Redis實戰(zhàn)之Lettuce的使用技巧詳解
更新時間：2022年12月23日 10:08:49 作者：鴨血粉絲Tang
Lettuce?是?Redis?的一款高級?Java?客戶端，與?Jedis?并列成為最熱門的客戶端之一，目前已成為?SpringBoot?2.0?版本默認的?redis?客戶端。本文主要和大家講講Lettuce的使用技巧，感興趣的可以了解一下
一、摘要
Lettuce 是 Redis 的一款高級 Java 客戶端，與 Jedis 并列成為最熱門的客戶端之一，目前已成為 SpringBoot 2.0 版本默認的 redis 客戶端。
相比老牌 Jedis，Lettuce 屬于后起之秀，不僅功能豐富，而且提供了很多新的功能特性，比如異步操作、響應(yīng)式編程等等，同時還解決了 Jedis 中線程不安全的問題。
廢話不多說了，如何使用呢？請看下文！
二、Lettuce
2.1、基本使用
首先，創(chuàng)建一個 maven 項目，引入lettuce-core包，就可以使用了。
<dependency> ??<groupId>io.lettuce</groupId> ??<artifactId>lettuce-core</artifactId> ??<version>5.3.1.RELEASE</version> </dependency>
使用 lettuce 連接 redis，測試是否能正常聯(lián)通！
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();
????}
}
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，我們以同步操作字符串為例，Lettuce 的 api 操作如下！
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();
????????//獲取同步操作命令工具
????????RedisCommands<String,?String>?commands?=?connection.sync();
????????System.out.println("清空數(shù)據(jù)："+commands.flushdb());
????????System.out.println("判斷某個鍵是否存在："+commands.exists("username"));
????????System.out.println("新增<'username','xmr'>的鍵值對："+commands.set("username",?"xmr"));
????????System.out.println("新增<'password','password'>的鍵值對："+commands.set("password",?"123"));
????????System.out.println("獲取<'password'>鍵的值："+commands.get("password"));
????????System.out.println("系統(tǒng)中所有的鍵如下："?+?commands.keys("*"));
????????System.out.println("刪除鍵password:"+commands.del("password"));
????????System.out.println("判斷鍵password是否存在："+commands.exists("password"));
????????System.out.println("設(shè)置鍵username的過期時間為5s:"+commands.expire("username",?5L));
????????System.out.println("查看鍵username的剩余生存時間："+commands.ttl("username"));
????????System.out.println("移除鍵username的生存時間："+commands.persist("username"));
????????System.out.println("查看鍵username的剩余生存時間："+commands.ttl("username"));
????????System.out.println("查看鍵username所存儲的值的類型："+commands.type("username"));
????????connection.close();
????????redisClient.shutdown();
????}
}
2.3、異步操作
除此之外，Lettuce 還支持異步操作，將上面的操作改成異步處理，結(jié)果如下！
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();
????????//獲取異步操作命令工具
????????RedisAsyncCommands<String,?String>?commands?=?connection.async();
????????System.out.println("清空數(shù)據(jù)："+commands.flushdb().get());
????????System.out.println("判斷某個鍵是否存在："+commands.exists("username").get());
????????System.out.println("新增<'username','xmr'>的鍵值對："+commands.set("username",?"xmr").get());
????????System.out.println("新增<'password','password'>的鍵值對："+commands.set("password",?"123").get());
????????System.out.println("獲取<'password'>鍵的值："+commands.get("password").get());
????????System.out.println("系統(tǒng)中所有的鍵如下："?+?commands.keys("*").get());
????????System.out.println("刪除鍵password:"+commands.del("password").get());
????????System.out.println("判斷鍵password是否存在："+commands.exists("password").get());
????????System.out.println("設(shè)置鍵username的過期時間為5s:"+commands.expire("username",?5L).get());
????????System.out.println("查看鍵username的剩余生存時間："+commands.ttl("username").get());
????????System.out.println("移除鍵username的生存時間："+commands.persist("username").get());
????????System.out.println("查看鍵username的剩余生存時間："+commands.ttl("username").get());
????????System.out.println("查看鍵username所存儲的值的類型："+commands.type("username").get());
????????connection.close();
????????redisClient.shutdown();
????}
}
2.4、響應(yīng)式編程
Lettuce 除了支持異步編程以外，還支持響應(yīng)式編程，Lettuce 引入的響應(yīng)式編程框架是Project Reactor，如果沒有響應(yīng)式編程經(jīng)驗可以先自行了解一下，訪問地址https://projectreactor.io/。
響應(yīng)式編程使用案例如下：
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();
????????//獲取響應(yīng)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);
????????//開啟一個事務(wù)，先把count設(shè)置為1，再將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();
????}
}
2.5、發(fā)布和訂閱
Lettuce 還支持 redis 的消息發(fā)布和訂閱，具體實現(xiàn)案例如下：
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);
????????//獲取發(fā)布訂閱操作命令工具
????????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();
????}
}
2.6、客戶端資源與參數(shù)配置
Lettuce 客戶端的通信框架集成了 Netty 的非阻塞 IO 操作，客戶端資源的設(shè)置與 Lettuce 的性能、并發(fā)和事件處理緊密相關(guān)，如果不是特別熟悉客戶端參數(shù)配置，不建議在沒有經(jīng)驗的前提下憑直覺修改默認值，保持默認配置就行。
