Redis大杂烩

Redis是一个键值对内存数据库，也支持持久化到磁盘

Redis的安装与启动

brew install redis 在macOS中安装Redis
redis-server 在前台启动Redis，监听6379端口

Redis在SpringBoot项目中的配置

添加依赖spring-boot-starter-data-redis即可

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

Java示例代码

package bj.redis;

import io.vavr.control.Try;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.data.redis.core.StringRedisTemplate;

import javax.annotation.Resource;
import javax.validation.constraints.NotNull;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

/**
 * Created by BaiJiFeiLong@gmail.com at 2018/12/13 上午9:51
 */
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class RedisApp implements ApplicationListener<ApplicationReadyEvent> {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    public static void main(String[] args) {
        SpringApplication.run(RedisApp.class, args);
    }

    @Override
    public void onApplicationEvent(@NotNull ApplicationReadyEvent event) {
        Try.run(this::_onReady).getOrElseThrow((Function<Throwable, RuntimeException>) RuntimeException::new);
    }

    private void _onReady() throws InterruptedException {
        stringRedisTemplate.opsForValue().set("GMail", "Google", 1, TimeUnit.SECONDS);
        System.out.println("[After cached] GMail: " + stringRedisTemplate.opsForValue().get("GMail"));
        Thread.sleep(1000);
        System.out.println("[After timeout] GMail: " + stringRedisTemplate.opsForValue().get("GMail"));
    }
}

控制台输出

.   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.0.RELEASE)

2018-12-13 10:15:58.921  INFO 44761 --- [           main] bj.redis.RedisApp                        : Starting RedisApp on MacBook-Air-2.local with PID 44761 (/Users/yuchao/temp/java/hellomaven/target/classes started by yuchao in /Users/yuchao/temp/java/hellomaven)
2018-12-13 10:15:58.936  INFO 44761 --- [           main] bj.redis.RedisApp                        : No active profile set, falling back to default profiles: default
2018-12-13 10:16:00.818  INFO 44761 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Multiple Spring Data modules found, entering strict repository configuration mode!
2018-12-13 10:16:00.821  INFO 44761 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data repositories in DEFAULT mode.
2018-12-13 10:16:00.859  INFO 44761 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 17ms. Found 0 repository interfaces.
2018-12-13 10:16:02.564  INFO 44761 --- [           main] bj.redis.RedisApp                        : Started RedisApp in 4.561 seconds (JVM running for 6.042)
2018-12-13 10:16:02.692  INFO 44761 --- [           main] io.lettuce.core.EpollProvider            : Starting without optional epoll library
2018-12-13 10:16:02.809  INFO 44761 --- [           main] io.lettuce.core.KqueueProvider           : Starting with kqueue library
[After cached] GMail: Google
[After timeout] GMail: null

Redis与SpringCache

示例代码

package bj.redis;

import io.vavr.collection.HashMap;
import io.vavr.control.Try;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.ApplicationListener;
import org.springframework.context.annotation.Bean;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import javax.validation.constraints.NotNull;
import java.time.Duration;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

/**
 * Created by BaiJiFeiLong@Gmail.com at 2018/12/13 上午9:51
 */
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
@EnableCaching
public class RedisApp implements ApplicationListener<ApplicationReadyEvent> {


    public static void main(String[] args) {
        SpringApplication.run(RedisApp.class, args);
    }

    @Override
    public void onApplicationEvent(@NotNull ApplicationReadyEvent event) {
        Try.run(this::_onReady).getOrElseThrow((Function<Throwable, RuntimeException>) RuntimeException::new);
    }

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private Inner inner;

    private void _onReady() throws InterruptedException {
        stringRedisTemplate.opsForValue().set("a", "b");
        System.out.println("TTL of a: " + stringRedisTemplate.getExpire("a", TimeUnit.MILLISECONDS));
        System.out.println("[Before cache] Owner of Gmail: " + inner.owner("Gmail"));
        System.out.println("[After cache] Owner of Gmail: " + inner.owner("Gmail"));
        System.out.println("Expire millis: " + stringRedisTemplate.getExpire("alpha::owner::Gmail", TimeUnit.MILLISECONDS));
        System.out.println("Keys: " + stringRedisTemplate.keys("*"));
        Thread.sleep(100);
        System.out.println("[After expire] Owner of Gmail: " + inner.owner("Gmail"));
        System.out.println("Raw: " + stringRedisTemplate.opsForValue().get("alpha::owner::Gmail"));
    }

