Question

我有以下方法，它们都返回不同的类型。我有四种这样的方法。本着良好编程实践（DRY）的精神，应该在这里使用一些OOP技术，例如继承或接口，或者只是使用它。欢迎任何评论或代码示例。谢谢。

  static AttendeeResponse GetAttendees(HttpWebRequest request)
    {
        HttpWebResponse resp = (HttpWebResponse)request.GetResponse();

        try
        {
            XmlSerializer ser = new XmlSerializer(typeof(AttendeeResponse));
            return (AttendeeResponse)ser.Deserialize(resp.GetResponseStream());
         }
        catch(Exception e)
        {
            error =  e.InnerException.ToString();
            return null;
        }

    }

    static MemberResponse GetMembers(HttpWebRequest request)
    {
        HttpWebResponse resp = (HttpWebResponse)request.GetResponse();

        try
        {
            XmlSerializer ser = new XmlSerializer(typeof(MemberResponse));
            return (MemberResponse)ser.Deserialize(resp.GetResponseStream());
        }
        catch (Exception e)
        {
            error = e.InnerException.ToString();
            return null;
        }

    }

Answer 1

怎么样：

// TODO: Improve the name :)
static T FetchItem<T>(HttpWebRequest request)
{
    using (HttpWebResponse resp = (HttpWebResponse)request.GetResponse())
    {
        try
        {
            XmlSerializer ser = new XmlSerializer(typeof(T));
            return (T) ser.Deserialize(resp.GetResponseStream());
        }
        catch (Exception e)
        {
            error = e.InnerException.ToString();
            return default(T);
        }
    }
}

请注意，我已添加using个参数，以避免泄露连接。根据文档，您也不需要关闭流。

如果return null是不可为空的值类型，则return default(T)必须更改为T;另一种方法是使用T作为方法声明的一部分，将where T : class限制为引用类型。

像这样使用：

MemberResponse members = FetchItem<MemberResponse>(request);
...
AttendeeResponse attendee = FetchItem<AttendeeResponse>(request);

Answer 2

使用泛型？

static T GetResponse<T>(HttpWebRequest request)
{
    HttpWebResponse resp = (HttpWebResponse)request.GetResponse();

    try
    {
        XmlSerializer ser = new XmlSerializer(typeof(T));
        return (T)ser.Deserialize(resp.GetResponseStream());
     }
    catch(Exception e)
    {
        error =  e.InnerException.ToString();
        return null;
    }

}

Answer 3

您可以使用泛型：

static T GetMembers<T>(HttpWebRequest request)
{
    HttpWebResponse resp = (HttpWebResponse)request.GetResponse();

    try
    {
        XmlSerializer ser = new XmlSerializer(typeof(T));
        return (T)ser.Deserialize(resp.GetResponseStream());
    }
    catch (Exception e)
    {
        error = e.InnerException.ToString();
        return null;
    }

}

Answer 4

它看起来像是一个很好的候选者。也许..？

static E GetPiece< E >(HttpWebRequest request)    {
{
   ...  
}

Answer 5

MemberResponse membResp = (MemberResponse )StaticClassName.SerializeIt(request);

static Object SerializeIt(HttpWebRequest request)
    {
        HttpWebResponse resp = (HttpWebResponse)request.GetResponse();

        try
        {
            XmlSerializer ser = new XmlSerializer(typeof(MemberResponse));
            return (Object)ser.Deserialize(resp.GetResponseStream());
        }
        catch (Exception e)
        {
            error = e.InnerException.ToString();
            return null;
        }

    }

Answer 6

您可以通过代理消除重复的代码。例如：如果我必须完成两个针对数据库的任务：

 OleDbCommand oci = new OleDbCommand(queryString, connection);
 oci.Connection.Open();
 oci.CommandText = "delete * from firstTable";
 oci.ExecuteNonQuery();
 oci.Connection.Close();

 OleDbCommand ocn = new OleDbCommand(queryString, connection);
 ocn.Connection.Open();
 ocn.CommandText = "select count(*) from secondTable";
 int affected = convert.ToInt32(ocn.ExecuteScalar();
 ocn.Connection.Close();

你可以看到我们这里有重复的代码。所以我需要像这样重构我的代码：

OleDbCommand myAccessCommand = null;
int count = -1;
OleDbWork(secondConnectionString, "SELECT COUNT(*) FROM   secondTable",
out myAccessCommand,
() =>
{
     count = Convert.ToInt32(myAccessCommand.ExecuteScalar());

});

OleDbWork(firstConnectionString, "delete * from firstTable",
out myAccessCommand,
() =>
{
    myAccessCommand.ExecuteNonQuery();
}

我的OleDbWork方法如下所示：

internal bool OleDbWork(string connString, string command,
out OleDbCommand myAccessCommand, Action action)
    {
        OleDbConnection myAccessConn = null;
        myAccessCommand = null;
        try
        {
            myAccessConn = new OleDbConnection(connString);
        }
        catch (Exception)
        {
            MessageBox.Show("Cannot connect to database!");

            return false;
        }

        try
        {

            myAccessCommand = new OleDbCommand(command, myAccessConn);

            myAccessConn.Open();

            action();
            return true;

        }
        catch (Exception ex)
        {
            MessageBox.Show("Cannot retrieve data from database. \n{0}",
            ex.Message);

            return false;
        }
        finally
        {
            myAccessConn.Close();
        }
    }

我希望这会有所帮助

如何消除重复的代码

6 个答案: