java.lang.ProcessBuilder.Redirect#PIPE源码实例Demo

/**
 * Returns a {@link ProcessBuilder.Redirect} appropriate for the parameters. If a file redirected
 * to exists, deletes the file before redirecting to it.
 */
private Redirect getRedirect(StreamAction action, File file) {
  switch (action) {
    case DISCARD:
      return Redirect.to(new File("/dev/null"));

    case REDIRECT:
      // We need to use Redirect.appendTo() here, because on older Linux kernels writes are
      // otherwise not atomic and might result in lost log messages:
      // https://lkml.org/lkml/2014/3/3/308
      if (file.exists()) {
        file.delete();
      }
      return Redirect.appendTo(file);

    case STREAM:
      return Redirect.PIPE;

    default:
      throw new IllegalStateException();
  }
}
 

/**
 * Returns a {@link java.lang.ProcessBuilder.Redirect} appropriate for the parameters. If a file
 * redirected to exists, deletes the file before redirecting to it.
 */
private Redirect getRedirect(StreamAction action, File file) {
  switch (action) {
    case DISCARD:
      return Redirect.to(new File("/dev/null"));

    case REDIRECT:
      // We need to use Redirect.appendTo() here, because on older Linux kernels writes are
      // otherwise not atomic and might result in lost log messages:
      // https://lkml.org/lkml/2014/3/3/308
      if (file.exists()) {
        file.delete();
      }
      return Redirect.appendTo(file);

    case STREAM:
      return Redirect.PIPE;

    default:
      throw new IllegalStateException();
  }
}
 

RedirectInfo() {
    this.hasRedirects = false;
    this.inputRedirect = Redirect.PIPE;
    this.outputRedirect = Redirect.PIPE;
    this.errorRedirect = Redirect.PIPE;
    this.mergeError = false;
}
 

public List<String> runCommand(
  final List<String> command,
  final Redirect redirectOutput,
  final Set<Integer> acceptableExitCodes
)
  throws InterruptedException, ProcessFailedException {
  final ProcessBuilder processBuilder = new ProcessBuilder(command);

  Optional<Integer> exitCode = Optional.empty();

  Optional<OutputReader> reader = Optional.empty();

  String processToString = getCurrentProcessToString();

  try {
    processBuilder.redirectError(Redirect.INHERIT);
    processBuilder.redirectOutput(redirectOutput);

    final Process process = startProcess(processBuilder);

    processToString = getCurrentProcessToString();

    if (redirectOutput == Redirect.PIPE) {
      reader = Optional.of(new OutputReader(process.getInputStream()));
      reader.get().start();
    }

    exitCode = Optional.of(process.waitFor());

    if (reader.isPresent()) {
      reader.get().join();

      if (reader.get().error.isPresent()) {
        throw reader.get().error.get();
      }
    }
  } catch (InterruptedException ie) {
    signalKillToProcessIfActive();

    throw ie;
  } catch (Throwable t) {
    getLog().error("Unexpected exception while running {}", processToString, t);

    signalKillToProcessIfActive();

    throw new RuntimeException(t);
  } finally {
    processFinished(exitCode);
  }

  if (exitCode.isPresent() && !acceptableExitCodes.contains(exitCode.get())) {
    throw new ProcessFailedException(
      String.format(
        "Got unacceptable exit code %s while running %s",
        exitCode,
        processToString
      )
    );
  }

  if (!reader.isPresent()) {
    return Collections.emptyList();
  }

  return reader.get().output;
}