• Java通过Lettuce访问Redis主从，哨兵，集群

    操作

    • 首先需要maven导入依赖

    1. <dependency>
    2.     <groupId>io.lettucegroupId>
    3.     <artifactId>lettuce-coreartifactId>
    4.     <version>6.3.0.RELEASEversion>
    5. dependency>

    • 测试连接

    1. public class LettuceDemo {
    2.  
    3.     public static void main(String[] args) {
    4.         RedisURI redisUri = RedisURI.builder()
    5.                 .withHost("127.0.0.1")
    6.                 .withPort(6379)
    7.                 .withPassword("123456")
    8.                 .withTimeout(Duration.of(10, ChronoUnit.SECONDS))
    9.                 .build();
    10.         RedisClient redisClient = RedisClient.create(redisUri);
    11.         StatefulRedisConnection connection = redisClient.connect();
    12.         RedisCommands commands = connection.sync();
    13.         System.out.println(commands.ping());
    14.         connection.close();
    15.         redisClient.shutdown();
    16.     }
    17. }

    • 同步操作

    1. public class LettuceSyncDemo {
    2.  
    3.     public static void main(String[] args) {
    4.         RedisURI redisUri = RedisURI.builder()
    5.                 .withHost("127.0.0.1").withPort(6379).withPassword("123456")
    6.                 .withTimeout(Duration.of(10, ChronoUnit.SECONDS))
    7.                 .build();
    8.         RedisClient redisClient = RedisClient.create(redisUri);
    9.         StatefulRedisConnection connection = redisClient.connect();
    10.         //获取同步操作命令工具
    11.         RedisCommands commands = connection.sync();
    12.  
    13.         System.out.println("清空数据："+commands.flushdb());
    14.         System.out.println("判断某个键是否存在："+commands.exists("username"));
    15.         System.out.println("新增<'username','xmr'>的键值对："+commands.set("username", "xmr"));
    16.         System.out.println("新增<'password','password'>的键值对："+commands.set("password", "123"));
    17.         System.out.println("获取<'password'>键的值："+commands.get("password"));
    18.         System.out.println("系统中所有的键如下：" + commands.keys("*"));
    19.         System.out.println("删除键password:"+commands.del("password"));
    20.         System.out.println("判断键password是否存在："+commands.exists("password"));
    21.         System.out.println("设置键username的过期时间为5s:"+commands.expire("username", 5L));
    22.         System.out.println("查看键username的剩余生存时间："+commands.ttl("username"));
    23.         System.out.println("移除键username的生存时间："+commands.persist("username"));
    24.         System.out.println("查看键username的剩余生存时间："+commands.ttl("username"));
    25.         System.out.println("查看键username所存储的值的类型："+commands.type("username"));
    26.  
    27.         connection.close();
    28.         redisClient.shutdown();
    29.     }
    30. }

    • 异步操作

    1. public class LettuceASyncDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         RedisURI redisUri = RedisURI.builder()
    5.                 .withHost("127.0.0.1").withPort(6379).withPassword("123456")
    6.                 .withTimeout(Duration.of(10, ChronoUnit.SECONDS))
    7.                 .build();
    8.         RedisClient redisClient = RedisClient.create(redisUri);
    9.         StatefulRedisConnection connection = redisClient.connect();
    10.         //获取异步操作命令工具
    11.         RedisAsyncCommands commands = connection.async();
    12.  
    13.         System.out.println("清空数据："+commands.flushdb().get());
    14.         System.out.println("判断某个键是否存在："+commands.exists("username").get());
    15.         System.out.println("新增<'username','xmr'>的键值对："+commands.set("username", "xmr").get());
    16.         System.out.println("新增<'password','password'>的键值对："+commands.set("password", "123").get());
    17.         System.out.println("获取<'password'>键的值："+commands.get("password").get());
    18.         System.out.println("系统中所有的键如下：" + commands.keys("*").get());
    19.         System.out.println("删除键password:"+commands.del("password").get());
    20.         System.out.println("判断键password是否存在："+commands.exists("password").get());
    21.         System.out.println("设置键username的过期时间为5s:"+commands.expire("username", 5L).get());
    22.         System.out.println("查看键username的剩余生存时间："+commands.ttl("username").get());
    23.         System.out.println("移除键username的生存时间："+commands.persist("username").get());
    24.         System.out.println("查看键username的剩余生存时间："+commands.ttl("username").get());
    25.         System.out.println("查看键username所存储的值的类型："+commands.type("username").get());
    26.  
    27.         connection.close();
    28.         redisClient.shutdown();
    29.     }
    30. }

