springboot+mybatis+redis实现分布式缓存

大家都知道springboot项目都是微服务部署，A服务和B服务分开部署，那么它们如何更新或者获取共有模块的缓存数据，或者给A服务做分布式集群负载，如何确保A服务的所有集群都能同步公共模块的缓存数据，这些都涉及到分布式系统缓存的实现。

前面其实我已经介绍了springboot+mybatis+ehcache实现缓存数据，但是ehcache的设计并不适合做分布式缓存，所以今天用redis来实现分布式缓存。

原理什么的，我就不多说了，直接上代码。

pom依赖

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.2.4</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.1</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.42</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

表创建sql语句

CREATE TABLE `t_user` (
  `id` varchar(50) NOT NULL,
  `username` varchar(255) DEFAULT NULL,
  `password` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

application.properties配置文件

server.port=8860

# redis
spring.redis.database=1
spring.redis.host=127.0.0.1
spring.redis.password=test123
spring.redis.pool.max-active=8
spring.redis.pool.max-idle=8
spring.redis.pool.max-wait=-1
spring.redis.pool.min-idle=0
spring.redis.port=6379
#spring.redis.sentinel.master= # Name of Redis server.
#spring.redis.sentinel.nodes= # Comma-separated list of host:port pairs.
spring.redis.timeout=5000

# cache
spring.cache.cache-names=cache1,cache2
spring.cache.redis.time-to-live=600000

# datasource
spring.datasource.name=ehcahcetest
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3312/ehcahcetest
spring.datasource.username=root
spring.datasource.password=123456

# mybatis
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml
mybatis.config-location=classpath:mybatis/mybatis-config.xml
#mybatis.type-aliases-package=

springboot启动类

package com.rediscache;

import java.lang.reflect.Method;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.core.RedisTemplate;
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;

@SpringBootApplication
@ComponentScan(basePackages="com.rediscache")//扫描组件
@ServletComponentScan(basePackages="rediscache")//扫描拦截器，过滤器
@EnableCaching
public class RedisCacheTestApplication {

    /**
     * 设置缓存对象的序列化方式,不设置会报错
     * 另外对于json序列化,对象要提供默认空构造器
     * @param redisTemplate
     * @return
     */
    @Bean
    public CacheManager cacheManager(RedisTemplate redisTemplate) {

        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);
        redisTemplate.setValueSerializer(jackson2JsonRedisSerializer);

        RedisCacheManager cacheManager = new RedisCacheManager(redisTemplate);
        cacheManager.setDefaultExpiration(300);
        return cacheManager;
    }

    /**
     * 自定义key的生成策略
     * @return
     */
    @Bean
    public KeyGenerator myKeyGenerator(){
        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();
            }
        };
    }

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

}

接口测试类

package com.rediscache.controller;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.rediscache.entity.User;
import com.rediscache.factory.UserFactory;
import com.rediscache.service.UserService;
import com.google.gson.Gson;

@RestController
@RequestMapping("/o")
public class OperationController {

    @Autowired
    private StringRedisTemplate redisTemplate;

    @Autowired
    private UserService userService;

    Gson gson = new Gson();

    @RequestMapping(value = "/insert", method = RequestMethod.GET)
    public String insert(){

        // 保存一个新用户
        String uid = userService.save(UserFactory.createUser());

        return uid;
    }

    @RequestMapping(value = "/query", method = RequestMethod.GET)
    public String query(String uid){

        // 查询该用户
        System.out.println(gson.toJson(userService.getUserById(uid), User.class));
        System.out.println();

        return "success";
    }

    @RequestMapping(value = "/update", method = RequestMethod.GET)
    public String update(String uid, String username){

        User user = new User();
        user.setUid(uid);
        user.setUsername(username);

        // 更新该用户
        userService.update(user);

        return "success";
    }

    @RequestMapping(value = "/del", method = RequestMethod.GET)
    public String del(String uid){

        // 删除该用户
        userService.del(uid);
        System.out.println();

        return "success";
    }

}

service缓存类

package com.rediscache.service;

import java.util.Date;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

import com.rediscache.dao.UserDao;
import com.rediscache.entity.User;

@Service
public class UserService {

    @Autowired
    private UserDao userDao;

    @CacheEvict(key="'user_'+#uid", value="userCache")
    public void del(String uid) {
        // TODO Auto-generated method stub
        userDao.del(uid);
    }

    @CachePut(key="'user_'+#user.uid", value="userCache")
    public void update(User user) {
        userDao.update(user);
    }

    @Cacheable(key="'user_'+#uid",value="userCache")
    public User getUserById(String uid){
        System.err.println("缓存里没有"+uid+",所以这边没有走缓存，从数据库拿数据");
        return userDao.findById(uid);

    }

    @CacheEvict(key="'user'",value="userCache")
    public String save(User user) {
        // TODO Auto-generated method stub
        return userDao.save(user);
    }

}

其它的dao类和mybatis的mapper就不贴了。

复制上面写好的项目，把新项目的端口改为8862，现在分别启动8860和8862两个项目，模拟服务的集群部署。

开始测试

1、浏览器里输入http://localhost:8860/o/insert

可以看到数据库里保存进一条数据

2、输入http://localhost:8860/o/query?uid=ff4c5723-3ffc-438d-9d8c-8a2a7025b33e 查询刚刚的这条数据

可以看到sql语句打印了，提示也表示这一次没有走缓存

看看redis

说明缓存数据已经进来了。

3、再次http://localhost:8860/o/query?uid=ff4c5723-3ffc-438d-9d8c-8a2a7025b33e 查询

可以看到这次没有从数据库查，而是从缓存里获取的数据

说明单服务里的缓存已经奏效了，下面看看集群服务有没有效果

4、http://localhost:8862/o/query?uid=ff4c5723-3ffc-438d-9d8c-8a2a7025b33e 在8862服务里查询

这个是8862的控制台打印的结果，说明分布式缓存奏效了。

项目结构截图

注意点

缓存设置了时效的，也就是redis的时效