Windows上无缓冲的子进程标准输出

Question

Is there an easy way to read output from subprocess unbuffered? I'm trying to call a C program from Java, but apparently it's stdout block-buffered when connected to pipe and line-buffered only when connected to console. I cannot modify C program.

Maybe there is a way to fool the program into thinking it is connected to console? Bonus points for a solution that works on linux as well.

Answer 1

这不是一个很好的解决方案，但运行时库可能不会缓冲串行端口，所以如果你非常绝望，你可以使用零调制解调器模拟器，如com0com或其衍生物。

Answer 2

您是否尝试过使用环境变量BUF_1_ = 0？

Answer 3

OK -

1) "Line buffered input" is a common idiom for console-mode programs, dating back to the original Unix and serial-mode VTxx terminals.

2) You can read "raw, unbuffered" I/O (a keystroke at a time, instead of a line at a time), but the details are OS specific. Whatever you need to do on a specific OS, you almost certainly can do from Java.

3) It sounds like you want to be able to intercept an "arrow up" key or "page down" key, as it happens, on a Windows keyboard. Perhaps for playing a game, or for interacting with a console-mode user interface.

4) There are several options. One you might wish to consider is the "robot" API, used for testing:

• http://www.java-tips.org/java-se-tips/java.awt/how-to-use-robot-class-in-java.html

If that's not sufficient, please give more details about exactly how you're trying to get your Java program to interact with the C program (and clarify if the platform is indeed Windows and a DOS prompt).

Answer 4

您可以将c输出重定向到文件，然后使用java中的另一个线程拖尾文件

org.apache.commons.io.input.Tailer

Answer 5

The best way to do it is using Threads to read the output

What I would do is: using a Callable (a Runnable will also work) where I give the input from the process (process.getInputStream ()) and the output where I want to store the output. The same should be done for the StdErr. The resulting output can be read using whatever you like.

 public Object call () throws IOException {
        int bytesRead;
        byte[] b = new byte [ this.maxBlockSize ];

        try {
            while ( ( bytesRead = this.input.read ( b ) ) != -1 ) {
                this.output.write ( b, 0, bytesRead );
            }
        } finally {
            if ( this.output != null ) {
                this.output.close ();
            }
        }
        return null;
    }