            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，框架官网：https://projectreactor.io/

    1. public class LettuceReactorDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         RedisURI redisUri = RedisURI.builder()
    5.                 .withHost("127.0.0.1").withPort(6379).withPassword("123456")
    6.                 .withTimeout(Duration.of(10, ChronoUnit.SECONDS))
    7.                 .build();
    8.         RedisClient redisClient = RedisClient.create(redisUri);
    9.         StatefulRedisConnection connection = redisClient.connect();
    10.         //获取响应式API操作命令工具
    11.         RedisReactiveCommands commands = connection.reactive();
    12.  
    13.         Mono setc = commands.set("name", "mayun");
    14.         System.out.println(setc.block());
    15.         Mono getc = commands.get("name");
    16.         getc.subscribe(System.out::println);
    17.         Flux keys = commands.keys("*");
    18.         keys.subscribe(System.out::println);
    19.  
    20.         //开启一个事务，先把count设置为1，再将count自增1
    21.         commands.multi().doOnSuccess(r -> {
    22.             commands.set("count", "1").doOnNext(value -> System.out.println("count1：" +  value)).subscribe();
    23.             commands.incr("count").doOnNext(value -> System.out.println("count2：" +  value)).subscribe();
    24.         }).flatMap(s -> commands.exec())
    25.                 .doOnNext(transactionResult -> System.out.println("transactionResult：" + transactionResult.wasDiscarded())).subscribe();
    26.  
    27.         Thread.sleep(1000 * 5);
    28.         connection.close();
    29.         redisClient.shutdown();
    30.     }
    31. }

    • 发布和订阅

    1. public class LettuceReactiveDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         RedisURI redisUri = RedisURI.builder()
    5.                 .withHost("127.0.0.1").withPort(6379).withPassword("123456")
    6.                 .withTimeout(Duration.of(10, ChronoUnit.SECONDS))
    7.                 .build();
    8.         RedisClient redisClient = RedisClient.create(redisUri);
    9.         //获取发布订阅操作命令工具
    10.         StatefulRedisPubSubConnection pubsubConn = redisClient.connectPubSub();
    11.         pubsubConn.addListener(new RedisPubSubListener() {
    12.             @Override
    13.             public void unsubscribed(String channel, long count) {
    14.                 System.out.println("[unsubscribed]" + channel);
    15.             }
    16.             @Override
    17.             public void subscribed(String channel, long count) {
    18.                 System.out.println("[subscribed]" + channel);
    19.             }
    20.             @Override
    21.             public void punsubscribed(String pattern, long count) {
    22.                 System.out.println("[punsubscribed]" + pattern);
    23.             }
    24.             @Override
    25.             public void psubscribed(String pattern, long count) {
    26.                 System.out.println("[psubscribed]" + pattern);
    27.             }
    28.             @Override
    29.             public void message(String pattern, String channel, String message) {
    30.                 System.out.println("[message]" + pattern + " -> " + channel + " -> " + message);
    31.             }
    32.             @Override
    33.             public void message(String channel, String message) {
    34.                 System.out.println("[message]" + channel + " -> " + message);
    35.             }
    36.         });
    37.         RedisPubSubAsyncCommands pubsubCmd = pubsubConn.async();
    38.         pubsubCmd.psubscribe("CH");
    39.         pubsubCmd.psubscribe("CH2");
    40.         pubsubCmd.unsubscribe("CH");
    41.  
    42.         Thread.sleep(100 * 5);
    43.         pubsubConn.close();
    44.         redisClient.shutdown();
    45.     }
    46. }

    • 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，如果不熟悉客户端参数配置，不推荐修改默认值，保持默认配置即可。

