Spring Boot使用redis实现数据缓存

基于Spring Boot 1.5.2.RELEASE版本，一方面验证与Redis的集成方法，另外了解使用方法。

集成方法

1. 配置依赖

   修改pom.xml，增加如下内容。

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

2. 配置Redis

   修改application.yml，增加如下内容。

   spring:
       redis:
           host: localhost
           port: 6379
           pool:
               max-idle: 8
               min-idle: 0
               max-active: 8
               max-wait: -1

3. 配置Redis缓存

   
   package net.jackieathome.cache;
   
   import java.lang.reflect.Method;
   
   import org.springframework.cache.CacheManager;
   import org.springframework.cache.annotation.CachingConfigurerSupport;
   import org.springframework.cache.annotation.EnableCaching;
   import org.springframework.cache.interceptor.KeyGenerator;
   import org.springframework.context.annotation.Bean;
   import org.springframework.context.annotation.Configuration;
   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.core.StringRedisTemplate;
   import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
   
   import com.fasterxml.jackson.annotation.JsonAutoDetect;
   import com.fasterxml.jackson.annotation.PropertyAccessor;
   import com.fasterxml.jackson.databind.ObjectMapper;
   
   @Configuration
   @EnableCaching // 启用缓存特性
   public class RedisConfig extends CachingConfigurerSupport {
       // 缓存数据时Key的生成器，可以依据业务和技术场景自行定制
   //  @Bean
   //  public KeyGenerator customizedKeyGenerator() {
   //      return new KeyGenerator() {
   //          @Override
   //          public Object generate(Object target, Method method, Object... params) {
   //              StringBuilder sb = new StringBuilder();
   //              sb.append(target.getClass().getName());
   //              sb.append(method.getName());
   //              for (Object obj : params) {
   //                  sb.append(obj.toString());
   //              }
   //              return sb.toString();
   //          }
   //      };
   //
   //  }
       // 定制缓存管理器的属性，默认提供的CacheManager对象可能不能满足需要
       // 因此建议依赖业务和技术上的需求，自行做一些扩展和定制
       @Bean
       public CacheManager cacheManager(@SuppressWarnings("rawtypes") RedisTemplate redisTemplate) {
           RedisCacheManager redisCacheManager = new RedisCacheManager(redisTemplate);
           redisCacheManager.setDefaultExpiration(300);
           return redisCacheManager;
       }
   
       @Bean
       public RedisTemplate<String, String> redisTemplate(RedisConnectionFactory factory) {
           StringRedisTemplate template = new StringRedisTemplate(factory);
           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.setValueSerializer(jackson2JsonRedisSerializer);
           template.afterPropertiesSet();
           return template;
       }
   }

验证集成后的效果

考虑到未来参与的项目基于MyBatis实现数据库访问，而利用缓存，可有效改善Web页面的交互体验，因此设计了如下两个验证方案。

方案一

在访问数据库的数据对象上增加缓存注解，定义缓存策略。从测试效果看，缓存有效。

1. 页面控制器

   
   package net.jackieathome.controller;
   
   import java.util.List;
   
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.web.bind.annotation.PathVariable;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RequestMethod;
   import org.springframework.web.bind.annotation.RestController;
   
   import net.jackieathome.bean.User;
   import net.jackieathome.dao.UserDao;
   import net.jackieathome.db.mapper.UserMapper;
   
   @RestController
   public class UserController {
   
       @Autowired
       private UserDao userDao;
   
       @RequestMapping(method = RequestMethod.GET, value = "/user/id/{id}")
       public User findUserById(@PathVariable("id") String id) {
           return userDao.findUserById(id);
       }
   
       @RequestMapping(method = RequestMethod.GET, value = "/user/create")
       public User createUser() {
           long time = System.currentTimeMillis() / 1000;
   
           String id = "id" + time;
           User user = new User();
           user.setId(id);
           userDao.createUser(user);
   
           return userDao.findUserById(id);
       }
   }

2. Mapper定义

   
   package net.jackieathome.db.mapper;
   
   import java.util.List;
   
   import org.apache.ibatis.annotations.Mapper;
   import org.apache.ibatis.annotations.Param;
   import org.springframework.cache.annotation.CacheConfig;
   import org.springframework.cache.annotation.CachePut;
   import org.springframework.cache.annotation.Cacheable;
   
   import net.jackieathome.bean.User;
   
   @Mapper
   public interface UserMapper {
   
       void createUser(User user);
   
