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Redis之Lettuce怎麼使用

WBOY
發布： 2023-05-28 21:51:24
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一、摘要

Lettuce 是 Redis 的一款高級 Java 用戶端，與 Jedis 並列成為最熱門的客戶端之一，目前已成為 SpringBoot 2.0 版本預設的 redis 用戶端。

相比老牌 Jedis，Lettuce 屬於後起之秀，不僅功能豐富，而且提供了許多新的功能特性，例如非同步操作、響應式程式設計等等，同時還解決了 Jedis 中線程不安全的問題。

二、Lettuce

2.1、基本使用

首先，建立一個 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>
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使用 lettuce 連接 redis，測試是否能正常聯通！ 

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();
    }
}
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2.2、同步操作

基本上只要是 Jedis 支援的同步指令操作，Lettuce 都會支援。

下面，我們以同步運算字串為例，Lettuce 的 api 運算如下！ 

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();
        //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<&#39;username&#39;,&#39;xmr&#39;>的键值对："+commands.set("username", "xmr"));
        System.out.println("新增<&#39;password&#39;,&#39;password&#39;>的键值对："+commands.set("password", "123"));
        System.out.println("获取<&#39;password&#39;>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();
    }
}
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2.3、非同步操作

除此之外，Lettuce 也支援非同步操作，將上面的操作改成非同步處理，結果如下！ 

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();
        //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<&#39;username&#39;,&#39;xmr&#39;>的键值对："+commands.set("username", "xmr").get());
        System.out.println("新增<&#39;password&#39;,&#39;password&#39;>的键值对："+commands.set("password", "123").get());
        System.out.println("获取<&#39;password&#39;>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所存储的值的类型："+commands.type("username").get());

        connection.close();
        redisClient.shutdown();
    }
}
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2.4、響應式編程

Lettuce 除了支援非同步編程以外，還支援響應式編程，Lettuce 引入的響應式編程框架是Project Reactor，如果沒有響應式程式設計經驗可以先自行了解。

響應式程式設計使用案例如下：

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();
        //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();
    }
}
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2.5、發布和訂閱

Lettuce 也支援redis 的訊息發布和訂閱，具體實作案例如下：

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);
        //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();
    }
}
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2.6、客戶端資源與參數配置

Lettuce 用戶端的通訊框架整合了Netty 的非阻塞IO 操作，客戶端資源的設定與Lettuce 的效能、並發和事件處理緊密相關，如果不是特別熟悉客戶端參數配置，不建議在沒有經驗的前提下憑直覺修改預設值，保持預設配置就行。

非叢集環境下，具體的設定案例如下：

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();
    }
}
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叢集環境下，具體的設定案例如下：

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();
    }
}
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2.7、執行緒池配置

Lettuce 連接設計的時候，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 連接預設是自動重連的，使用單連接基本上可以滿足業務需求，大多數情況下不需要配置連接池，多重連線不會為操作帶來效能上的提升。

但在某些特殊場景下，例如事物操作，使用連線池會是比較好的方案，那麼如何配置執行緒池呢？ 

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);
        //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();
    }
}
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2.8、主從模式配置

redis 一般採用主從複製模式，搭建高可用的架構，簡單的說就一個主節點，多個從節點，自動從主節點同步最新資料。

Lettuce 支援自動發現主從模式下的節點信息，然後保存到本地，具體配置如下：

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();
    }
}
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當然我們也可以手動指定集群節點來加載，具體配置如下：

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();
    }
}
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2.9、哨兵模式配置

哨兵模式，也是redis 實現服務高可用的一大亮點，具體配置實現如下：

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();
    }
}
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2.10、Cluster 集群模式配置

Cluster 叢集模式，是之後推出的一種高可用的架構模型，主要是採用分片方式來儲存數據，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", "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();
    }
}
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以上是Redis之Lettuce怎麼使用的詳細內容。更多資訊請關注PHP中文網其他相關文章！

相關標籤：
redis lettuce
來源：yisu.com
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