非集群環(huán)境下，具體的配置案例如下：
public?class?LettuceMain?{
????public?static?void?main(String[]?args)?throws?Exception?{
????????ClientResources?resources?=?DefaultClientResources.builder()
????????????????.ioThreadPoolSize(4)?//I/O線程數(shù)
????????????????.computationThreadPoolSize(4)?//任務(wù)線程數(shù)
????????????????.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)//是否自動重連
????????????????.pingBeforeActivateConnection(true)//連接激活之前是否執(zhí)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",?"關(guān)羽");
????????System.out.println(commands.get("name"));
????????connection.close();
????????client.shutdown();
????????resources.shutdown();
????}
}
集群環(huán)境下，具體的配置案例如下：
public?class?LettuceMain?{
????public?static?void?main(String[]?args)?throws?Exception?{
????????ClientResources?resources?=?DefaultClientResources.builder()
????????????????.ioThreadPoolSize(4)?//I/O線程數(shù)
????????????????.computationThreadPoolSize(4)?//任務(wù)線程數(shù)
????????????????.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)//是否自動重連
????????????????.pingBeforeActivateConnection(true)//連接激活之前是否執(zhí)行PING命令
????????????????.validateClusterNodeMembership(true)//是否校驗集群節(jié)點的成員關(guān)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",?"張飛");
????????System.out.println(commands.get("name"));
????????connection.close();
????????client.shutdown();
????????resources.shutdown();
????}
}
2.7、線程池配置
Lettuce 連接設(shè)計的時候，就是線程安全的，所以一個連接可以被多個線程共享，同時 lettuce 連接默認是自動重連的，使用單連接基本可以滿足業(yè)務(wù)需求，大多數(shù)情況下不需要配置連接池，多連接并不會給操作帶來性能上的提升。
但在某些特殊場景下，比如事物操作，使用連接池會是一個比較好的方案，那么如何配置線程池呢？
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);
????????//連接池配置
????????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",?"張飛");
????????System.out.println(commands.get("name"));
????????connection.close();
????????pool.close();
????????client.shutdown();
????}
}
2.8、主從模式配置
redis 一般采用主從復(fù)制模式，搭建高可用的架構(gòu)，簡單的說就一個主節(jié)點，多個從節(jié)點，自動從主節(jié)點同步最新數(shù)據(jù)。
Lettuce 支持自動發(fā)現(xiàn)主從模式下的節(jié)點信息，然后保存到本地，具體配置如下：
public?class?LettuceMain?{
????public?static?void?main(String[]?args)?throws?Exception?{
????????//這里只需要配置一個節(jié)點的連接信息，不一定需要是主節(jié)點的信息，從節(jié)點也可以;可以自動發(fā)現(xiàn)主從節(jié)點
????????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);
????????//從節(jié)點讀取數(shù)據(jù)
????????connection.setReadFrom(ReadFrom.REPLICA);
????????RedisCommands<String,?String>?commands?=?connection.sync();
????????commands.set("name",?"張飛");
????????System.out.println(commands.get("name"));
????????connection.close();
????????client.shutdown();
????}
}
當然我們也可以手動指定集群節(jié)點來加載，具體配置如下：
public?class?LettuceMain?{
????public?static?void?main(String[]?args)?throws?Exception?{
????????//集群節(jié)點
????????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);
????????//從節(jié)點讀取數(shù)據(jù)
????????connection.setReadFrom(ReadFrom.REPLICA);
????????RedisCommands<String,?String>?commands?=?connection.sync();
????????commands.set("name",?"張飛");
????????System.out.println(commands.get("name"));
????????connection.close();
????????client.shutdown();
????}
}
2.9、哨兵模式配置
哨兵模式，也是 redis 實現(xiàn)服務(wù)高可用的一大亮點，具體配置實現(xiàn)如下：
public?class?LettuceMain?{
????public?static?void?main(String[]?args)?throws?Exception?{
????????//集群節(jié)點
????????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);
????????//從節(jié)點讀取數(shù)據(jù)
????????connection.setReadFrom(ReadFrom.REPLICA);
????????RedisCommands<String,?String>?commands?=?connection.sync();
????????commands.set("name",?"趙云");
????????System.out.println(commands.get("name"));
????????connection.close();
????????client.shutdown();
????}
}
2.10、Cluster 集群模式配置
Cluster 集群模式，是之后推出的一種高可用的架構(gòu)模型，主要是采用分片方式來存儲數(shù)據(jù)，具體配置如下：
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",?"關(guān)羽");
????????System.out.println(commands.get("name"));
????????//選擇從節(jié)點,只讀
????????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();
????}
}
三、小結(jié)
Lettuce 相比老牌的 Jedis 客戶端，功能更加強大，不僅解決了線程安全的問題，還支持異步和響應(yīng)式編程，支持集群，Sentinel，管道和編碼器等等功能。
以上介紹的可能只是冰山一角，如果想要了解更多的信息，可以訪問它的官網(wǎng)地址：https://lettuce.io/
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