本片文章续《Spring Boot 入门（九）：集成Quartz定时任务》。本文主要基于redis实现了mybatis二级缓存。较redis缓存，mybaits自带缓存存在缺点（自行谷歌）。本文是基于docker安装redis主从模式。

（1）首先安装redis集群模式，建立redis目录，并编写主从模式docker-compose.yml文件

  1.  1 version: '3.1'
  2.  2 services:
  3.  3   master:  
  4.  4     image: redis
  5.  5     container_name: redis-master
  6.  6     ports:
  7.  7       - 6379:6379
  8.  8         
  9.  9   slave1:  
  10. 10     image: redis
  11. 11     container_name: redis-slave-1
  12. 12     ports:
  13. 13       - 6380:6379
  14. 14     command: redis-server --slaveof redis-master 6379
  15. 15           
  16. 16   slave2:  
  17. 17     image: redis
  18. 18     container_name: redis-slave-2
  19. 19     ports:
  20. 20       - 6381:6379
  21. 21     command: redis-server --slaveof redis-master 6379

（2）.启动 docker-compose up -d

（3）.建立sentinel文件，并编写docker-compose.yml文件

  1.  1 version: '3.1'
  2.  2 services:
  3.  3   sentinel1:  
  4.  4     image: redis
  5.  5     container_name: redis-sentinel-1
  6.  6     ports:
  7.  7       - 26379:26379
  8.  8     command: redis-sentinel /usr/local/etc/redis/sentinel.conf
  9.  9     volumes:
  10. 10       - ./sentinel1.conf:/usr/local/etc/redis/sentinel.conf
  11. 11         
  12. 12   sentinel2:  
  13. 13     image: redis
  14. 14     container_name: redis-sentinel-2
  15. 15     ports:
  16. 16       - 26380:26379
  17. 17     command: redis-sentinel /usr/local/etc/redis/sentinel.conf
  18. 18     volumes:
  19. 19       - ./sentinel2.conf:/usr/local/etc/redis/sentinel.conf
  20. 20         
  21. 21   sentinel3:  
  22. 22     image: redis
  23. 23     container_name: redis-sentinel-3
  24. 24     ports:
  25. 25       - 26381:26379
  26. 26     command: redis-sentinel /usr/local/etc/redis/sentinel.conf
  27. 27     volumes:
  28. 28       - ./sentinel3.conf:/usr/local/etc/redis/sentinel.conf
  29. 29

从模式需要sentinel的conf文件，我创建了3个容器，所以这里需要3份（sentinel1.conf sentinel2.conf sentinel3.conf），内容是一模一样

  1. 1 port 26379
  2. 2 dir /tmp
  3. 3 sentinel monitor mymaster 217.0.0.1 6379 2
  4. 4 sentinel down-after-milliseconds rmaster 30000
  5. 5 sentinel parallel-syncs mymaster 1
  6. 6 sentinel failover-timeout mymaster 180000
  7. 7 sentinel deny-scripts-reconfig yes

（4）.启动：docker-compose up -d

（5）.验证redis是否已经成功启动

进入容器：docker exec -it redis-sentinel-1 /bin/bash

连接redis：redis-cli -p 26379

如下图，表示启动成功

 

也可以通过桌面客户端查看是否启动成功，如图，我使用的RedisDesktopManager客户端

 

 

