SqlSesion怎麽獲取一個Mapper？

一個Mapper接口沒有一個實現類怎麽能夠實例化？

public <T> T getMapper(Class<T> type) {
    // 通過 configuration 的getMapper方法獲取Mapper對象
    return configuration.<T>getMapper(type, this);
  }

  public <T> T getMapper(Class<T> type, SqlSession sqlSession) {
    // 通過MapperRegistry對象獲取 Mapper的對象
 

    return mapperRegistry.getMapper(type, sqlSession);
  }

  public <T> T getMapper(Class<T> type, SqlSession sqlSession) {
    // 通過註冊的 mapperProxy 獲取mapperProxyFactory 這裏的knownMappers 在解析 mapper 的時候添加進入的
    final MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory<T>) knownMappers.get(type);
    
 
if (mapperProxyFactory == null)
      throw new BindingException("Type " + type + " is not known to the MapperRegistry.");
    try {
      // 通過mapperProxyFactory 實例化一個對象
      return mapperProxyFactory.newInstance(sqlSession);
    } catch (Exception e) {
      throw new BindingException("Error getting mapper instance. Cause: " + e, e);
    }
  }

  
 
public T newInstance(SqlSession sqlSession) {
    //MapperProxy 繼承了 InvocationHandler
    final MapperProxy<T> mapperProxy = new MapperProxy<T>(sqlSession, mapperInterface, methodCache);
    return newInstance(mapperProxy);
  }

  protected T newInstance(MapperProxy<T> mapperProxy) {
    // 動態代理的對像
    return (T) Proxy.newProxyInstance(mapperInterface.getClassLoader(), new Class[] { mapperInterface }, mapperProxy);
  }

答案：動態代理

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