从Java运行外部程序，读取输出，允许中断

问题描述

我想从Java启动一个进程，读取它的输出，并获取它的返回代码。但是当它正在执行时，我希望能够取消它。我首先启动这个过程：

I want to launch a process from Java, read its output, and get its return code. But while it's executing, I want to be able to cancel it. I start out by launching the process:

ProcessBuilder pb = new ProcessBuilder(args);
pb.redirectErrorStream(true);
Process proc = pb.start();

如果我调用proc.waitFor（），在进程退出之前我无法执行任何操作。所以我假设我需要这样的东西：

If I call proc.waitFor(), I can't do anything until the process exits. So I'm assuming I need to something like this:

while (true) {
  see if process has exited
  capture some output from the process
  decide if I want to cancel it, and if so, cancel it
  sleep for a while
}

这是对的吗？有人能给我一个如何用Java做这个的例子吗？

Is this right? Can someone give me an example of how to do this in Java?

推荐答案

这是我想你想做的一个例子：

Here's an example of what I think you want to do:

ProcessBuilder pb = new ProcessBuilder(args);
pb.redirectErrorStream(true);
Process proc = pb.start();

InputStream is = proc.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);

String line;
int exit = -1;

while ((line = br.readLine()) != null) {
    // Outputs your process execution
    System.out.println(line);
    try {
        exit = proc.exitValue();
        if (exit == 0)  {
            // Process finished
        }
    } catch (IllegalThreadStateException t) {
        // The process has not yet finished.
        // Should we stop it?
        if (processMustStop())
            // processMustStop can return true
            // after time out, for example.
            proc.destroy();
    }
}

你可以改进它:-)我不知道有一个真实的环境来测试它，但你可以找到更多的信息。

You can improve it :-) I don't have a real environment to test it now, but you can find some more information here.

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