClient client = RedisClusterClient.create(resources, redisUri); client.setOptions(options); StatefulRedisClusterConnection<String, String> connection = client.connect(); RedisAdvancedClusterCommands<String, String> commands = connection.sync(); commands.set("name", "张飞"); System.out.println(commands.get("name")); connection.close(); client.shutdown(); resources.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28. 2.7、线程池配置

Lettuce 连接设计的时候，就是线程安全的，所以一个连接可以被多个线程共享，同时 lettuce 连接默认是自动重连的，使用单连接基本可以满足业务需求，大多数情况下不需要配置连接池，多连接并不会给操作带来性能上的提升。

但在某些特殊场景下，比如事物操作，使用连接池会是一个比较好的方案，那么如何配置线程池呢？

复制public class LettuceMain { public static void main(String[] args) throws Exception { RedisURI redisUri = RedisURI.builder() .withHost("127.0.0.1") .withPort(6379) .withPassword("111111") .withTimeout(Duration.of(10, ChronoUnit.SECONDS)) .build(); RedisClient client = RedisClient.create(redisUri); //

连接池配置

GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig(); poolConfig.setMaxIdle(2); GenericObjectPool<StatefulRedisConnection<String, String>> pool = ConnectionPoolSupport.createGenericObjectPool(client::connect, poolConfig); StatefulRedisConnection<String, String> connection = pool.borrowObject(); RedisCommands<String, String> commands = connection.sync(); commands.set("name", "张飞"); System.out.println(commands.get("name")); connection.close(); pool.close(); client.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25. 2.8、主从模式配置

redis 一般采用主从复制模式，搭建高可用的架构，简单的说就一个主节点，多个从节点，自动从主节点同步最新数据。

Lettuce 支持自动发现主从模式下的节点信息，然后保存到本地，具体配置如下：

复制public class LettuceMain { public static void main(String[] args) throws Exception { //这里只需要配置一个节点的连接信息，不一定需要是主节点的信息，从节点也可以;

可以自动发现主从节点

RedisURI uri = RedisURI.builder().withHost("192.168.31.111").withPort(6379).withPassword("123456").build(); RedisClient client = RedisClient.create(uri); StatefulRedisMasterReplicaConnection<String, String> connection = MasterReplica.connect(client, StringCodec.UTF8, uri); //

从节点读取数据

connection.setReadFrom(ReadFrom.REPLICA); RedisCommands<String, String> commands = connection.sync(); commands.set("name", "张飞"); System.out.println(commands.get("name")); connection.close(); client.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.

当然我们也可以手动指定集群节点来加载，具体配置如下：

复制public class LettuceMain { public static void main(String[] args) throws Exception { //

集群节点

List<RedisURI> uris = new ArrayList(); uris.add(RedisURI.builder().withHost("192.168.31.111").withPort(6379).withPassword("111111").build()); uris.add(RedisURI.builder().withHost("192.168.31.112").withPort(6379).withPassword("111111").build()); uris.add(RedisURI.builder().withHost("192.168.31.113").withPort(6379).withPassword("111111").build()); RedisClient client = RedisClient.create(); StatefulRedisMasterReplicaConnection<String, String> connection = MasterReplica.connect(client, StringCodec.UTF8, uris); //

从节点读取数据

connection.setReadFrom(ReadFrom.REPLICA); RedisCommands<String, String> commands = connection.sync(); commands.set("name", "张飞"); System.out.println(commands.get("name")); connection.close(); client.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22. 2.9、哨兵模式配置

哨兵模式，也是 redis 实现服务高可用的一大亮点，具体配置实现如下：

复制public class LettuceMain { public static void main(String[] args) throws Exception { //

集群节点

List<RedisURI> uris = new ArrayList(); uris.add(RedisURI.builder().withSentinel("192.168.31.111", 26379).withSentinelMasterId("mymaster").withPassword("123456").build()); uris.add(RedisURI.builder().withSentinel("192.168.31.112", 26379).withSentinelMasterId("mymaster").withPassword("123456").build()); uris.add(RedisURI.builder().withSentinel("192.168.31.113", 26379).withSentinelMasterId("mymaster").withPassword("123456").build()); RedisClient client = RedisClient.create(); StatefulRedisMasterReplicaConnection<String, String> connection = MasterReplica.connect(client, StringCodec.UTF8, uris); //

从节点读取数据

connection.setReadFrom(ReadFrom.REPLICA); RedisCommands<String, String> commands = connection.sync(); commands.set("name", "赵云"); System.out.println(commands.get("name")); connection.close(); client.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22. 2.10、Cluster 集群模式配置

Cluster 集群模式，是之后推出的一种高可用的架构模型，主要是采用分片方式来存储数据，具体配置如下：

复制public class LettuceReactiveMain4 { public static void main(String[] args) throws Exception { Set<RedisURI> uris = new HashSet<>(); uris.add(RedisURI.builder().withHost("192.168.31.111").withPort(7000).withPassword("123456").build()); uris.add(RedisURI.builder().withHost("192.168.31.112").withPort(7000).withPassword("123456").build()); uris.add(RedisURI.builder().withHost("192.168.31.113").withPort(7000).withPassword("123456").build()); uris.add(RedisURI.builder().withHost("192.168.31.114").withPort(7000).withPassword("123456").build()); uris.add(RedisURI.builder().withHost("192.168.31.115").withPort(7000).withPassword("123456").build()); uris.add(RedisURI.builder().withHost("192.168.31.116").withPort(7001).withPassword("123456").build()); RedisClusterClient client = RedisClusterClient.create(uris); StatefulRedisClusterConnection<String, String> connection = client.connect(); RedisAdvancedClusterCommands<String, String> commands = connection.sync(); commands.set("name", "关羽"); System.out.println(commands.get("name")); //选择从节点,

只读

NodeSelection<String, String> replicas = commands.replicas(); NodeSelectionCommands<String, String> nodeSelectionCommands = replicas.commands(); Executions<List<String>> keys = nodeSelectionCommands.keys("*"); keys.forEach(key -> System.out.println(key)); connection.close(); client.shutdown(); }}1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.

三、小结

Lettuce 相比老牌的 Jedis 客户端，功能更加强大，不仅解决了线程安全的问题，还支持异步和响应式编程，支持集群，Sentinel，管道和编码器等等功能。

以上介绍的可能只是冰山一角，如果想要了解更多的信息，可以访问它的官网地址：https://lettuce.io/。

内容难免有所遗漏，欢迎网友批评指出！

四、参考

1、博客园 - throwable - Redis高级客户端Lettuce详解

2、[博客园 - 且行且码 - Redis入门实战(5)-lettuce操作redis