Mac 如果一定要写个锁屏程序的话就这样

package test;



import java.io.BufferedReader;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;



public class RuntimeCMD  {

	

	private static Process p;

	

	public static void main(String[] args) throws IOException, InterruptedException {

		InputStream in=getInputStreambyExecScript("scripts/test.sh");

		BufferedReader fr=new BufferedReader(new InputStreamReader(in));

		String line;

		while((line=fr.readLine())!=null){

			System.out.println(line);

		}

		p.waitFor();

		fr.close();

		p.destroy();

	}

	

	private static InputStream getInputStream(String exec) throws IOException{

		p=Runtime.getRuntime().exec(exec);

		return p.getInputStream();

	}

	

	private static InputStream getInputStreambyExecScript(String exec) throws IOException{

		p=Runtime.getRuntime().exec(new String[]{"/bin/sh","-c",exec},null,null);

		return p.getInputStream();

	}

}

 script 

#!/bin/bash

'/System/Library/CoreServices/Menu Extras/User.menu/Contents/Resources/CGSession' -suspend