java连接redis

引入redis依赖---------->jedis

<dependency>
      <groupId>redis.clients</groupId>
      <artifactId>jedis</artifactId>
      <version>3.6.0</version>
</dependency>

java代码操控redis

public class TextRedis {
    public static void main(String[] args) {
        Jedis jedis=new Jedis("192.168.145.3",6379);
        jedis.set("k1","a");
        jedis.set("k2","b");
        jedis.set("k3","c");
        List<String> mget=jedis.mget("k1","k2");
        System.out.println(mget);
    }
}

Springboot整合redis。

依赖---->启动依赖--->自动装配--->自动读取装置

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

代码测试

连接redis，配置文件配置

连接集群

哨兵

集群

Springboot使用redis作为缓存

作用：为了减少对数据库的访问频率，从而提高项目的性能。

放入缓存中的数据一般都是查询频率高，修改概率低，数据安全行要求低的。

如何使用

序列化与反序列化

public User select(Long id){
    redisTemplate.setKeySerializer(new StringRedisSerializer());
    redisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer());
    ValueOperations valueOperations=redisTemplate.opsForValue();
    Object o=valueOperations.get("user::findById::"+id);
    if (o!=null){
        return (User) o;
    }
    User user=userMapper.selectById(id);
    if(user!=null){
        valueOperations.set("user::findById::"+id,user);
    }
    return user;
}

以上是基础写法，重复率较高

简便写法

使用缓存注解：在相应方法上加缓存注解则可以完成缓存的功能

1.添加缓存配置类

package com.example.demospringbootredis.cofig;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.cache.CacheManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

import java.time.Duration;

@Configuration
public class RedisConfig {
    //比如验证码
    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        RedisSerializer<String> redisSerializer = new StringRedisSerializer();
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);
        template.setConnectionFactory(factory);
        //key序列化方式
        template.setKeySerializer(redisSerializer);
        //value序列化
        template.setValueSerializer(jackson2JsonRedisSerializer);
        //value hashmap序列化
        template.setHashValueSerializer(jackson2JsonRedisSerializer);
        return template;
    }

    @Bean
    public CacheManager cacheManager(RedisConnectionFactory factory) {
        RedisSerializer<String> redisSerializer = new StringRedisSerializer();
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        //解决查询缓存转换异常的问题
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);
        // 配置序列化（解决乱码的问题）,过期时间600秒
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig()
                .entryTtl(Duration.ofSeconds(600)) //缓存过期10分钟 ---- 业务需求。
                .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(redisSerializer))//设置key的序列化方式
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(jackson2JsonRedisSerializer)) //设置value的序列化
                .disableCachingNullValues();
        RedisCacheManager cacheManager = RedisCacheManager.builder(factory)
                .cacheDefaults(config)
                .build();
        return cacheManager;
    }
}

2.在相应的方法上加上注解缓存

3.在主启动类上启动缓存注解