java - 运行时立即获取系统输出(更新 ProgressBar)Java

Question

我正在通过 runtime.exec 运行命令，这需要一些时间。我想在那个时候更新我的 ProgressBar。
我已经得到了我想要的系统输出，问题是:我在进程完成时立即得到它。而不是一步一步地更新我的 ProgressBar ...

代码如下

public Runtime rt = Runtime.getRuntime();
public Process pp;

  public doit() {
      try {
          pp = rt.exec(a_long_timed_process);
          InputStream is = pp.getErrorStream();
          InputStreamReader isr = new InputStreamReader(is);
          BufferedReader br = new BufferedReader(isr);
          String line = null;
          while ((line = br.readLine()) != null) {
              if (line.contains("In:")) {
                  int a = line.indexOf("In:");              //get a string
                  int b = line.lastIndexOf("%");            //between 
                  String lineout = line.substring(a + 3, b);//"0.00" and "99.99"
                  double nr = Double.parseDouble(lineout);  //make it a double
                  int round = (int) nr;                     //make it a usable int
                  System.out.println(round);
                  myProgressBar.setValue(round);            //UPDATE Progressbar
              }
          }
          pp.waitFor();
      } catch (IOException ex) {
          Logger.getLogger(Sox.class.getName()).log(Level.SEVERE, null, ex);
      } catch (InterruptedException ex) {
          Logger.getLogger(Sox.class.getName()).log(Level.SEVERE, null, ex);
      }
  }

感谢您的帮助
提前致谢

Answer 1

如果您希望能够并发处理其输出，则必须在不同的线程中运行该进程。一个好方法是使用 ProcessBuilder .

来自文档:

This class is used to create operating system processes.

[...]

Starting a new process which uses the default working directory and environment is easy:

Process p = new ProcessBuilder("myCommand", "myArg").start();

Here is an example that starts a process with a modified working directory and environment, and redirects standard output and error to be appended to a log file:

ProcessBuilder pb =
  new ProcessBuilder("myCommand", "myArg1", "myArg2");
Map<String, String> env = pb.environment();
env.put("VAR1", "myValue");
env.remove("OTHERVAR");
env.put("VAR2", env.get("VAR1") + "suffix");
pb.directory(new File("myDir"));
File log = new File("log");
pb.redirectErrorStream(true);
pb.redirectOutput(Redirect.appendTo(log));
Process p = pb.start();
assert pb.redirectInput() == Redirect.PIPE;
assert pb.redirectOutput().file() == log;
assert p.getInputStream().read() == -1;

另见 here另一个代码示例，您可以根据自己的需要进行调整。