1.功能需求 开发一个基于键盘和主机扬声器（小喇叭）的简易电子琴工具，同时它也可以自动的演奏指定的简谱文件。 通过调用计算机系统的API接口，导入kernel32.dll，调用相关的方法，开发基于键盘和扬声器的一个简易电子琴工具。主要是为了了解计算机操作系统中的相关API的知识，学会对API基本应用。 2.实验原理 引入[DllImport("kernel32.dll")]和[DllImport("winmm.dll")]。通过设置音频和时间间隔来播放声音。 [DllImport("kernel32.dll")]：是Windows 9x/Me中非常重要的32位动态链接库文件，属于内核级文件。它控制着系统的内存管理、数据的输入输出操作和中断处理，当Windows启动时，kernel32.dll就驻留在内存中特定的写保护区域，使别的程序无法占用这个内存区域。 [DllImport("winmm.dll")]：是Windows多媒体相关应用程序接口，用于低档的音频和游戏手柄。 3、实现代码 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; using System.Runtime.InteropServices; namespace test1 { public partial class Form1 : Form { [DllImport("kernel32.dll")] public static extern bool Beep(int freq, int duration); [DllImport("winmm.dll")] public static extern bool PlaySound(string pszSound, int hmod, int fdwSound);//播放windows音乐，重载 //进入系统播放音乐 private void m_SystemPlayWav(string strPlayFile) { try { if (strPlayFile.Trim() == "") { return; } int SND_FILENAME = 0x00020000; int SND_ASYNC = 0x0001; string strPath = AppDomain.CurrentDomain.SetupInformation.ApplicationBase; strPath = strPath + strPlayFile; PlaySound(strPath, 0, SND_ASYNC | SND_FILENAME);//播放音乐 } catch (Exception ex) { MessageBox.Show("播放失败","提示"); } } private void m_SystemStopPlayWav() { try { PlaySound(null, 0, 0x40 | 0x04 | 0x02); } catch (Exception ex) { MessageBox.Show("停止失败", "提示"); } } public Form1() { InitializeComponent(); } private void button2_Click(object sender, EventArgs e) { m_SystemPlayWav(comboBox1.SelectedItem.ToString()); } private void button3_Click(object sender, EventArgs e) { m_SystemStopPlayWav(); } private void button4_Click(object sender, EventArgs e) { Beep(400, 300); } private void button5_Click(object sender, EventArgs e) { Beep(500, 300); } private void button6_Click(object sender, EventArgs e) { Beep(600, 300); } private void button7_Click(object sender, EventArgs e) { Beep(700, 300); } private void button8_Click(object sender, EventArgs e) { Beep(800, 300); } private void button9_Click(object sender, EventArgs e) { Beep(900, 300); } private void button10_Click(object sender, EventArgs e) { Beep(1000, 300); } private void Form1_KeyDown(object sender, KeyEventArgs e) { if (e.KeyCode == Keys.D1) { button4.BackColor = System.Drawing.Color.LightGreen; ; button4.PerformClick(); button4.BackColor = System.Drawing.Color.Black; } if (e.KeyCode == Keys.D2) { button5.BackColor = System.Drawing.Color.LightGreen; button5.PerformClick(); button5.BackColor = System.Drawing.Color.White; } if (e.KeyCode == Keys.D3) { button6.BackColor = System.Drawing.Color.LightGreen; button6.PerformClick(); button6.BackColor = System.Drawing.Color.Black; } if (e.KeyCode == Keys.D4) { button7.BackColor = System.Drawing.Color.LightGreen; button7.PerformClick(); button7.BackColor = System.Drawing.Color.White; } if (e.KeyCode == Keys.D5) { button8.BackColor = System.Drawing.Color.LightGreen; button8.PerformClick(); button8.BackColor = System.Drawing.Color.Black; } if (e.KeyCode == Keys.D6) { button9.BackColor = System.Drawing.Color.LightGreen; button9.PerformClick(); button9.BackColor = System.Drawing.Color.White; } if (e.KeyCode == Keys.D7) { button10.BackColor = System.Drawing.Color.LightGreen; button10.PerformClick(); button10.BackColor = System.Drawing.Color.Black; } if (e.KeyCode == Keys.Enter) { button2.PerformClick();//enter键播放 } if (e.KeyCode == Keys.Space) { button3.PerformClick();//space键停止 } } } } | 