       User findUserById(@Param("id") String id);
   }

3. 数据访问对象

   
   package net.jackieathome.dao;
   
   import java.util.ArrayList;
   import java.util.List;
   
   import org.apache.ibatis.annotations.Param;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.cache.annotation.CacheConfig;
   import org.springframework.cache.annotation.CachePut;
   import org.springframework.cache.annotation.Cacheable;
   import org.springframework.stereotype.Component;
   import org.springframework.transaction.annotation.Transactional;
   
   import net.jackieathome.bean.User;
   import net.jackieathome.db.mapper.UserMapper;
   
   @Component
   @CacheConfig(cacheNames = "users")
   @Transactional
   public class UserDao {
       private static final Logger LOG = LoggerFactory.getLogger(UserDao.class);
       @Autowired
       private UserMapper userMapper;
   
       @CachePut(key = "#p0.id")
       public void createUser(User user) {
           userMapper.createUser(user);
           LOG.debug("create user=" + user);
       }
   
       @Cacheable(key = "#p0")
       public User findUserById(@Param("id") String id) {
           LOG.debug("find user=" + id);
           return userMapper.findUserById(id);
       }
   }

方案二

直接在Mapper定义上增加缓存注解，控制缓存策略。从测试效果看，缓存有效，相比于方案一，测试代码更加简洁一些。

1. 页面控制器

   
   package net.jackieathome.controller;
   
   import java.util.List;
   
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.web.bind.annotation.PathVariable;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RequestMethod;
   import org.springframework.web.bind.annotation.RestController;
   
   import net.jackieathome.bean.User;
   import net.jackieathome.dao.UserDao;
   import net.jackieathome.db.mapper.UserMapper;
   
   @RestController
   public class UserController {
   
       @Autowired
       private UserMapper userMapper;
   
       @RequestMapping(method = RequestMethod.GET, value = "/user/id/{id}")
       public User findUserById(@PathVariable("id") String id) {
           return userMapper.findUserById(id);
       }
   
       @RequestMapping(method = RequestMethod.GET, value = "/user/create")
       public User createUser() {
           long time = System.currentTimeMillis() / 1000;
   
           String id = "id" + time;
           User user = new User();
           user.setId(id);
           userMapper.createUser(user);
   
           return userMapper.findUserById(id);
       }
   }

2. Mapper定义

   package net.jackieathome.db.mapper;
   
   import java.util.List;
   
   import org.apache.ibatis.annotations.Mapper;
   import org.apache.ibatis.annotations.Param;
   import org.springframework.cache.annotation.CacheConfig;
   import org.springframework.cache.annotation.CachePut;
   import org.springframework.cache.annotation.Cacheable;
   
   import net.jackieathome.bean.User;
   
   @CacheConfig(cacheNames = "users")
   @Mapper
   public interface UserMapper {
   
       @CachePut(key = "#p0.id")
       void createUser(User user);
   
       @Cacheable(key = "#p0")
       User findUserById(@Param("id") String id);
   }

总结

上述两个测试方案并没有优劣之分，仅是为了验证缓存的使用方法，体现了不同的控制粒度，在实际的项目开发过程中，需要依据实际情况做不同的决断。

缓存相关的注解：

1. CacheConfig
2. Cacheable
3. CachePut
4. CacheEvict

参考资料

使用redis缓存

• Caching
• spring-boot/spring-boot-samples/spring-boot-sample-cache
• Caching Data in Spring Using Redis
• Spring Boot使用redis做数据缓存
• Spring-boot用Redis 作为缓存服务
• Spring Boot中的缓存支持（二）使用Redis做集中式缓存
• Spring Boot使用redis做数据缓存
• Spring Boot下配置Redis缓存

MyBatis的缓存特性

• MyBatis Ehcache Adapter - Reference Documentation
• Mapper XML 文件
• mybatis缓存的使用及理解
• mybatis缓存
• MyBatis 缓存机制深度解剖 / 自定义二级缓存
• MyBatis的缓存配置(Cache)
• Mybatis二级缓存原理
• 深入浅出Mybatis-改造Cache
• mybatis的缓存机制（一级缓存二级缓存和刷新缓存）和mybatis整合ehcache
• 《深入理解mybatis原理》 MyBatis缓存机制的设计与实现
• 《深入理解mybatis原理》 MyBatis的二级缓存的设计原理
• mybatis入门基础(八)—–查询缓存

其它

1. 运行redis docker镜像的命令

   sudo docker run --rm -d -p 6379:6379 redis

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