为什么建议框架源码学习从Mybatis开始（下）

private Executor delegate;
private TransactionalCacheManager tcm = new TransactionalCacheManager();
public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)
      throws SQLException {
        Cache cache = ms.getCache();
        ....
        List<E> list = (List<E>) tcm.getObject(cache, key);
        if (list == null) {
          list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
          tcm.putObject(cache, key, list); // issue #578 and #116
        }
        return list;
      }
    }
    return delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
  }

public void commit(boolean required) throws SQLException {
    delegate.commit(required);
    tcm.commit();也就是事务提交时才会将数据放入到二级缓存中去
}

public Executor newExecutor(Transaction transaction, ExecutorType executorType) {
    ..
      executor = new SimpleExecutor(this, transaction);
    ....
    if (cacheEnabled) {
      executor = new CachingExecutor(executor);
    }
    插件的入口
    executor = (Executor) interceptorChain.pluginAll(executor);
    return executor;
  }
InterceptorChain
 public Object pluginAll(Object target) {
    for (Interceptor interceptor : interceptors) {
      target = interceptor.plugin(target);
    }
    return target;
  }

QueryInterceptor
public Object plugin(Object target) {
        return Plugin.wrap(target, this);
}
public class Plugin implements InvocationHandler {
public static Object wrap(Object target, Interceptor interceptor) {
    Map<Class<?>, Set<Method>> signatureMap = getSignatureMap(interceptor);
    Class<?> type = target.getClass();
    Class<?>[] interfaces = getAllInterfaces(type, signatureMap);
    if (interfaces.length > 0) {
      return Proxy.newProxyInstance(
          type.getClassLoader(),
          interfaces,
          new Plugin(target, interceptor, signatureMap));
    }
    return target;
  }
}