java運行時getruntime exec超時返回出口總是NULL和總是TimeoutException？

Question

參考

使用Java的Runtime.exec（）時如何添加超時值？

但是我總是獲取worker.exit值NULL，所以它總是拋出超時異常。 下面是我的代碼

public class MyClass {


    private static class Worker extends Thread {
        private final Process process;
        private Integer exit;

        private Worker(Process process) {
            this.process = process;
        }

        public void run() {
            try {
                exit = process.waitFor();
            } catch (InterruptedException ignore) {
                return;
            }
        }
    }


    public String run(String command, long replyTimeout) throws Exception {

        StringBuffer output = new StringBuffer();
        Process p;
        p = Runtime.getRuntime().exec(command);

    BufferedReader errReader = new BufferedReader(new InputStreamReader(
            p.getErrorStream()));

    BufferedReader inputReader = new BufferedReader(new InputStreamReader(
            p.getInputStream()));

        Worker worker = new Worker(p);
        worker.start();

        try {
            worker.join(replyTimeout);              


            if (worker.exit != null) {
                if (worker.exit > 0) {

                    String line = "";
                    while ((line = errReader.readLine()) != null) {
                        output.append(line + "\n");
                    }
                    System.out.println(output.toString());
                    System.out.println(worker.exit);
                    throw new Exception(output.toString());
                } else {

                    String line = "";
                    while ((line = inputReader.readLine()) != null) {
                        output.append(line + "\n");
                    }
                    System.out.println(output.toString());
                    System.out.println(worker.exit);
                    return output.toString();
                }
            } else {
                throw new TimeoutException();
            }

        } catch (InterruptedException ex) {
            worker.interrupt();
            Thread.currentThread().interrupt();
            throw ex;
        } finally {
            p.destroy();
        }

    }



}

Answer 1

你做錯了所有。 您必須先消耗stdout和stderr上進程的所有輸出， 然后才可以調用waitFor（）。 否則，進程可能會阻止嘗試寫入自己的輸出。

另一方面，NullPointerExceptions只是由於瑣碎的編碼錯誤，希望您能夠自行解決。 至少我期望如此。