redis(四)redis與Mybatis的無縫整合讓MyBatis透明的管理緩存

redis的安裝 http://liuyieyer.iteye.com/blog/2078093

redis的主從高可用  http://liuyieyer.iteye.com/blog/2078095

Mybatis 的使用很少說。

Mybatis爲了方便咱們擴展緩存定義了一個Cache接口，看看ehcache-mybatis的源碼就明白了。咱們要使用本身的cache一樣的實現Cache接口便可。直接上代碼

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("初始化鏈接池錯誤");
  }
  
  
  
}


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的源碼 它真正使用cache的方式是經過集成org.apache.ibatis.cache.decorators.LoggingCache 這個類實現的，照貓畫虎，直接咱們也繼承

public class LoggingRedisCache extends LoggingCache {

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

在mapper.xml中添加以下cache標籤

<!-- 啓用緩存 -->
  <cache type="cn.seafood.cache.LoggingRedisCache" />

 在mybatis的核心文件中開啓緩存

<settings>
    <!-- 這個配置使全局的映射器啓用或禁用緩存 -->
    <setting name="cacheEnabled" value="true" />
   <!-- 對於未知的SQL查詢，容許返回不一樣的結果集以達到通用的效果 -->    
  <setting name="multipleResultSetsEnabled" value="true"/>
    <!-- 配置默認的執行器。SIMPLE 執行器沒有什麼特別之處。REUSE 執行器重用預處理語句。BATCH 執行器重用語句和批量更新 -->
    <setting name="defaultExecutorType" value="REUSE" />
    <!-- 全局啓用或禁用延遲加載。當禁用時，全部關聯對象都會即時加載。 -->
    <setting name="lazyLoadingEnabled" value="false" />
    <setting name="aggressiveLazyLoading" value="true" />
    <!-- <setting name="enhancementEnabled" value="true"/> -->
    <!-- 設置超時時間，它決定驅動等待一個數據庫響應的時間。 -->
    <setting name="defaultStatementTimeout" value="25000" />
  </settings>

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

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

注意着兩個屬性，須要把屬性延遲加載和關聯對象加載給關閉了，否則放進redis中的cglib代理對象，在對數據發生更改的時候，會出錯。