            - 非集群模式

    1. public class LettuceDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         ClientResources resources = DefaultClientResources.builder()
    5.                 .ioThreadPoolSize(4) //I/O线程数
    6.                 .computationThreadPoolSize(4) //任务线程数
    7.                 .build();
    8.         RedisURI redisUri = RedisURI.builder()
    9.                 .withHost("127.0.0.1").withPort(6379).withPassword("123456")
    10.                 .withTimeout(Duration.of(10, ChronoUnit.SECONDS))
    11.                 .build();
    12.         ClientOptions options = ClientOptions.builder()
    13.                 .autoReconnect(true)//是否自动重连
    14.                 .pingBeforeActivateConnection(true)//连接激活之前是否执行PING命令
    15.                 .build();
    16.         RedisClient client = RedisClient.create(resources, redisUri);
    17.         client.setOptions(options);
    18.         StatefulRedisConnection connection = client.connect();
    19.         RedisCommands commands = connection.sync();
    20.         commands.set("name", "关羽");
    21.         System.out.println(commands.get("name"));
    22.  
    23.         connection.close();
    24.         client.shutdown();
    25.         resources.shutdown();
    26.     }
    27. }

            - 集群模式

    1. public class LettuceDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         ClientResources resources = DefaultClientResources.builder()
    5.                 .ioThreadPoolSize(4) //I/O线程数
    6.                 .computationThreadPoolSize(4) //任务线程数
    7.                 .build();
    8.         RedisURI redisUri = RedisURI.builder()
    9.                 .withHost("127.0.0.1").withPort(6379).withPassword("123456")
    10.                 .withTimeout(Duration.of(10, ChronoUnit.SECONDS))
    11.                 .build();
    12.         ClusterClientOptions options = ClusterClientOptions.builder()
    13.                 .autoReconnect(true)//是否自动重连
    14.                 .pingBeforeActivateConnection(true)//连接激活之前是否执行PING命令
    15.                 .validateClusterNodeMembership(true)//是否校验集群节点的成员关系
    16.                 .build();
    17.         RedisClusterClient client = RedisClusterClient.create(resources, redisUri);
    18.         client.setOptions(options);
    19.         StatefulRedisClusterConnection connection = client.connect();
    20.         RedisAdvancedClusterCommands commands = connection.sync();
    21.         commands.set("name", "张飞");
    22.         System.out.println(commands.get("name"));
    23.  
    24.         connection.close();
    25.         client.shutdown();
    26.         resources.shutdown();
    27.     }
    28. }

    • 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，配置方法如下

    1. public class LettuceDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         RedisURI redisUri = RedisURI.builder()
    5.                 .withHost("127.0.0.1")
    6.                 .withPort(6379)
    7.                 .withPassword("123456")
    8.                 .withTimeout(Duration.of(10, ChronoUnit.SECONDS))
    9.                 .build();
    10.         RedisClient client = RedisClient.create(redisUri);
    11.         //连接池配置
    12.         GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
    13.         poolConfig.setMaxIdle(2);
    14.  
    15.         GenericObjectPool> pool = ConnectionPoolSupport.createGenericObjectPool(client::connect, poolConfig);
    16.         StatefulRedisConnection connection = pool.borrowObject();
    17.         RedisCommands commands = connection.sync();
    18.         commands.set("name", "张飞");
    19.         System.out.println(commands.get("name"));
    20.  
    21.         connection.close();
    22.         pool.close();
    23.         client.shutdown();
    24.     }
    25. }

    • 主从模式

           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。

             - 自动发现主从模式下所有节点

    1. public class LettuceDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         //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
    5.         RedisURI uri = RedisURI.builder().withHost("192.168.31.111").withPort(6379).withPassword("123456").build();
    6.         RedisClient client = RedisClient.create(uri);
    7.         StatefulRedisMasterReplicaConnection connection = MasterReplica.connect(client, StringCodec.UTF8, uri);
    8.         //从节点读取数据
    9.         connection.setReadFrom(ReadFrom.REPLICA);
    10.  
    11.         RedisCommands commands = connection.sync();
    12.         commands.set("name", "张飞");
    13.         System.out.println(commands.get("name"));
    14.  
    15.         connection.close();
    16.         client.shutdown();
    17.     }
    18. }

