Mybatis 整合 redis

Mybatis为了方便我们扩展缓存定义了一个Cache接口，看看ehcache-mybatis的源码就明白了。我们要使用自己的cache同样的实现Cache接口即可。直接上代码

public class RedisCache implements Cache {
  private static Log logger = LogFactory.getLog(RedisCache.class);
  private Jedis redisClient = createClient();
  /** The ReadWriteLock. */
  private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

  private String id;
  public RedisCache(final String id) {
    if (id == null) {
      throw new IllegalArgumentException("Cache instances require an ID");
    }
    logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>MybatisRedisCache:id=" + id);
    this.id = id;
  }

  @Override
  public String getId() {
    return this.id;
  }

  @Override
  public int getSize() {
    return Integer.valueOf(redisClient.dbSize().toString());
  }

  @Override
  public void putObject(Object key, Object value) {
    logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>putObject:" + key + "=" + value);
    redisClient.set(SerializeUtil.serialize(key.toString()), SerializeUtil.serialize(value));
  }

  @Override
  public Object getObject(Object key) {
    Object value = SerializeUtil.unserialize(redisClient.get(SerializeUtil.serialize(key.toString())));
    logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>getObject:" + key + "=" + value);
    return value;
  }

  @Override
  public Object removeObject(Object key) {
    return redisClient.expire(SerializeUtil.serialize(key.toString()), 0);
  }

  @Override
  public void clear() {
    redisClient.flushDB();
  }

  @Override
  public ReadWriteLock getReadWriteLock() {
    return readWriteLock;
  }

  protected  static Jedis createClient() {
    try {
      JedisPool pool = new JedisPool(new JedisPoolConfig(), "172.60.0.172");
           return pool.getResource();
    } catch (Exception e) {
      e.printStackTrace();
    }
    throw new RuntimeException("初始化连接池错误");
  }

}


class SerializeUtil {
  public static byte[] serialize(Object object) {
    ObjectOutputStream oos = null;
    ByteArrayOutputStream baos = null;
    try {
      // 序列化
      baos = new ByteArrayOutputStream();
      oos = new ObjectOutputStream(baos);
      oos.writeObject(object);
      byte[] bytes = baos.toByteArray();
      return bytes;
    } catch (Exception e) {
      e.printStackTrace();
    }
    return null;
  }

  public static Object unserialize(byte[] bytes) {
    if(bytes == null)return null;
    ByteArrayInputStream bais = null;
    try {
      // 反序列化
      bais = new ByteArrayInputStream(bytes);
      ObjectInputStream ois = new ObjectInputStream(bais);
      return ois.readObject();
    } catch (Exception e) {
      e.printStackTrace();
    }
    return null;
  }
}

在看 ehcache-mybatis 的源码 它真正使用 cache 的方式是通过集成 org.apache.ibatis.cache.decorators.LoggingCache 这个类实现的，照猫画虎，直接我们也继承

public class LoggingRedisCache extends LoggingCache {

        public LoggingRedisCache(String id) {
                super(new RedisCache(id));
        }
}

在mapper.xml中添加如下cache标签

<!-- 启用缓存 -->
<cache type="cn.seafood.cache.LoggingRedisCache" />

在mybatis的核心文件中开启缓存

<settings>
    <!-- 这个配置使全局的映射器启用或禁用缓存 -->
    <setting name="cacheEnabled" value="true" />
   <!-- 对于未知的SQL查询，允许返回不同的结果集以达到通用的效果 -->    
  <setting name="multipleResultSetsEnabled" value="true"/>
    <!-- 配置默认的执行器。SIMPLE 执行器没有什么特别之处。REUSE 执行器重用预处理语句。BATCH 执行器重用语句和批量更新 -->
    <setting name="defaultExecutorType" value="REUSE" />
    <!-- 全局启用或禁用延迟加载。当禁用时，所有关联对象都会即时加载。 -->
    <setting name="lazyLoadingEnabled" value="false" />
    <setting name="aggressiveLazyLoading" value="true" />
    <!-- <setting name="enhancementEnabled" value="true"/> -->
    <!-- 设置超时时间，它决定驱动等待一个数据库响应的时间。 -->
    <setting name="defaultStatementTimeout" value="25000" />
</settings>

<setting name="lazyLoadingEnabled" value="false" />

<setting name="aggressiveLazyLoading" value="true" />

注意着两个属性，需要把属性延迟加载和关联对象加载给关闭了，不然放进redis中的cglib代理对象，在对数据发生更改的时候，会出错。