    @Component
    static class Inner {
        @Cacheable("alpha::owner")
        public String owner(String product) {
            System.out.println("Fetching...");
            return HashMap.of("Gmail", "Google").getOrElse(product, null);
        }
    }

    @Bean
    public RedisCacheConfiguration redisCacheConfiguration() {
        return RedisCacheConfiguration.defaultCacheConfig()
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer()))
                .entryTtl(Duration.ofMillis(100));
    }
}

控制台输出

.   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.0.RELEASE)

2018-12-13 11:48:16.788  INFO 45720 --- [           main] bj.redis.RedisApp                        : Starting RedisApp on MacBook-Air-2.local with PID 45720 (/Users/yuchao/temp/java/hellomaven/target/classes started by yuchao in /Users/yuchao/temp/java/hellomaven)
2018-12-13 11:48:16.810  INFO 45720 --- [           main] bj.redis.RedisApp                        : No active profile set, falling back to default profiles: default
2018-12-13 11:48:18.079  INFO 45720 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Multiple Spring Data modules found, entering strict repository configuration mode!
2018-12-13 11:48:18.082  INFO 45720 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data repositories in DEFAULT mode.
2018-12-13 11:48:18.117  INFO 45720 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 16ms. Found 0 repository interfaces.
2018-12-13 11:48:19.243  INFO 45720 --- [           main] bj.redis.RedisApp                        : Started RedisApp in 3.305 seconds (JVM running for 4.684)
2018-12-13 11:48:19.484  INFO 45720 --- [           main] io.lettuce.core.EpollProvider            : Starting without optional epoll library
2018-12-13 11:48:19.512  INFO 45720 --- [           main] io.lettuce.core.KqueueProvider           : Starting with kqueue library
TTL of a: -1
Fetching...
[Before cache] Owner of Gmail: Google
[After cache] Owner of Gmail: Google
Expire millis: 54
Keys: [a, alpha::owner::Gmail]
Fetching...
[After expire] Owner of Gmail: Google
Raw: "Google"

要点

自定义Redis配置需要自定义org.springframework.data.redis.cache.RedisCacheConfiguration。自定义RedisTemplate不管用
RedisCacheConfiguration的配置不影响RedisTemplate和StringRedisTemplate的注入
SpringBoot2对缓存键的序列化默认使用字符串策略
SpringBoot2对缓存值的序列化默认使用字节码策略
serializeValuesWith 可以配置缓存值的序列化策略
entryTtl 可以配置Redis的全局缓存超时
stringRedisTemplate.keys("*")可以获取所有缓存键。不能使用redisTemplate
org.springframework.data.redis.core.RedisTemplate#getExpire(K, java.util.concurrent.TimeUnit) 获取缓存键超时时间
SpringCache默认对缓存键前缀以"缓存名称::"。可以通过org.springframework.data.redis.cache.RedisCacheConfiguration#prefixKeysWith进行自定义
Spring2的RedisCacheManager(org.springframework.data.redis.cache.RedisCacheManager)去掉了TTL相关逻辑。要想通过@Cacheable注解实现自定义缓存TTL，非常困难，应该得自定义org.springframework.data.redis.cache.RedisCacheWriter

RedisTemplate的创建与使用

示例Java代码

package bj.redis;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

import java.awt.*;

/**
 * Created by BaiJiFeiLong@gmail.com at 2018/12/26 下午8:04
 */
public class RedisApp2 {
    @SuppressWarnings("ConstantConditions")
    public static void main(String[] args) {
        ((Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME)).setLevel(Level.INFO);
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(new LettuceConnectionFactory() {{
            afterPropertiesSet();
        }});
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer());
        redisTemplate.afterPropertiesSet();
        redisTemplate.opsForValue().set("point", new Point(0, 1));

        System.out.printf("[Object] %s => %s\n", "point", redisTemplate.opsForValue().get("point"));
        String value = new String(redisTemplate.getConnectionFactory().getConnection().get("point".getBytes()));
        System.out.printf("[Raw] %s => %s\n", "point", value);
    }
}

示例输出

21:40:58.714 [main] INFO io.lettuce.core.EpollProvider - Starting without optional epoll library
21:40:58.801 [main] INFO io.lettuce.core.KqueueProvider - Starting with kqueue library
[Object] point => java.awt.Point[x=0,y=1]
[Raw] point => {"@class":"java.awt.Point","x":0.0,"y":1.0}

Redis大忌

KEYS命令生产环境万万要禁用KEYS命令，因为Redis对键名不建立Partial索引，KEYS命令时间复杂度为n

文章首发: https://baijifeilong.github.io