如何从Java应用程序中打开和关闭监视器？

Question

How do you turn on and off a monitor from within a Java application?

In case you're wondering why, this is a kiosk style application where it would be great to turn off the monitors at night. Yes you can do it within the screensaver settings of the machine, but it would be great to do it programatically and avoid having to configure it on each machine.

Answer 1

Assuming you deploy your Java Applications on Windows, you can use this WIN32API functions:

// turn off monitor
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) 2); 

// turn on monitor
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) -1);    

Then you write a little C-JNI wrapper to functions that call the mentioned SendMessage and use the little wrapper to turn off the monitor from Java.

Answer 2

I have seen this exe named nircmd on the net. It is a freeware and can be used on by anyone.It has a built in function for doing this.

nircmd.exe monitor off 

A detailed help is also found in the website. Just use it in your program and call it using

Runtime.getRuntime().exec(this.getClass().getResource("nircmd.exe").getPath());

or put it to the windows directory and run it from there.

Answer 3

尽管可以使用Java查询监视器配置，但是如果不使用JNI，就无法以编程方式打开和关闭监视器。

Answer 4

您可以打开一个全屏的旋转窗口，使其全黑，因此，就可观察到的行为而言，显示器已关闭。