public?class?ItemsDAO?{
	/*獲得所有商品*/
	public?ArrayList<Items>?getAllItems(){
		Connection?conn=null;
		PreparedStatement?stmt=null;		
		String?sql="select?*?from?shop";
		ResultSet?rs=null;
		ArrayList<Items>?list=new?ArrayList<Items>();
		try
		{
			conn=DBHelper.getConnection();
			stmt=conn.prepareStatement(sql);
			rs=stmt.executeQuery();
			while(rs.next())
			{
				Items?item=new?Items();
				item.setId(rs.getInt("id"));
				item.setName(rs.getString("name"));
				item.setCity(rs.getString("city"));
				item.setNumber(rs.getInt("number"));
				item.setPicture(rs.getString("picture"));
				item.setPrice(rs.getInt("price"));
				list.add(item);
			}
			return?list;
		}catch(Exception?ex)
		{
			ex.printStackTrace();
			return?null;
		}finally
		{
			/*釋放結果集*/
			if(rs!=null)
			{
				try
				{
					rs.close();
				}
				catch(Exception?ex)
				{
					ex.printStackTrace();
				}
			}
			/*釋放statement*/
			if(stmt!=null)
			{
				try
				{
					stmt.close();
				}
				catch(Exception?ex)
				{
					ex.printStackTrace();
				}
			}
			/*是需要釋放數據庫連接呢？老師講解時，沒有提到這一點*/
			if(conn!=null)
			{
				try
				{
					conn.close();
				}
				catch(Exception?ex)
				{
					ex.printStackTrace();
				}
			}
		}
	}

后面的兩個方法getItemsById和getItemsByList里面還要重新建立連接的。每次執行方法之后，要不要關閉呢？