Control.OnDoubleClick(EventArgs) 方法

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

Source:

Control.cs

引发 DoubleClick 事件。

C#

protected virtual void OnDoubleClick(EventArgs e);

参数

e

EventArgs

包含事件数据的 EventArgs。

示例

下面的代码示例使用 DoubleClick 的 ListBox 事件将 中列出的文本文件加载到 控件TextBox中ListBox。

C#

// This example uses the DoubleClick event of a ListBox to load text files
// listed in the ListBox into a TextBox control. This example
// assumes that the ListBox, named listBox1, contains a list of valid file
// names with path and that this event handler method
// is connected to the DoublClick event of a ListBox control named listBox1.
// This example requires code access permission to access files.
private void listBox1_DoubleClick(object sender, System.EventArgs e)
{
    // Get the name of the file to open from the ListBox.
    String file = listBox1.SelectedItem.ToString();

    try
    {
        // Determine if the file exists before loading.
        if (System.IO.File.Exists(file))
        {
            // Open the file and use a TextReader to read the contents into the TextBox.
            System.IO.FileInfo myFile = new System.IO.FileInfo(listBox1.SelectedItem.ToString());
            System.IO.TextReader myData = myFile.OpenText();;

            textBox1.Text = myData.ReadToEnd();
            myData.Close();
        }
    }
        // Exception is thrown by the OpenText method of the FileInfo class.
    catch(System.IO.FileNotFoundException)
    {
        MessageBox.Show("The file you specified does not exist.");
    }
        // Exception is thrown by the ReadToEnd method of the TextReader class.
    catch(System.IO.IOException)
    {
        MessageBox.Show("There was a problem loading the file into the TextBox. Ensure that the file is a valid text file.");
    }
}

注解

引发事件时，将通过委托调用事件处理程序。 有关详细信息，请参阅 处理和引发事件。

OnDoubleClick 方法还允许派生类对事件进行处理而不必附加委托。 这是在派生类中处理事件的首选技术。

继承者说明

在派生类中重写 OnDoubleClick(EventArgs) 时，一定要调用基类的 OnDoubleClick(EventArgs) 方法，以便已注册的委托对事件进行接收。

适用于

另请参阅

• DoubleClick