Question

我只是在学习使用Parallel.Invoke()并试图回过头来回复多个DataSets()例如，让我们采用下面的示例语法 - 我怎么能使用方法{ {1}}我需要返回3 ExecuteSqlQuery()中的每一个？

DataSets()

此项目的目标框架是Net Framework 4

Answer 1

尝试此解决方案，看看它是否适用于您的实例。

Software Cafe

（请注意，这是一个直接复制/粘贴，以防网站随时关闭）

protected void Page_Load(object sender, EventArgs e)
{
  SqlConnection cnn1 = new SqlConnection("Your connection string");
  SqlConnection cnn2 = new SqlConnection("Your connection string");
  SqlCommand cmd1;
  SqlCommand cmd2;
  IAsyncResult result1;
  IAsyncResult result2;
  SqlDataReader reader1;
  SqlDataReader reader2;

  try
  {
    cnn1.Open();

    cmd1 = new SqlCommand("SP1", cnn1);
    cmd1.CommandType = System.Data.CommandType.StoredProcedure;
    result1 = cmd1.BeginExecuteReader(CommandBehavior.SingleRow);

    cnn2.Open();
    cmd2 = new SqlCommand("SP2", cnn2);
    cmd2.CommandType = System.Data.CommandType.StoredProcedure;
    result2 = cmd2.BeginExecuteReader(CommandBehavior.SingleRow);

    reader1 = cmd1.EndExecuteReader(result1);

    if (reader1.Read())
    {
        Literal1.Text = reader1[0].ToString();
    }

    reader1.Close();

    reader2 = cmd2.EndExecuteReader(result2);

    if (reader2.Read())
    {
        Literal2.Text = reader2[0].ToString();
    }

    reader2.Close();
  }
  catch (Exception ex)
  {  
    // raise an exception or do whatever logic you want
  }
  finally
  {
    if (cnn1.State != System.Data.ConnectionState.Closed)
        cnn1.Close();

    if (cnn2.State != System.Data.ConnectionState.Closed)
        cnn2.Close();
  }
}

我在这台机器上没有编译器，但类似的东西应该允许你为每个存储过程返回一个数据集，或者这至少应该是一个很好的起点。理想情况下，您希望为每个连接使用using()语句以确保其正确处置，但这又是一个起点

protected void Page_Load(object sender, EventArgs e)
{
SqlCommand _sqlCommand1;
SqlCommand _sqlCommand2;
SqlCommand _sqlCommand3;
DataSet ds1 = new DataSet();
DataSet ds2 = new DataSet();
DataSet ds2 = new DataSet();
SqlDataAdapter _sqlDataAdapter1 = new SqlDataAdapter();
SqlDataAdapter _sqlDataAdapter2 = new SqlDataAdapter();
SqlDataAdapter _sqlDataAdapter3 = new SqlDataAdapter();
SqlConnection _sqlDatabaseConnection1;
SqlConnection _sqlDatabaseConnection2;
SqlConnection _sqlDatabaseConnection3;

try
{
  _connectionString = System.Configuration.ConfigurationManager.AppSettings[connectionString].ToString();
  _sqlDatabaseConnection1 = new SqlConnection(_connectionString);
  _sqlCommand1 = new SqlCommand("SP1", _sqlDatabaseConnection1);
  _sqlDatabaseConnection1.Open();
  _sqlCommand1.CommandTimeout = 0;
  ds1 = new DataSet();
  _sqlDataAdapter1 = new SqlDataAdapter(_sqlCommand1);
  _sqlDataAdapter1.Fill(ds1, "Data");
  return ds1;
  _sqlDatabaseConnection1.Close();
  _sqlCommand1.Dispose();
  _sqlDataAdapter1.Dispose();
  _connectionString = System.Configuration.ConfigurationManager.AppSettings[connectionString].ToString();
  _sqlDatabaseConnection2 = new SqlConnection(_connectionString);
  _sqlCommand2 = new SqlCommand("SP2", _sqlDatabaseConnection1);
  _sqlDatabaseConnection2.Open();
  _sqlCommand2.CommandTimeout = 0;
  ds2 = new DataSet();
  _sqlDataAdapter2 = new SqlDataAdapter(_sqlCommand1);
  _sqlDataAdapter2.Fill(ds2, "Data");
  return ds2;
  _sqlDatabaseConnection2.Close();
  _sqlCommand2.Dispose();
  _sqlDataAdapter2.Dispose();   
  _connectionString = System.Configuration.ConfigurationManager.AppSettings[connectionString].ToString();
  _sqlDatabaseConnection3 = new SqlConnection(_connectionString);
  _sqlCommand3 = new SqlCommand("SP3", _sqlDatabaseConnection1);
  _sqlDatabaseConnection3.Open();
  _sqlCommand3.CommandTimeout = 0;
  ds2 = new DataSet();
  _sqlDataAdapter3 = new SqlDataAdapter(_sqlCommand1);
  _sqlDataAdapter3.Fill(ds3, "Data");
  return ds3;
  _sqlDatabaseConnection3.Close();
  _sqlCommand3.Dispose();
  _sqlDataAdapter3.Dispose();

}
catch (Exception ex) { }
}

Answer 2

为什么不使用async / await方法并将它们以异步模式注册到页面中？ http://www.asp.net/web-forms/overview/performance-and-caching/using-asynchronous-methods-in-aspnet-45

更新：我将使用 4.0 中的 ASP.NET WebForms 分享执行异步进程的示例。首先，我定义了一个扩展方法实用程序，用于生成 PageAsyncTask ：

的实例

public static class PageAsyncTaskGenerator
{
    public static PageAsyncTask ToPageAsyncTask(this Task task, Action<IAsyncResult> onTimeout = null)
    {
        Func<Task> func = () => task;
        return new PageAsyncTask(
            (sender, e, cb, extraData) => func.BeginInvoke(cb, extraData),
            ar => func.EndInvoke(ar).Wait(),
            ar =>
            {
                if (onTimeout != null)
                {
                    onTimeout(ar);
                }
            }, 
            null);
    }
}

然后，在aspx文件中，您需要将 Async 属性标记为 true ：

<%@ Page Language="C#" AutoEventWireup="true" Async="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication1.Default" %>

然后，在您的代码隐藏中，只需创建一个Task并将其注册为此示例：

protected void Page_Load(object sender, EventArgs e)
{
    RegisterAsyncTask(LoadDataAsync().ToPageAsyncTask());
}

private Task LoadDataAsync()
{
    var t1 = ExecuteQueryAsync(databaseConnection, "exec FirstGraders ");
    var t2 = ExecuteQueryAsync(databaseConnection, "exec SecondGraders ");
    var t3 = ExecuteQueryAsync(databaseConnection, "exec ThirdGraders ");
    return Task.Factory.ContinueWhenAll(new[] { t1, t2, t3 }, _ => {
        gv1.DataSource = t1.Result;
        gv1.DataBind();
        gv2.DataSource = t2.Result;
        gv2.DataBind();
        gv3.DataSource = t3.Result;
        gv3.DataBind();
    });
}

private Task<DataSet> ExecuteSqlQueryAsync(string connectionString, string sqlQuery)
{
    return Task.Factory.StartNew(
    () =>
    {
        try
    {
        connstring = System.Configuration.ConfigurationManager.AppSettings[connectionString].ToString();
        dbconn = new SqlConnection(connstring);
        cm = new SqlCommand(sqlQuery, dbconn);
        dbconn.Open();
        cm.CommandTimeout = 0;
        datasetttt = new DataSet();
        da = new SqlDataAdapter(cm);
        da.Fill(datasetttt, "Data");
        return datasetttt;
    }
    catch (Exception exception) { throw exception; }
    finally
    {
        dbconn.Close();
        cm.Dispose();
        da.Dispose();
    }
    });
}

使用1 DataReader进行多个数据库调用

2 个答案: