Question

我使用下面的代码从java运行cmd命令（从here采用的代码）

  private static void execute(File file){
   try {
        String[] command =
        {
           "cmd",
        };
        Process p = Runtime.getRuntime().exec(command);
        new Thread(new SyncPipe(p.getErrorStream(), System.err)).start();
        new Thread(new SyncPipe(p.getInputStream(), System.out)).start();
        PrintWriter stdin = new PrintWriter(p.getOutputStream());
        stdin.println("cd " + file.getParent());
        stdin.println("gxm -execute " + file.getPath());
        // write any other commands you want here
        stdin.close();
        int returnCode = p.waitFor();
        System.out.println("Return code = " + returnCode);
    }catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

SyncPipe类：

class SyncPipe implements Runnable
{
public SyncPipe(InputStream istrm, OutputStream ostrm) {
      istrm_ = istrm;
      ostrm_ = ostrm;
  }
  public void run() {
      try
      {
          final byte[] buffer = new byte[1024];
          for (int length = 0; (length = istrm_.read(buffer)) != -1; )
          {
              ostrm_.write(buffer, 0, length);
          }
      }
      catch (Exception e)
      {
          e.printStackTrace();
      }
  }
  private final OutputStream ostrm_;
  private final InputStream istrm_;
}

此代码工作正常，执行结果是一个名为COMPLETED的文件，但是我已经实现了以下方法来检查该文件以指示执行已完成。

  private static boolean checkFinished(String path)
{
    boolean result = false;
    String directory = path + "\\expts";
    File dir = new File(directory);
    if(dir.isDirectory())
        while(!result)
        {
            for(File f: dir.listFiles())
                if(!f.isDirectory() && "__COMPLETED__".equals(f.getName()))
                {
                    result = true;
                     break;
                }
            if(!result)
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    System.out.println(result);
    return result;

}

但是当我在主方法中调用这些方法时：

           File f = new File("C:\\inputFile.txt");
    execute(f);

    System.out.println(checkFinished(f.getParent()));

我得到以下输出：

false // printed from the checking
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
.... // rest of cmd output

这里的问题是checkFinshed方法打印一次，稍后当文件已经存在时打印为true。代码什么错了？

Answer 1

37次观看甚至没有评论!!无论如何，我将checkFinished方法更改为以下方法并且有效。希望它能使其他人受益。

  private static boolean checkFinished(String path)
{
    boolean result = false;
    String directory = path + "\\expts";
    File dir = new File(directory);
    while(true) 
    {
        try 
        {
            Thread.sleep(3000);
        } catch (InterruptedException e) 
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        if(dir.isDirectory())
        {
            for(File f: dir.listFiles())
                if(!f.isDirectory() && "__COMPLETED__".equals(f.getName()))
                {
                    result = true;
                    logger.info(" SIMULATOR:  simulation finished ");
                     break;
                }
            if(result)
                break;
        }
    }
    return result;
}

从java执行cmd命令后如何定期检查文件？

1 个答案: