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第二十节:学习Redis缓存数据库实现增删改查(自学Spring boot 3.x的第五天)

这节记录下如何使用redis缓存数据库。

第一步:

先在服务器端安装redis,

下载地址:Releases · tporadowski/redis · GitHub。

第二步:

安装redis客户端可视化管理软件redisDesktopmanager

Redis Desktop Manager - Download

第三步:

设置redis缓存服务器的密码。

方式一(临时密码):打开redis-server.exe,输入config set requirepass 密码
方式二:永久密码,修改redis的conf文件,在conf中搜索requirepass。记得修改了以后重启(先停止再启动)redis的服务,不然不生效。

第四步:Redis Desktop Manager管理软件,测试是否能连接上Redis服务器。

​​
在这里插入图片描述

第五步:开始配置Springboot中的redis

在application-local.yml文章中


spring:
  datasource:
    url: jdbc:mysql://localhost:3306/test123?useSSL=false&characterEncoding=UTF-8&serverTimezone=UTC
    username: root
    password:
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.zaxxer.hikari.HikariDataSource
    # 连接池
    hikari:
      minimum-idle: 10
      maximum-pool-size: 20
      idle-timeout: 300000
      max-lifetime: 1800000
      connection-timeout: 30000
      pool-name: SpringHikariCP

  data:
    redis:
      host: 127.0.0.1
      password: 123456

第六步:编写测试代码

 @PostMapping
    public void save(){
      List<Student> studentList =   studentService.list();
      stringRedisTemplate.opsForValue().set("studentList", JSONUtil.toJsonStr(studentList));
    }

    @GetMapping
    public List<Student> list(){
        List<Student> list = JSONUtil.toList(stringRedisTemplate.opsForValue().get("studentList"),Student.class);
        return list;
    }

    @PutMapping
    public void update(){
        List<Student> list = JSONUtil.toList(stringRedisTemplate.opsForValue().get("studentList"),Student.class);
        Student student1 = new Student();
        student1.setName("小王");
        student1.setAge(18);
        student1.setCreate_time(new Date());
        list.add(student1);
        stringRedisTemplate.opsForValue().set("studentList",JSONUtil.toJsonStr(list));
        return ;
    }
    @DeleteMapping
    public void delete(){
        stringRedisTemplate.delete("studentList");
    }

第七步:观察redis存储结果

在这里插入图片描述

上面记录了操作步骤。
那么接下来我们对代码进行分析。

一:redis是如何获取applocation.yml中的配置参数的?

Redis并不直接“获取”application.yml中的配置参数,而是Spring Boot框架在启动过程中读取这些配置参数,并据此配置Redis连接。应用程序通过Spring Boot提供的接口(如RedisTemplate)与Redis进行交互,而无需直接关心连接参数的配置。这种方式简化了应用程序与Redis的集成过程,提高了开发效率。

二:StringRedisTemplate类什么?

StringRedisTemplate类是Spring Data Redis提供的一个用于操作Redis的模板类。它专门用于处理Redis中的String类型数据,提供了一系列简化操作的方法,使开发者可以方便地进行数据的读取、写入和删除等操作,而无需关心底层Redis的连接和数据序列化等细节。
主要特点和用法
简化的操作方法:StringRedisTemplate封装了一系列简化的操作方法,如设置、获取、删除String类型数据等,开发者可以直接调用这些方法来进行操作,而无需关心Redis的底层实现。
与Spring集成:StringRedisTemplate是基于Spring框架提供的RedisTemplate实现的,因此可以与Spring应用程序无缝集成,通过依赖注入的方式进行使用。
支持事务:StringRedisTemplate支持在事务中进行操作,可以保证多个操作的原子性,确保数据的一致性。
支持序列化:StringRedisTemplate支持将Java对象序列化成Redis数据格式,以及将Redis数据反序列化成Java对象,方便开发者进行数据存取操作。
提供回调接口:StringRedisTemplate还提供了一些回调接口,如RedisCallback和SessionCallback,开发者可以通过这些接口来执行自定义的Redis操作,更灵活地控制Redis的使用。
构造方法
StringRedisTemplate提供了多种构造方法,通常开发者会通过配置Redis连接信息(如主机名、端口号等)来创建连接工厂,然后使用连接工厂来创建StringRedisTemplate实例。
常用操作方法
以下是一些常用的操作方法示例:

设置值:通过opsForValue().set(String key, String value)方法可以设置键值对。
获取值:通过opsForValue().get(String key)方法可以根据键获取对应的值。
删除值:通过delete(String key)方法可以删除指定的键值对。
追加字符串:通过opsForValue().append(String key, String value)方法可以向指定的键对应的字符串值的末尾追加值。
自增自减:通过opsForValue().increment(String key)和opsForValue().decrement(String key)方法可以实现字符串类型数据的自增和自减操作。
设置过期时间:在设置值时,可以指定过期时间,如opsForValue().set(String key, String value, long timeout, TimeUnit unit)方法。
注意事项
在使用StringRedisTemplate时,需要注意Redis服务器的连接信息配置,包括主机名、端口号、密码等。
对于数据类型为String的Redis操作,StringRedisTemplate提供了非常便捷的方法,但对于其他类型的数据(如Hash、List、Set等),则可能需要使用RedisTemplate或其他工具类进行操作。
在进行大量数据操作时,需要注意Redis的性能和内存使用情况,避免造成不必要的性能瓶颈或内存溢出等问题。

