如何：在 Windows 窗体内异步加载声音
下面的代码示例异步加载来自某一 URL 的声音，然后在新线程上播放它。
示例
Imports System
Imports System.Media
Imports System.Windows.Forms
Public Class Form1
Inherits System.Windows.Forms.Form
Friend WithEvents playSoundButton As System.Windows.Forms.Button
Private WithEvents Player As New SoundPlayer
Sub New()
Me.InitializeComponent()
End Sub
Private Sub playSoundButton_Click( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles playSoundButton.Click
' Replace this file name with a valid file name.
Me.Player.SoundLocation = "http://www.tailspintoys.com/sounds/stop.wav"
Me.Player.LoadAsync()
End Sub
Private Sub Player_LoadCompleted( _
ByVal sender As Object, _
ByVal e As _
System.ComponentModel.AsyncCompletedEventArgs) _
Handles Player.LoadCompleted
If Me.Player.IsLoadCompleted Then
Me.Player.Play()
End If
End Sub
'Form overrides dispose to clean up the component list.
<System.Diagnostics.DebuggerNonUserCode()> _
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing AndAlso components IsNot Nothing Then
components.Dispose()
End If
MyBase.Dispose(disposing)
End Sub
'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer
'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> _
Private Sub InitializeComponent()
Me.playSoundButton = New System.Windows.Forms.Button
Me.SuspendLayout()
'
'playSoundButton
'
Me.playSoundButton.Location = New System.Drawing.Point(105, 107)
Me.playSoundButton.Name = "playSoundButton"
Me.playSoundButton.Size = New System.Drawing.Size(75, 23)
Me.playSoundButton.TabIndex = 0
Me.playSoundButton.Text = "Play Sound"
Me.playSoundButton.UseVisualStyleBackColor = True
'
'Form1
'
Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
Me.ClientSize = New System.Drawing.Size(292, 273)
Me.Controls.Add(Me.playSoundButton)
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
End Sub
<STAThread()> _
Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New Form1())
End Sub
End Class
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Media;
using System.Windows.Forms;
namespace SoundPlayerLoadAsyncExample
{
public class Form1 : Form
{
private SoundPlayer Player = new SoundPlayer();
public Form1()
{
InitializeComponent();
this.Player.LoadCompleted += new AsyncCompletedEventHandler(Player_LoadCompleted);
}
private void playSoundButton_Click(object sender, EventArgs e)
{
this.LoadAsyncSound();
}
public void LoadAsyncSound()
{
try
{
// Replace this file name with a valid file name.
this.Player.SoundLocation = "http://www.tailspintoys.com/sounds/stop.wav";
this.Player.LoadAsync();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Error loading sound");
}
}
// This is the event handler for the LoadCompleted event.
void Player_LoadCompleted(object sender, AsyncCompletedEventArgs e)
{
if (Player.IsLoadCompleted)
{
try
{
this.Player.Play();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Error playing sound");
}
}
}
private Button playSoundButton;
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.playSoundButton = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// playSoundButton
//
this.playSoundButton.Location = new System.Drawing.Point(106, 112);
this.playSoundButton.Name = "playSoundButton";
this.playSoundButton.Size = new System.Drawing.Size(75, 23);
this.playSoundButton.TabIndex = 0;
this.playSoundButton.Text = "Play Sound";
this.playSoundButton.Click += new System.EventHandler(this.playSoundButton_Click);
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.Add(this.playSoundButton);
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);
}
#endregion
}
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form1());
}
}
}
编译代码
此示例需要：
对 System 和 System.Windows.Forms 程序集的引用。
以有效文件名替换文件名 "http://www.tailspintoys.com/sounds/stop.wav"。
有关从 Visual Basic 或 Visual C# 的命令行生成此示例的信息，请参见从命令行生成 (Visual Basic) 或在命令行上使用 csc.exe 生成。 也可以通过将代码粘贴到新项目，在 Visual Studio 中生成此示例。 有关更多信息，请参见 如何：使用 Visual Studio 编译和运行完整的 Windows 窗体代码示例 和 如何：使用 Visual Studio 编译和运行完整的 Windows 窗体代码示例 和 如何：使用 Visual Studio 编译和运行完整的 Windows 窗体代码示例 和 如何：使用 Visual Studio 编译和运行完整的 Windows 窗体代码示例 和 如何：使用 Visual Studio 编译和运行完整的 Windows 窗体代码示例.
可靠编程
文件操作应该包含在适当的异常处理块中。
以下情况可能会导致异常：
路径名格式不正确。 例如，它包含无效字符或仅仅是空白（ArgumentException 类）。
路径是只读的（IOException 类）。
路径名为 Nothing（ArgumentNullException 类）。
路径名太长（PathTooLongException 类）。
路径无效（DirectoryNotFoundException 类）。
路径仅是一个冒号“:”（NotSupportedException 类）。
安全性
不要根据文件的名称来判断文件的内容。 例如，Form1.vb 文件可能不是 Visual Basic 源文件。 在应用程序中使用输入的数据之前，需验证所有的输入内容。