java - 如果是 java，则 ProcessBuilder 不显示输出流

Question

如果我执行“dir”之类的命令，我会得到一个正在运行并成功显示输出的代码，但如果我运行“java -version”或来自 java 的其他命令，则不会显示输出。请帮忙:

public static void execJob(){

    try{        

    ProcessBuilder pb = new ProcessBuilder("C:\\myPrograms\\jdk1.7.0_79\\bin\\java.exe", "-version");
    pb.directory(new File("src"));
    Process process = pb.start();
    IOThreadHandler outputHandler = new IOThreadHandler(process.getInputStream());
    outputHandler.start();
    process.waitFor();

    System.out.println(outputHandler.getOutput());
    }catch(Exception e) {
        System.out.println(e.toString());
    }

}

private static class IOThreadHandler extends Thread {
    private InputStream inputStream;
    private StringBuilder output = new StringBuilder();

    IOThreadHandler(InputStream inputStream) {
        this.inputStream = inputStream;
    }

    public void run() {
        Scanner br = null;
        try {
            br = new Scanner(new InputStreamReader(inputStream));
            String line = null;
            while (br.hasNextLine()) {
                line = br.nextLine();
                output.append(line + System.getProperty("line.separator"));
            }
        } finally {
            br.close();
        }
    }

Answer 1

java -version 写入 stderr，因此您需要 pb.redirectErrorStream(true); 来捕获输出。

 ProcessBuilder pb = new ProcessBuilder("C:\\myPrograms\\jdk1.7.0_79\\bin\\java.exe", "-version");
 pb.redirectErrorStream(true);
 ...