网上一大堆，根据自己需要选择合适的utils（有的utils中方法很全）

  1.   1 package com.learn.hello.system.utils;
  2.   2 
  3.   3 import lombok.extern.slf4j.Slf4j;
  4.   4 import org.apache.ibatis.cache.Cache;
  5.   5 import org.springframework.data.redis.core.RedisCallback;
  6.   6 import org.springframework.data.redis.core.RedisTemplate;
  7.   7 import org.springframework.data.redis.core.ValueOperations;
  8.   8 
  9.   9 import java.util.concurrent.TimeUnit;
  10.  10 import java.util.concurrent.locks.ReadWriteLock;
  11.  11 import java.util.concurrent.locks.ReentrantReadWriteLock;
  12.  12 
  13.  13 /**
  14.  14  * @ClassName RedisCache
  15.  15  * @Deccription 通过redis实现mybaits的二级缓存
  16.  16  * @Author DZ
  17.  17  * @Date 2020/1/12 22:41
  18.  18  **/
  19.  19 @Slf4j
  20.  20 public class RedisCache implements Cache {
  21.  21 
  22.  22     private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
  23.  23     private final String id; // cache instance id
  24.  24     private RedisTemplate redisTemplate;
  25.  25 
  26.  26     private static final long EXPIRE_TIME_IN_MINUTES = 30; // redis过期时间
  27.  27 
  28.  28     public RedisCache(String id) {
  29.  29         if (id == null) {
  30.  30             throw new IllegalArgumentException("Cache instances require an ID");
  31.  31         }
  32.  32         this.id = id;
  33.  33     }
  34.  34 
  35.  35     @Override
  36.  36     public String getId() {
  37.  37         return id;
  38.  38     }
  39.  39 
  40.  40     /**
  41.  41      * Put query result to redis
  42.  42      *
  43.  43      * @param key
  44.  44      * @param value
  45.  45      */
  46.  46     @Override
  47.  47     public void putObject(Object key, Object value) {
  48.  48         try {
  49.  49             RedisTemplate redisTemplate = getRedisTemplate();
  50.  50             ValueOperations opsForValue = redisTemplate.opsForValue();
  51.  51             opsForValue.set(key, value, EXPIRE_TIME_IN_MINUTES, TimeUnit.MINUTES);
  52.  52             log.debug("Put query result to redis");
  53.  53         } catch (Throwable t) {
  54.  54             log.error("Redis put failed", t);
  55.  55         }
  56.  56     }
  57.  57 
  58.  58     /**
  59.  59      * Get cached query result from redis
  60.  60      *
  61.  61      * @param key
  62.  62      * @return
  63.  63      */
  64.  64     @Override
  65.  65     public Object getObject(Object key) {
  66.  66         try {
  67.  67             RedisTemplate redisTemplate = getRedisTemplate();
  68.  68             ValueOperations opsForValue = redisTemplate.opsForValue();
  69.  69             log.debug("Get cached query result from redis");
  70.  70             return opsForValue.get(key);
  71.  71         } catch (Throwable t) {
  72.  72             log.error("Redis get failed, fail over to db", t);
  73.  73             return null;
  74.  74         }
  75.  75     }
  76.  76 
  77.  77     /**
  78.  78      * Remove cached query result from redis
  79.  79      *
  80.  80      * @param key
  81.  81      * @return
  82.  82      */
  83.  83     @Override
  84.  84     @SuppressWarnings("unchecked")
  85.  85     public Object removeObject(Object key) {
  86.  86         try {
  87.  87             RedisTemplate redisTemplate = getRedisTemplate();
  88.  88             redisTemplate.delete(key);
  89.  89             log.debug("Remove cached query result from redis");
  90.  90         } catch (Throwable t) {
  91.  91             log.error("Redis remove failed", t);
  92.  92         }
  93.  93         return null;
  94.  94     }
  95.  95 
  96.  96     /**
  97.  97      * Clears this cache instance
  98.  98      */
  99.  99     @Override
  100. 100     public void clear() {
  101. 101         RedisTemplate redisTemplate = getRedisTemplate();
  102. 102         redisTemplate.execute((RedisCallback) connection -> {
  103. 103             connection.flushDb();
  104. 104             return null;
  105. 105         });
  106. 106         log.debug("Clear all the cached query result from redis");
  107. 107     }
  108. 108 
  109. 109     /**
  110. 110      * This method is not used
  111. 111      *
  112. 112      * @return
  113. 113      */
  114. 114     @Override
  115. 115     public int getSize() {
  116. 116         return 0;
  117. 117     }
  118. 118 
  119. 119     @Override
  120. 120     public ReadWriteLock getReadWriteLock() {
  121. 121         return readWriteLock;
  122. 122     }
  123. 123 
  124. 124     private RedisTemplate getRedisTemplate() {
  125. 125         if (redisTemplate == null) {
  126. 126             redisTemplate = SpringContextHolder.getBean("redisTemplate");
  127. 127         }
  128. 128         return redisTemplate;
  129. 129     }
  130. 130 }
  1. @CacheNamespace(implementation = RedisCache.class)

例如：

  1. 1 @CacheNamespace(implementation = RedisCache.class)
  2. 2 public interface RoleMapper extends MyMapper<Role> {
  3. 3     List<Role> selectByCondition(ModelMap modelMap);
  4. 4 
  5. 5     Role selectById(int id);
  6. 6 
  7. 7     List<Role> selectAllRole();
  8. 8 }

这里也可以直接在MyMapper父接口中增加注解，这样，所有的接口就不需要单独增加这个注解（根据业务需要自行素选择）。

当进行CURD操作时，相关的检索sql语句就会缓存到redis，如图：

 

 当再次对相关数据进行CRUD时，就会走缓存

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本文链接：https://www.cnblogs.com/dz-boss/p/12190065.html