Redis在项目中的应用

在aop模式下使用redis 的方式

（1）添加依赖

<dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.3.2.RELEASE</version>
                <scope>import</scope>
                <type>pom</type>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

（2）配置文件中配置application.yml

spring:
  redis:
    host: 192.168.126.129  #写自己的ip
    port: 6379

(3)创建启动类，如果用注解方式需要在此处添加注解（@EnableCache）

package com.jt;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
//@EnableCache
@SpringBootApplication
public class RedisApplication {
    public static void main(String[] args) {
        SpringApplication.run(RedisApplication.class,args);
    }
}

（4）获取菜单基于restemplate（方式一）

package com.jt.service;
import com.jt.dao.MenuMapper;
import com.jt.pojo.Menu;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.time.Duration;

@Service
public class MenuServiceImpl implements MenuService{
    @Autowired
    private MenuMapper menuMapper;

   // @Autowired
   // private RedisTemplate redisTemplate;

    @Resource(name="redisTemplate")
    private ValueOperations valueOperations;//从spring.io官方的data项目中去查这种注入方式
    /**
     * 基于id查询菜单信息,要求:
     * 1)先查redis,redis没有去查mysql
     * 2)将从mysql查询到的数据存储到redis
     * @param id
     * @return
     */
    @Override
    public Menu selectById(Long id) {
        //ValueOperations valueOperations = redisTemplate.opsForValue();
        Object obj=valueOperations.get(String.valueOf(id));
        if(obj!=null){
            System.out.println("Get Data from redis");
            return (Menu)obj;
        }
        Menu menu=menuMapper.selectById(id);
        valueOperations.set(String.valueOf(id), menu, Duration.ofSeconds(120));
        return menu;
    }
    @Override
    public Menu insertMenu(Menu menu) {
        menuMapper.insert(menu);
       // ValueOperations valueOperations = redisTemplate.opsForValue();
        valueOperations.set(String.valueOf(menu.getId()), menu, Duration.ofSeconds(120));
        return menu;
    }
    @Override
    public Menu updateMenu(Menu menu) {
        menuMapper.updateById(menu);
       // ValueOperations valueOperations = redisTemplate.opsForValue();
        valueOperations.set(String.valueOf(menu.getId()), menu, Duration.ofSeconds(120));
        return menu;
    }
}

（5）获取菜单基于注解（AOP方式，方式二）

package com.jt.service;

import com.jt.dao.MenuMapper;
import com.jt.pojo.Menu;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

@Service
public class DefaultMenuService implements MenuService{
    @Autowired
    private MenuMapper menuMapper;

    /**
     * 由此注解描述的方法为切入点方法,此方法执行时,底层会通过AOP机制
     * 先从缓存取数据,缓存有则直接返回,缓存没有则查数据,最后将查询的数据
     * 还会向redis存储一份
     * @param id
     * @return
     */
    @Cacheable(value = "menuCache",key="#id")
    @Override
    public Menu selectById(Long id) {
        return menuMapper.selectById(id);
    }

    /**
     * CachePut注解的意思是更新缓存
     * @param menu
     * @return
     */
    @CachePut(value = "menuCache",key="#menu.id")
    @Override
    public Menu insertMenu(Menu menu) {
         menuMapper.insert(menu);
         return menu;
    }

    @CachePut(value = "menuCache",key="#menu.id")
    @Override
    public Menu updateMenu(Menu menu) {
        menuMapper.updateById(menu);
        return menu;
    }
}

（6）设置redis中的序列化格式

package com.jt;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.CachingConfigurerSupport;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
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.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.RedisSerializer;

/**
 * 重构CacheManager对象,其目的是改变AOP方式应用redis的序列化和反序列化的方式.
 */
@Configuration
public class CacheManagerConfig {
    /**
     * 重构CacheManager对象
     * @return
     */
    @Bean
    public CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {
        //定义RedisCache配置
        RedisCacheConfiguration cacheConfig=
                RedisCacheConfiguration.defaultCacheConfig()
        //定义key的序列化方式
        .serializeKeysWith(
                RedisSerializationContext.
                   SerializationPair.fromSerializer(RedisSerializer.string()))
        //定义value的序列化方式
        .serializeValuesWith(
                RedisSerializationContext.SerializationPair
                .fromSerializer(RedisSerializer.json()));

        return  RedisCacheManager.builder(redisConnectionFactory)
               .cacheDefaults(cacheConfig)
               .build();//建造者模式(复杂对象的创建,建议使用这种方式,封装了对象的创建细节)
    }
}