c# - 将 SqlDataReader 用作资源的习惯用法

Question

从 this 开始问题，我发现自己一遍又一遍地编写以下代码:

SqlCommand command = new SqlCommand();
// Code to initialize command with what we want to do
using (SqlConnection connection = openConnection())
{
    command.Connection = connection;
    using (SqlDataReader dataReader = thisCommand.ExecuteReader())
    {
        while (dataReader.Read())
        {
            // Do stuff with results
        }
    }
}

必须嵌套两个 using 语句是相当乏味的。有没有办法告诉 SqlDataReader 它拥有命令，并告诉命令它拥有连接？

如果有办法做到这一点，那么我可以编写一个可以像这样调用的辅助方法:

// buildAndExecuteCommand opens the connection, initializes the command
// with the connection and returns the SqlDataReader object. Dispose of the
// SqlDataReader to dispose of all resources that were acquired
using(SqlDataReader reader = buildAndExecuteCommand(...))
{
    // Do stuff with reader
}

还是我必须硬着头皮在 SqlDataReader 上编写自己的包装器？

Answer 1

一件事是编写一个为您处理的方法，将每个结果回调到一个委托(delegate)中。例如:

using (SqlConnection connection = openConnection())
{
    command.Connection = connection;
    ExecuteReaderWithCommand(command, reader =>
    {
        // Do stuff with the result here.
    });
}

然后 ExecuteReaderWithCommand 会是这样的:

public static void ExecuteReaderWithCommand(SqlCommand command,
    Action<SqlDataReader> action)
{
    using (SqlDataReader dataReader = thisCommand.ExecuteReader())
    {
        while (reader.Read())
        {
            action(reader);
        }
    }
}

如果您愿意，可以将其作为 SqlCommand 的扩展方法。哎呀，如果你愿意的话，你也可以去城里让它为你打开连接……你越能抽象出“打开/使用/关闭”的想法，就越好。