             - 手动指定主从模式下集群节点

    1. public class LettuceDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         //集群节点
    5.         List uris = new ArrayList();
    6.         uris.add(RedisURI.builder().withHost("192.168.79.135").withPort(6379).withPassword("123456").build());
    7.         uris.add(RedisURI.builder().withHost("192.168.79.136").withPort(6379).withPassword("123456").build());
    8.         uris.add(RedisURI.builder().withHost("192.168.79.137").withPort(6379).withPassword("123456").build());
    9.  
    10.         RedisClient client = RedisClient.create();
    11.         StatefulRedisMasterReplicaConnection connection = MasterReplica.connect(client, StringCodec.UTF8, uris);
    12.         //从节点读取数据
    13.         connection.setReadFrom(ReadFrom.REPLICA);
    14.  
    15.         RedisCommands commands = connection.sync();
    16.         commands.set("name", "张飞");
    17.         System.out.println(commands.get("name"));
    18.  
    19.         connection.close();
    20.         client.shutdown();
    21.     }
    22. }

    • 哨兵模式

            哨兵模式可以实现当主节点下线时，通过选举的方式将从节点升级为主节点

    1. public class LettuceDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         //集群节点
    5.         List uris = new ArrayList();
    6.         uris.add(RedisURI.builder().withSentinel("192.168.79.135", 26379).withSentinelMasterId("mymaster").withPassword("123456").build());
    7.         uris.add(RedisURI.builder().withSentinel("192.168.79.135", 26379).withSentinelMasterId("mymaster").withPassword("123456").build());
    8.         uris.add(RedisURI.builder().withSentinel("192.168.79.135", 26379).withSentinelMasterId("mymaster").withPassword("123456").build());
    9.  
    10.         RedisClient client = RedisClient.create();
    11.         StatefulRedisMasterReplicaConnection connection = MasterReplica.connect(client, StringCodec.UTF8, uris);
    12.         //从节点读取数据
    13.         connection.setReadFrom(ReadFrom.REPLICA);
    14.  
    15.         RedisCommands commands = connection.sync();
    16.         commands.set("name", "赵云");
    17.         System.out.println(commands.get("name"));
    18.  
    19.         connection.close();
    20.         client.shutdown();
    21.     }
    22. }

    • Cluster 集群模式

            基于主从模式和哨兵模式的理念，推出的高可用的架构模型，主要是采用分片方式来存储数据

    1. public class LettuceReactiveDemo {
    2.  
    3.     public static void main(String[] args) throws Exception {
    4.         Set uris = new HashSet<>();
    5.         uris.add(RedisURI.builder().withHost("192.168.79.135").withPort(5001).withPassword("123456").build());
    6.         uris.add(RedisURI.builder().withHost("192.168.79.135").withPort(5002).withPassword("123456").build());
    7.         uris.add(RedisURI.builder().withHost("192.168.79.135").withPort(5003).withPassword("123456").build());
    8.         uris.add(RedisURI.builder().withHost("192.168.79.136").withPort(5001).withPassword("123456").build());
    9.         uris.add(RedisURI.builder().withHost("192.168.79.136").withPort(5002).withPassword("123456").build());
    10.         uris.add(RedisURI.builder().withHost("192.168.79.136").withPort(5003).withPassword("123456").build());
    11.  
    12.         RedisClusterClient client = RedisClusterClient.create(uris);
    13.         StatefulRedisClusterConnection connection = client.connect();
    14.         RedisAdvancedClusterCommands commands = connection.sync();
    15.         commands.set("name", "关羽");
    16.         System.out.println(commands.get("name"));
    17.  
    18.         //选择从节点,只读
    19.         NodeSelection replicas = commands.replicas();
    20.         NodeSelectionCommands nodeSelectionCommands = replicas.commands();
    21.         Executions> keys = nodeSelectionCommands.keys("*");
    22.         keys.forEach(key -> System.out.println(key));
    23.  
    24.         connection.close();
    25.         client.shutdown();
    26.     }
    27. }

    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。

    了解更多的信息，可以访问官网地址：https://lettuce.io/

    参考：

    【进阶篇】Redis实战之Lettuce使用技巧详解 - 知乎

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  • 原文地址：https://blog.csdn.net/ymq267/article/details/134464769