java process 不会关闭的解决方法

  String s;
  Process process = Runtime.getRuntime().exec("cmd /c dir + 执行命令");
  BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream());
while((s=bufferedReader.readLine()) != null)
 System.out.println(s);

 process.waitfor();

process.destroy();