在涉及线程时我很新,但在使用以下代码时我得到InvalidOperationException
。我知道它正在尝试访问importFileGridView
,但这是由创建异常的UI线程创建的。我的问题是,我该如何解决这个问题? GetAllImports可以有一个返回类型吗?如何从我的UI线程访问temp
?
ThreadPool.QueueUserWorkItem(new WaitCallback(GetAllImports), null);
private void GetAllImports(object x)
{
DataSet temp = EngineBllUtility.GetAllImportFiles(connectionString);
if (temp != null)
importFileGridView.DataSource = temp.Tables[0];
else
MessageBox.Show("There were no results. Please try a different search", "Unsuccessful", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
答案 0 :(得分:2)
您无法在后台线程上更改用户界面组件。在这种情况下,必须在UI线程上设置DataSource。
您可以通过Control.Invoke
或Control.BeginInvoke
处理此问题,如下所示:
private void GetAllImports(object x)
{
DataSet temp = EngineBllUtility.GetAllImportFiles(connectionString);
if (temp != null)
{
// Use Control.Invoke to push this onto the UI thread
importFileGridView.Invoke((Action)
() =>
{
importFileGridView.DataSource = temp.Tables[0];
});
}
else
MessageBox.Show("There were no results. Please try a different search", "Unsuccessful", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
答案 1 :(得分:0)
芦苇说了什么,但我更喜欢这种语法:
您正在创建一个委托函数,该函数将作为参数通过调用它的Control.Invoke
传递给UI线程,这样UI线程就会对importFileGridView
进行更改。
importFileGridView.Invoke((MethodInvoker) delegate {
importFileGridView.DataSource = temp.Tables[0];
});
您也可以这样写:
//create a delegate with the function signature
public delegate void SetDateSourceForGridViewDelegate (GridView gridView, Object dataSource);
//write a function that will change the ui
public void SetDataSourceForGridView(GridView gridView, Object dataSource)
{
gridView.DataSource = dataSource;
}
//Create a variable that will hold the function
SetDateSourceForGridViewDelegate delegateToInvoke = SetDataSourceForGridView;
//tell the ui to invoke the method stored in the value with the given paramters.
importFileGridView.Invoke(delegateToInvoke, importFileGridView, temp.Tables[0]);
我建议使用MethodInvoker
而不是Action
,请参阅:here