StringRedisTemplate 类源码

继承结构
在这里插入图片描述

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package org.springframework.data.redis.core;

import org.springframework.data.redis.connection.DefaultStringRedisConnection;
import org.springframework.data.redis.connection.RedisConnection;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.serializer.RedisSerializer;

public class StringRedisTemplate extends RedisTemplate<String, String> {
    public StringRedisTemplate() {
        this.setKeySerializer(RedisSerializer.string());
        this.setValueSerializer(RedisSerializer.string());
        this.setHashKeySerializer(RedisSerializer.string());
        this.setHashValueSerializer(RedisSerializer.string());
    }

    public StringRedisTemplate(RedisConnectionFactory connectionFactory) {
        this();
        this.setConnectionFactory(connectionFactory);
        this.afterPropertiesSet();
    }

    protected RedisConnection preProcessConnection(RedisConnection connection, boolean existingConnection) {
        return new DefaultStringRedisConnection(connection);
    }
}

源码分析:
StringRedisTemplate 继承自 RedisTemplate<String, String>,这意味着它是一个泛型类,其中键(Key)和值(Value)的类型都限定为 String。

StringRedisTemplate()这个构造函数通过调用 setKeySerializer、setValueSerializer、setHashKeySerializer 和 setHashValueSerializer 方法,将键、值、哈希键和哈希值的序列化器都设置为 RedisSerializer.string()。这意味着所有的键和值在存入 Redis 之前都会被转换成字符串,从 Redis 取出时也会从字符串转换回原来的类型(在这个场景下,由于本身就是字符串,所以实际上不需要转换)。

三:StringRedisTemplate和RedisTemplate区别在哪里

StringRedisTemplate和RedisTemplate在Spring框架中都是用于操作Redis数据库的模板类,但它们之间存在一些明显的区别,主要体现在以下几个方面:

1. 序列化策略

  • StringRedisTemplate:采用的是String的序列化策略,即它将Java对象序列化为字符串形式存储在Redis中,同时也将Redis中的字符串反序列化为Java对象。这种方式简化了操作,因为字符串是Redis中最基本的数据类型,支持的操作简单高效。
  • RedisTemplate:默认采用的是JDK的序列化策略(JdkSerializationRedisSerializer),即它将Java对象序列化为字节数组存储在Redis中。这种方式虽然可以处理任意类型的Java对象,但在Redis-cli中查看时可能会显示为乱码。不过,RedisTemplate的序列化策略是可以自定义的,常用的还有Jackson2JsonRedisSerializer等,可以将对象序列化为JSON字符串存储在Redis中。

2. 存储数据类型

  • StringRedisTemplate:专注于处理Redis中的String类型数据,提供了一系列简化操作String类型数据的方法。
  • RedisTemplate:是一个泛型类,可以对Redis中的任意类型数据进行操作,包括但不限于String、Hash、List、Set和Sorted Set等。它提供了丰富的API来支持这些数据类型的操作。

3. 使用范围

  • StringRedisTemplate:由于其专注于String类型数据,因此适用于存储简单的键值对、缓存数据、计数器等场景。
  • RedisTemplate:由于其泛型特性和丰富的API,适用于需要存储复杂对象或进行复杂查询的场景。如果你需要存取复杂的对象,并且不想做额外的处理,那么RedisTemplate可能是一个更好的选择。

4. 继承关系

  • StringRedisTemplate:实际上是RedisTemplate的一个子类,它在继承RedisTemplate的基础上,将泛型类型指定为了String,从而限制了其只能处理String类型的键值对。

5. 示例

假设我们有一个User对象需要存储到Redis中:

  • 使用StringRedisTemplate时,如果直接尝试存储User对象,会报错,因为StringRedisTemplate的set方法只接受String类型的键和值。我们需要先将User对象转换为String(例如通过JSON序列化),然后再存储。
  • 使用RedisTemplate时,如果采用默认的JDK序列化策略,可以直接存储User对象,但在Redis-cli中查看时会是乱码。如果采用JSON序列化策略(如Jackson2JsonRedisSerializer),则可以将User对象序列化为JSON字符串后存储,这样在Redis-cli中查看时会是可读的JSON字符串。

综上所述,StringRedisTemplate和RedisTemplate在序列化策略、存储数据类型、使用范围、继承关系等方面存在明显的区别。在选择使用哪个模板类时,需要根据具体的应用场景和需求来决定。

四:RedisTemplate源码

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperations<K, V>, BeanClassLoaderAware {
    private boolean enableTransactionSupport = false;
    private boolean exposeConnection = false;
    private boolean initialized = false;
    private boolean enableDefaultSerializer = true;
    @Nullable
    private RedisSerializer<?> defaultSerializer;
    @Nullable
    private ClassLoader classLoader;
    @Nullable
    private RedisSerializer keySerializer = null;
    @Nullable
    private RedisSerializer valueSerializer = null;
    @Nullable
    private RedisSerializer hashKeySerializer = null;
    @Nullable
    private RedisSerializer hashValueSerializer = null;
    private RedisSerializer<String> stringSerializer = RedisSerializer.string();
    @Nullable
    private ScriptExecutor<K> scriptExecutor;
    private final BoundOperationsProxyFactory boundOperations = new BoundOperationsProxyFactory();
    private final ValueOperations<K, V> valueOps = new DefaultValueOperations(this);
    private final ListOperations<K, V> listOps = new DefaultListOperations(this);
    private final SetOperations<K, V> setOps = new DefaultSetOperations(this);
    private final StreamOperations<K, ?, ?> streamOps = new DefaultStreamOperations(this, ObjectHashMapper.getSharedInstance());
    private final ZSetOperations<K, V> zSetOps = new DefaultZSetOperations(this);
    private final GeoOperations<K, V> geoOps = new DefaultGeoOperations(this);
    private final HyperLogLogOperations<K, V> hllOps = new DefaultHyperLogLogOperations(this);
    private final ClusterOperations<K, V> clusterOps = new DefaultClusterOperations(this);

    public RedisTemplate() {
    }

    public void afterPropertiesSet() {
        super.afterPropertiesSet();
        if (this.defaultSerializer == null) {
            this.defaultSerializer = new JdkSerializationRedisSerializer(this.classLoader != null ? this.classLoader : this.getClass().getClassLoader());
        }

        if (this.enableDefaultSerializer) {
            if (this.keySerializer == null) {
                this.keySerializer = this.defaultSerializer;
            }

            if (this.valueSerializer == null) {
                this.valueSerializer = this.defaultSerializer;
            }

            if (this.hashKeySerializer == null) {
                this.hashKeySerializer = this.defaultSerializer;
            }

            if (this.hashValueSerializer == null) {
                this.hashValueSerializer = this.defaultSerializer;
            }
        }

        if (this.scriptExecutor == null) {
            this.scriptExecutor = new DefaultScriptExecutor(this);
        }

        this.initialized = true;
    }

    public boolean isExposeConnection() {
        return this.exposeConnection;
    }

    public void setExposeConnection(boolean exposeConnection) {
        this.exposeConnection = exposeConnection;
    }

    public boolean isEnableDefaultSerializer() {
        return this.enableDefaultSerializer;
    }

    public void setEnableDefaultSerializer(boolean enableDefaultSerializer) {
        this.enableDefaultSerializer = enableDefaultSerializer;
    }

    public void setEnableTransactionSupport(boolean enableTransactionSupport) {
        this.enableTransactionSupport = enableTransactionSupport;
    }

    public void setBeanClassLoader(ClassLoader classLoader) {
        this.classLoader = classLoader;
    }

    @Nullable
    public RedisSerializer<?> getDefaultSerializer() {
        return this.defaultSerializer;
    }

    public void setDefaultSerializer(RedisSerializer<?> serializer) {
        this.defaultSerializer = serializer;
    }

    public void setKeySerializer(RedisSerializer<?> serializer) {
        this.keySerializer = serializer;
    }

    public RedisSerializer<?> getKeySerializer() {
        return this.keySerializer;
    }

    public void setValueSerializer(RedisSerializer<?> serializer) {
        this.valueSerializer = serializer;
    }

    public RedisSerializer<?> getValueSerializer() {
        return this.valueSerializer;
    }

    public RedisSerializer<?> getHashKeySerializer() {
        return this.hashKeySerializer;
    }

    public void setHashKeySerializer(RedisSerializer<?> hashKeySerializer) {
        this.hashKeySerializer = hashKeySerializer;
    }

    public RedisSerializer<?> getHashValueSerializer() {
        return this.hashValueSerializer;
    }

    public void setHashValueSerializer(RedisSerializer<?> hashValueSerializer) {
        this.hashValueSerializer = hashValueSerializer;
    }

    public RedisSerializer<String> getStringSerializer() {
        return this.stringSerializer;
    }

    public void setStringSerializer(RedisSerializer<String> stringSerializer) {
        this.stringSerializer = stringSerializer;
    }

    public void setScriptExecutor(ScriptExecutor<K> scriptExecutor) {
        this.scriptExecutor = scriptExecutor;
    }

    @Nullable
    public <T> T execute(RedisCallback<T> action) {
        return this.execute(action, this.isExposeConnection());
    }

    @Nullable
    public <T> T execute(RedisCallback<T> action, boolean exposeConnection) {
        return this.execute(action, exposeConnection, false);
    }

    @Nullable
    public <T> T execute(RedisCallback<T> action, boolean exposeConnection, boolean pipeline) {
        Assert.isTrue(this.initialized, "template not initialized; call afterPropertiesSet() before using it");
        Assert.notNull(action, "Callback object must not be null");
        RedisConnectionFactory factory = this.getRequiredConnectionFactory();
        RedisConnection conn = RedisConnectionUtils.getConnection(factory, this.enableTransactionSupport);

        Object var11;
        try {
            boolean existingConnection = TransactionSynchronizationManager.hasResource(factory);
            RedisConnection connToUse = this.preProcessConnection(conn, existingConnection);
            boolean pipelineStatus = connToUse.isPipelined();
            if (pipeline && !pipelineStatus) {
                connToUse.openPipeline();
            }

            RedisConnection connToExpose = exposeConnection ? connToUse : this.createRedisConnectionProxy(connToUse);
            T result = action.doInRedis(connToExpose);
            if (pipeline && !pipelineStatus) {
                connToUse.closePipeline();
            }

            var11 = this.postProcessResult(result, connToUse, existingConnection);
        } finally {
            RedisConnectionUtils.releaseConnection(conn, factory);
        }

        return var11;
    }

    public <T> T execute(SessionCallback<T> session) {
        Assert.isTrue(this.initialized, "template not initialized; call afterPropertiesSet() before using it");
        Assert.notNull(session, "Callback object must not be null");
        RedisConnectionFactory factory = this.getRequiredConnectionFactory();
        RedisConnectionUtils.bindConnection(factory, this.enableTransactionSupport);

        Object var3;
        try {
            var3 = session.execute(this);
        } finally {
            RedisConnectionUtils.unbindConnection(factory);
        }

        return var3;
    }

    public List<Object> executePipelined(SessionCallback<?> session) {
        return this.executePipelined(session, this.valueSerializer);
    }

    public List<Object> executePipelined(SessionCallback<?> session, @Nullable RedisSerializer<?> resultSerializer) {
        Assert.isTrue(this.initialized, "template not initialized; call afterPropertiesSet() before using it");
        Assert.notNull(session, "Callback object must not be null");
        RedisConnectionFactory factory = this.getRequiredConnectionFactory();
        RedisConnectionUtils.bindConnection(factory, this.enableTransactionSupport);

        List var4;
        try {
            var4 = (List)this.execute((connection) -> {
                connection.openPipeline();
                boolean pipelinedClosed = false;

                List var7;
                try {
                    Object result = this.executeSession(session);
                    if (result != null) {
                        throw new InvalidDataAccessApiUsageException("Callback cannot return a non-null value as it gets overwritten by the pipeline");
                    }

                    List<Object> closePipeline = connection.closePipeline();
                    pipelinedClosed = true;
                    var7 = this.deserializeMixedResults(closePipeline, resultSerializer, this.hashKeySerializer, this.hashValueSerializer);
                } finally {
                    if (!pipelinedClosed) {
                        connection.closePipeline();
                    }

                }

                return var7;
            });
        } finally {
            RedisConnectionUtils.unbindConnection(factory);
        }

        return var4;
    }

    public List<Object> executePipelined(RedisCallback<?> action) {
        return this.executePipelined(action, this.valueSerializer);
    }

    public List<Object> executePipelined(RedisCallback<?> action, @Nullable RedisSerializer<?> resultSerializer) {
        return (List)this.execute((connection) -> {
            connection.openPipeline();
            boolean pipelinedClosed = false;

            List var7;
            try {
                Object result = action.doInRedis(connection);
                if (result != null) {
                    throw new InvalidDataAccessApiUsageException("Callback cannot return a non-null value as it gets overwritten by the pipeline");
                }

                List<Object> closePipeline = connection.closePipeline();
                pipelinedClosed = true;
                var7 = this.deserializeMixedResults(closePipeline, resultSerializer, this.hashKeySerializer, this.hashValueSerializer);
            } finally {
                if (!pipelinedClosed) {
                    connection.closePipeline();
                }

            }

            return var7;
        });
    }

    public <T> T execute(RedisScript<T> script, List<K> keys, Object... args) {
        return this.scriptExecutor.execute(script, keys, args);
    }

    public <T> T execute(RedisScript<T> script, RedisSerializer<?> argsSerializer, RedisSerializer<T> resultSerializer, List<K> keys, Object... args) {
        return this.scriptExecutor.execute(script, argsSerializer, resultSerializer, keys, args);
    }

    public <T extends Closeable> T executeWithStickyConnection(RedisCallback<T> callback) {
        Assert.isTrue(this.initialized, "template not initialized; call afterPropertiesSet() before using it");
        Assert.notNull(callback, "Callback object must not be null");
        RedisConnectionFactory factory = this.getRequiredConnectionFactory();
        RedisConnection connection = this.preProcessConnection(RedisConnectionUtils.doGetConnection(factory, true, false, false), false);
        return (Closeable)callback.doInRedis(connection);
    }

    private Object executeSession(SessionCallback<?> session) {
        return session.execute(this);
    }

    protected RedisConnection createRedisConnectionProxy(RedisConnection connection) {
        Class<?>[] ifcs = ClassUtils.getAllInterfacesForClass(connection.getClass(), this.getClass().getClassLoader());
        return (RedisConnection)Proxy.newProxyInstance(connection.getClass().getClassLoader(), ifcs, new CloseSuppressingInvocationHandler(connection));
    }

    protected RedisConnection preProcessConnection(RedisConnection connection, boolean existingConnection) {
        return connection;
    }

    @Nullable
    protected <T> T postProcessResult(@Nullable T result, RedisConnection conn, boolean existingConnection) {
        return result;
    }

    public Boolean copy(K source, K target, boolean replace) {
        byte[] sourceKey = this.rawKey(source);
        byte[] targetKey = this.rawKey(target);
        return (Boolean)this.doWithKeys((connection) -> {
            return connection.copy(sourceKey, targetKey, replace);
        });
    }

    public Boolean hasKey(K key) {
        byte[] rawKey = this.rawKey(key);
        return (Boolean)this.doWithKeys((connection) -> {
            return connection.exists(rawKey);
        });
    }

    public Long countExistingKeys(Collection<K> keys) {
        Assert.notNull(keys, "Keys must not be null");
        byte[][] rawKeys = this.rawKeys(keys);
        return (Long)this.doWithKeys((connection) -> {
            return connection.exists(rawKeys);
        });
    }

    public Boolean delete(K key) {
        byte[] rawKey = this.rawKey(key);
        Long result = (Long)this.doWithKeys((connection) -> {
            return connection.del(new byte[][]{rawKey});
        });
        return result != null && result.intValue() == 1;
    }

    public Long delete(Collection<K> keys) {
        if (CollectionUtils.isEmpty(keys)) {
            return 0L;
        } else {
            byte[][] rawKeys = this.rawKeys(keys);
            return (Long)this.doWithKeys((connection) -> {
                return connection.del(rawKeys);
            });
        }
    }

    public Boolean unlink(K key) {
        byte[] rawKey = this.rawKey(key);
        Long result = (Long)this.doWithKeys((connection) -> {
            return connection.unlink(new byte[][]{rawKey});
        });
        return result != null && result.intValue() == 1;
    }

    public Long unlink(Collection<K> keys) {
        if (CollectionUtils.isEmpty(keys)) {
            return 0L;
        } else {
            byte[][] rawKeys = this.rawKeys(keys);
            return (Long)this.doWithKeys((connection) -> {
                return connection.unlink(rawKeys);
            });
        }
    }

    public DataType type(K key) {
        byte[] rawKey = this.rawKey(key);
        return (DataType)this.doWithKeys((connection) -> {
            return connection.type(rawKey);
        });
    }

    public Set<K> keys(K pattern) {
        byte[] rawKey = this.rawKey(pattern);
        Set<byte[]> rawKeys = (Set)this.doWithKeys((connection) -> {
            return connection.keys(rawKey);
        });
        return this.keySerializer != null ? SerializationUtils.deserialize(rawKeys, this.keySerializer) : rawKeys;
    }

    public Cursor<K> scan(ScanOptions options) {
        Assert.notNull(options, "ScanOptions must not be null");
        return (Cursor)this.executeWithStickyConnection((connection) -> {
            return new ConvertingCursor(connection.scan(options), this::deserializeKey);
        });
    }

    public K randomKey() {
        byte[] rawKey = (byte[])this.doWithKeys(RedisKeyCommands::randomKey);
        return this.deserializeKey(rawKey);
    }

    public void rename(K oldKey, K newKey) {
        byte[] rawOldKey = this.rawKey(oldKey);
        byte[] rawNewKey = this.rawKey(newKey);
        this.doWithKeys((connection) -> {
            connection.rename(rawOldKey, rawNewKey);
            return null;
        });
    }

    public Boolean renameIfAbsent(K oldKey, K newKey) {
        byte[] rawOldKey = this.rawKey(oldKey);
        byte[] rawNewKey = this.rawKey(newKey);
        return (Boolean)this.doWithKeys((connection) -> {
            return connection.renameNX(rawOldKey, rawNewKey);
        });
    }

    public Boolean expire(K key, final long timeout, final TimeUnit unit) {
        byte[] rawKey = this.rawKey(key);
        long rawTimeout = TimeoutUtils.toMillis(timeout, unit);
        return (Boolean)this.doWithKeys((connection) -> {
            try {
                return connection.pExpire(rawKey, rawTimeout);
            } catch (Exception var8) {
                return connection.expire(rawKey, TimeoutUtils.toSeconds(timeout, unit));
            }
        });
    }

    public Boolean expireAt(K key, final Date date) {
        byte[] rawKey = this.rawKey(key);
        return (Boolean)this.doWithKeys((connection) -> {
            try {
                return connection.pExpireAt(rawKey, date.getTime());
            } catch (Exception var4) {
                return connection.expireAt(rawKey, date.getTime() / 1000L);
            }
        });
    }

    public Boolean persist(K key) {
        byte[] rawKey = this.rawKey(key);
        return (Boolean)this.doWithKeys((connection) -> {
            return connection.persist(rawKey);
        });
    }

    public Long getExpire(K key) {
        byte[] rawKey = this.rawKey(key);
        return (Long)this.doWithKeys((connection) -> {
            return connection.ttl(rawKey);
        });
    }

    public Long getExpire(K key, TimeUnit timeUnit) {
        byte[] rawKey = this.rawKey(key);
        return (Long)this.doWithKeys((connection) -> {
            try {
                return connection.pTtl(rawKey, timeUnit);
            } catch (Exception var4) {
                return connection.ttl(rawKey, timeUnit);
            }
        });
    }

    public Boolean move(K key, final int dbIndex) {
        byte[] rawKey = this.rawKey(key);
        return (Boolean)this.doWithKeys((connection) -> {
            return connection.move(rawKey, dbIndex);
        });
    }

    public byte[] dump(K key) {
        byte[] rawKey = this.rawKey(key);
        return (byte[])this.doWithKeys((connection) -> {
            return connection.dump(rawKey);
        });
    }

    public void restore(K key, byte[] value, long timeToLive, TimeUnit unit, boolean replace) {
        byte[] rawKey = this.rawKey(key);
        long rawTimeout = TimeoutUtils.toMillis(timeToLive, unit);
        this.doWithKeys((connection) -> {
            connection.restore(rawKey, rawTimeout, value, replace);
            return null;
        });
    }

