小编msg*_*msg的帖子

我正在尝试使用Java从外部启动一个进程,并且无法从其InputStream中读取任何内容.

如果我用"ls","ps"或"kill"等命令启动进程,一切正常.我可以在InputStream或Process的ErrorStream上启动该过程并获取信息.

如果我尝试使用像"ftp"或"telnet"这样的命令,则在尝试读取时,InputStream和ErrorStream都会阻塞我的程序.任何时候都不会通过这些流传递任何信息.

谁能解释一下这种行为？这些命令是不可能的,还是我的实现有问题？

     String processName = _configuration.getProgramCommand().getCommand();
   ProcessBuilder procBuilder = new ProcessBuilder(processName);   

   System.out.println("Starting process "+processName);   
   _proc = Runtime.getRuntime().exec(processName);// procBuilder.start();            

   if(!procBuilder.redirectErrorStream()) {    
    _errorWorker = new ProcessErrorWorker(_proc);
    _errorWorker.start();   
   }

   String proc_start_answer = _configuration.getNextCommand().getCommand();
   System.out.println("Waiting for process answer '"+proc_start_answer+"'");
   BufferedReader input = new BufferedReader(new InputStreamReader(_proc.getInputStream()));      

   String answer = "";  

   try {         
    System.out.println("inputstream ready: "+input.ready());
    answer+=input.readLine(); 
    System.out.println("process answer:  "+answer);
    input.close();        

   } catch(Exception e) {
    System.out.print(e.getMessage());     
   }