【MQTT】paho.mqtt.c 库的“介绍、下载、交叉编译” 详解，以及编写MQTT客户端例子源码

[DllImport("shell32.dll", CharSet = CharSet.Auto)]
private static extern int IsImmersiveProcess(IntPtr hProcess);

[DllImport("kernel32.dll")]
private static extern IntPtr GetCurrentProcess();

[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr GetModuleHandle(string lpModuleName);

[DllImport("user32.dll")]
private static extern int ShowWindow(IntPtr hWnd, int nCmdShow);

[DllImport("user32.dll")]
private static extern bool SetForegroundWindow(IntPtr hWnd);

private const int SW_SHOWNORMAL = 1;
private const int SW_MINIMIZE= 6;

//返回桌面
private void button2_Click(object sender, EventArgs e)
{
    //以下三句代码是回到桌面的功能，调用了Windows系统命令
    Type shellType = Type.GetTypeFromProgID("Shell.Application");
    object shellObject = System.Activator.CreateInstance(shellType);
    shellType.InvokeMember("ToggleDesktop", System.Reflection.BindingFlags.InvokeMethod, null, shellObject, null);

    //以上三行是通用的，以下三行是针对win7系统的返回桌面操作 
    //需要引入System.Runtime.InteropServices
    IntPtr hWnd = GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName);
    ShowWindow(hWnd, SW_MINIMIZE);
    SetForegroundWindow(hWnd);

    Thread.Sleep(1000);
    this.TopMost = true;
}