    @Nullable
    private <T> T doWithKeys(Function<RedisKeyCommands, T> action) {
        return this.execute((connection) -> {
            return action.apply(connection.keyCommands());
        }, true);
    }

    public List<V> sort(SortQuery<K> query) {
        return this.sort(query, this.valueSerializer);
    }

    public <T> List<T> sort(SortQuery<K> query, @Nullable RedisSerializer<T> resultSerializer) {
        byte[] rawKey = this.rawKey(query.getKey());
        SortParameters params = QueryUtils.convertQuery(query, this.stringSerializer);
        List<byte[]> vals = (List)this.doWithKeys((connection) -> {
            return connection.sort(rawKey, params);
        });
        return SerializationUtils.deserialize(vals, resultSerializer);
    }

    public <T> List<T> sort(SortQuery<K> query, BulkMapper<T, V> bulkMapper) {
        return this.sort(query, bulkMapper, this.valueSerializer);
    }

    public <T, S> List<T> sort(SortQuery<K> query, BulkMapper<T, S> bulkMapper, @Nullable RedisSerializer<S> resultSerializer) {
        List<S> values = this.sort(query, resultSerializer);
        if (values != null && !values.isEmpty()) {
            int bulkSize = query.getGetPattern().size();
            List<T> result = new ArrayList(values.size() / bulkSize + 1);
            List<S> bulk = new ArrayList(bulkSize);
            Iterator var8 = values.iterator();

            while(var8.hasNext()) {
                S s = var8.next();
                bulk.add(s);
                if (bulk.size() == bulkSize) {
                    result.add(bulkMapper.mapBulk(Collections.unmodifiableList(bulk)));
                    bulk = new ArrayList(bulkSize);
                }
            }

            return result;
        } else {
            return Collections.emptyList();
        }
    }

    public Long sort(SortQuery<K> query, K storeKey) {
        byte[] rawStoreKey = this.rawKey(storeKey);
        byte[] rawKey = this.rawKey(query.getKey());
        SortParameters params = QueryUtils.convertQuery(query, this.stringSerializer);
        return (Long)this.doWithKeys((connection) -> {
            return connection.sort(rawKey, params, rawStoreKey);
        });
    }

    public void watch(K key) {
        byte[] rawKey = this.rawKey(key);
        this.executeWithoutResult((connection) -> {
            connection.watch(new byte[][]{rawKey});
        });
    }

    public void watch(Collection<K> keys) {
        byte[][] rawKeys = this.rawKeys(keys);
        this.executeWithoutResult((connection) -> {
            connection.watch(rawKeys);
        });
    }

    public void unwatch() {
        this.executeWithoutResult(RedisTxCommands::unwatch);
    }

    public void multi() {
        this.executeWithoutResult(RedisTxCommands::multi);
    }

    public void discard() {
        this.executeWithoutResult(RedisTxCommands::discard);
    }

    public List<Object> exec() {
        List<Object> results = this.execRaw();
        return this.getRequiredConnectionFactory().getConvertPipelineAndTxResults() ? this.deserializeMixedResults(results, this.valueSerializer, this.hashKeySerializer, this.hashValueSerializer) : results;
    }

    public List<Object> exec(RedisSerializer<?> valueSerializer) {
        return this.deserializeMixedResults(this.execRaw(), valueSerializer, valueSerializer, valueSerializer);
    }

    protected List<Object> execRaw() {
        List<Object> raw = (List)this.execute(RedisTxCommands::exec);
        return raw == null ? Collections.emptyList() : raw;
    }

    public List<RedisClientInfo> getClientList() {
        return (List)this.execute(RedisServerCommands::getClientList);
    }

    public void killClient(String host, int port) {
        this.executeWithoutResult((connection) -> {
            connection.killClient(host, port);
        });
    }

    public void replicaOf(String host, int port) {
        this.executeWithoutResult((connection) -> {
            connection.replicaOf(host, port);
        });
    }

    public void replicaOfNoOne() {
        this.executeWithoutResult(RedisServerCommands::replicaOfNoOne);
    }

    public Long convertAndSend(String channel, Object message) {
        Assert.hasText(channel, "a non-empty channel is required");
        byte[] rawChannel = this.rawString(channel);
        byte[] rawMessage = this.rawValue(message);
        return (Long)this.execute((connection) -> {
            return connection.publish(rawChannel, rawMessage);
        }, true);
    }

    private void executeWithoutResult(Consumer<RedisConnection> action) {
        this.execute((it) -> {
            action.accept(it);
            return null;
        }, true);
    }

    public ClusterOperations<K, V> opsForCluster() {
        return this.clusterOps;
    }

    public GeoOperations<K, V> opsForGeo() {
        return this.geoOps;
    }

    public BoundGeoOperations<K, V> boundGeoOps(K key) {
        return (BoundGeoOperations)this.boundOperations.createProxy(BoundGeoOperations.class, key, DataType.ZSET, this, RedisOperations::opsForGeo);
    }

    public <HK, HV> BoundHashOperations<K, HK, HV> boundHashOps(K key) {
        return (BoundHashOperations)this.boundOperations.createProxy(BoundHashOperations.class, key, DataType.HASH, this, (it) -> {
            return it.opsForHash();
        });
    }

    public <HK, HV> HashOperations<K, HK, HV> opsForHash() {
        return new DefaultHashOperations(this);
    }

    public HyperLogLogOperations<K, V> opsForHyperLogLog() {
        return this.hllOps;
    }

    public ListOperations<K, V> opsForList() {
        return this.listOps;
    }

    public BoundListOperations<K, V> boundListOps(K key) {
        return (BoundListOperations)this.boundOperations.createProxy(BoundListOperations.class, key, DataType.LIST, this, RedisOperations::opsForList);
    }

    public BoundSetOperations<K, V> boundSetOps(K key) {
        return (BoundSetOperations)this.boundOperations.createProxy(BoundSetOperations.class, key, DataType.SET, this, RedisOperations::opsForSet);
    }

    public SetOperations<K, V> opsForSet() {
        return this.setOps;
    }

    public <HK, HV> StreamOperations<K, HK, HV> opsForStream() {
        return this.streamOps;
    }

    public <HK, HV> StreamOperations<K, HK, HV> opsForStream(HashMapper<? super K, ? super HK, ? super HV> hashMapper) {
        return new DefaultStreamOperations(this, hashMapper);
    }

    public <HK, HV> BoundStreamOperations<K, HK, HV> boundStreamOps(K key) {
        return (BoundStreamOperations)this.boundOperations.createProxy(BoundStreamOperations.class, key, DataType.STREAM, this, (it) -> {
            return this.opsForStream();
        });
    }

    public BoundValueOperations<K, V> boundValueOps(K key) {
        return (BoundValueOperations)this.boundOperations.createProxy(BoundValueOperations.class, key, DataType.STRING, this, RedisOperations::opsForValue);
    }

    public ValueOperations<K, V> opsForValue() {
        return this.valueOps;
    }

    public BoundZSetOperations<K, V> boundZSetOps(K key) {
        return (BoundZSetOperations)this.boundOperations.createProxy(BoundZSetOperations.class, key, DataType.ZSET, this, RedisOperations::opsForZSet);
    }

    public ZSetOperations<K, V> opsForZSet() {
        return this.zSetOps;
    }

    private byte[] rawKey(Object key) {
        Assert.notNull(key, "non null key required");
        if (this.keySerializer == null && key instanceof byte[] bytes) {
            return bytes;
        } else {
            return this.keySerializer.serialize(key);
        }
    }

    private byte[] rawString(String key) {
        return this.stringSerializer.serialize(key);
    }

    private byte[] rawValue(Object value) {
        if (this.valueSerializer == null && value instanceof byte[] bytes) {
            return bytes;
        } else {
            return this.valueSerializer.serialize(value);
        }
    }

    private byte[][] rawKeys(Collection<K> keys) {
        byte[][] rawKeys = new byte[keys.size()][];
        int i = 0;

        Object key;
        for(Iterator var4 = keys.iterator(); var4.hasNext(); rawKeys[i++] = this.rawKey(key)) {
            key = var4.next();
        }

        return rawKeys;
    }

    private K deserializeKey(byte[] value) {
        return this.keySerializer != null ? this.keySerializer.deserialize(value) : value;
    }

    @Nullable
    private List<Object> deserializeMixedResults(@Nullable List<Object> rawValues, @Nullable RedisSerializer valueSerializer, @Nullable RedisSerializer hashKeySerializer, @Nullable RedisSerializer hashValueSerializer) {
        if (rawValues == null) {
            return null;
        } else {
            List<Object> values = new ArrayList();
            Iterator var6 = rawValues.iterator();

            while(true) {
                while(var6.hasNext()) {
                    Object rawValue = var6.next();
                    if (rawValue instanceof byte[]) {
                        byte[] bytes = (byte[])rawValue;
                        if (valueSerializer != null) {
                            values.add(valueSerializer.deserialize(bytes));
                            continue;
                        }
                    }

                    if (rawValue instanceof List) {
                        List list = (List)rawValue;
                        values.add(this.deserializeMixedResults(list, valueSerializer, hashKeySerializer, hashValueSerializer));
                    } else {
                        if (rawValue instanceof Set) {
                            Set set = (Set)rawValue;
                            if (!set.isEmpty()) {
                                values.add(this.deserializeSet(set, valueSerializer));
                                continue;
                            }
                        }

                        if (rawValue instanceof Map) {
                            Map map = (Map)rawValue;
                            if (!map.isEmpty() && map.values().iterator().next() instanceof byte[]) {
                                values.add(SerializationUtils.deserialize(map, hashKeySerializer, hashValueSerializer));
                                continue;
                            }
                        }

                        values.add(rawValue);
                    }
                }

                return values;
            }
        }
    }

    private Set<?> deserializeSet(Set rawSet, @Nullable RedisSerializer valueSerializer) {
        if (rawSet.isEmpty()) {
            return rawSet;
        } else {
            Object setValue = rawSet.iterator().next();
            if (setValue instanceof byte[] && valueSerializer != null) {
                return SerializationUtils.deserialize(rawSet, valueSerializer);
            } else {
                return setValue instanceof Tuple ? this.convertTupleValues(rawSet, valueSerializer) : rawSet;
            }
        }
    }

    private Set<ZSetOperations.TypedTuple<V>> convertTupleValues(Set<Tuple> rawValues, @Nullable RedisSerializer valueSerializer) {
        Set<ZSetOperations.TypedTuple<V>> set = new LinkedHashSet(rawValues.size());

        Tuple rawValue;
        Object value;
        for(Iterator var4 = rawValues.iterator(); var4.hasNext(); set.add(new DefaultTypedTuple(value, rawValue.getScore()))) {
            rawValue = (Tuple)var4.next();
            value = rawValue.getValue();
            if (valueSerializer != null) {
                value = valueSerializer.deserialize(rawValue.getValue());
            }
        }

        return set;
    }
}

继承结构
在这里插入图片描述
很明显StringRedisTemplate和RedisTemplate是父类和子类关系。

在上面源码里看到,StringRedisTemplate并无重写RedisTemplate的任何方法。所以拥有RedisTemplate的所有方法。

五:StringRedisTemplate的主要方法有哪些?怎么设置缓存过期时间?

StringRedisTemplate是Spring Framework提供的一个用于操作Redis数据库中String类型数据的模板类。它基于RedisTemplate实现,并专注于处理Redis中的String类型数据,提供了一系列简化操作的方法。以下是StringRedisTemplate的一些常用方法讲解:

1. 字符串操作

设置和获取值
  • opsForValue().set(String key, String value):向Redis中存入一个字符串类型的键值对。
  • opsForValue().get(Object key):根据键获取对应的值。
设置带有过期时间的值
  • opsForValue().set(String key, String value, long timeout, TimeUnit unit):向Redis中存入一个字符串类型的键值对,并设置过期时间。timeout是过期时长,unit是时间单位(如秒、分钟等)。
递增和递减
  • opsForValue().increment(String key):将存储在键中的数字值增加1。
  • opsForValue().increment(String key, long delta):将存储在键中的数字值增加指定的增量值delta
  • opsForValue().decrement(String key)opsForValue().decrement(String key, long delta):与递增操作类似,但用于减少数字值。

2. 哈希操作

  • opsForHash().put(String key, Object hashKey, Object value):向哈希表中添加一个字段。
  • opsForHash().entries(String key):获取存储在哈希表中指定键的所有字段和值。

3. 列表操作

  • opsForList().leftPush(String key, String value):将一个或多个值插入到列表头部。
  • opsForList().rightPush(String key, String value):将一个或多个值插入到列表尾部。
  • opsForList().range(String key, long start, long end):通过索引区间返回列表中的一部分元素。

4. 集合操作

  • opsForSet().add(String key, String... values):向集合添加一个或多个成员。
  • opsForSet().members(String key):返回集合中的所有成员。

5. 有序集合操作

  • opsForZSet().add(String key, double score, String value):将一个或多个成员及其分数加入到有序集合中。
  • opsForZSet().range(String key, long start, long end):通过索引区间返回有序集合中指定区间的成员。

6. 其他常用方法

  • delete(String key, Object... keys):根据提供的键删除缓存中的数据。
  • hasKey(String key):检查键是否存在。
  • getExpire(String key, TimeUnit unit):获取键的剩余生存时间,并转换成指定的时间单位。

注意事项

  • 使用StringRedisTemplate时,通常不需要额外配置序列化器,因为它默认使用String序列化策略。但如果需要存储复杂对象,可能需要自定义序列化器。
  • StringRedisTemplate提供的方法非常丰富,这里只列举了一些常用方法。更多方法可以通过查看官方文档或源码来了解。

总的来说,StringRedisTemplate是Spring Data Redis中一个非常实用的工具类,它简化了Redis的操作,使开发者能够更轻松地将Redis集成到Spring应用程序中。

六:opsForSet()和opsForZSet()有什么区别?

opsForSet()opsForZSet()RedisTemplate类中提供的两个方法,它们分别用于操作Redis中的SET和ZSET(Sorted Set)数据结构。以下是这两个方法的主要区别:

1. 数据结构特性

  • opsForSet():用于操作SET数据结构。SET是一个无序的、不包含重复元素的字符串集合。SET中的元素没有特定的顺序,且每个元素都是唯一的。
  • opsForZSet():用于操作ZSET数据结构。ZSET是一个有序的、不包含重复元素的字符串集合,每个元素都会关联一个分数(score),Redis会根据这个分数对元素进行排序。

2. 支持的操作

  • opsForSet():支持的操作包括添加元素(SADD)、删除元素(SREM)、判断元素是否存在(SISMEMBER)、获取集合中的所有元素(SMEMBERS)、获取集合大小(SCARD)等。SET主要用于存储不需要排序的、唯一的元素集合。
  • opsForZSet():除了支持类似SET的添加(ZADD)、删除(ZREM)和查找(ZSCORE)操作外,还支持根据分数范围查询元素(ZRANGEBYSCORE、ZREVRANGEBYSCORE)、获取元素的排名(ZRANK、ZREVRANK)、计算分数范围内的元素数量(ZCOUNT)等高级功能。ZSET主要用于需要根据分数进行排序或统计的场景。

3. 排序与分数

  • opsForSet():由于SET是无序的,因此不支持根据任何特定顺序对元素进行排序或检索。
  • opsForZSet():ZSET中的元素会根据关联的分数进行排序。可以通过分数范围或排名来检索元素,这使得ZSET非常适合用于实现排行榜、评分系统等需要排序或统计的场景。

4. 性能考虑

  • opsForSet():由于SET是无序的,且每个元素都是唯一的,因此其操作时间复杂度一般为O(1),即常数时间复杂度,这使得它在处理大量数据时具有较高的效率。
  • opsForZSet():虽然ZSET提供了排序功能,但其操作时间复杂度一般为O(logN),其中N是集合中元素的数量。这意味着随着集合大小的增加,操作所需的时间也会相应增加,但仍然保持较高的效率。

综上所述,opsForSet()opsForZSet()的主要区别在于它们操作的数据结构特性、支持的操作、排序与分数以及性能考虑等方面。在选择使用哪个方法时,应根据实际需求进行权衡和选择。


原文地址:https://blog.csdn.net/qq_21004057/article/details/142384899

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