Java:有没有办法运行系统命令并在执行期间打印输出？

Question

我有一个 python 脚本，需要很长时间才能完成。我想从 Java 运行它，但也在它执行时输出脚本的输出，这样我就可以判断它是否正常运行。

我搜索过，只找到了在系统命令完成后而不是在执行期间输出输出的示例。

有什么方法可以在脚本运行时执行此操作？

这是我的

public void doSomething() throws IOException {
    String[] callAndArgs = {"python", "/hi.py"};
    Process p = Runtime.getRuntime().exec(callAndArgs);
    BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
    BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));

    String s;
    while ((s = stdInput.readLine()) != null) {
        System.out.println(s);
    }

    while ((s = stdError.readLine()) != null) {
        System.out.println(s);
    }
}

Answer 1

我设法让它像这样工作(注意它需要 java7):

package test;
import java.lang.ProcessBuilder.Redirect;

public class Test {

    public static void main(String... args) throws Exception {
        ProcessBuilder pb = new ProcessBuilder("python","/home/foobar/Programming/test/src/test/test.py");
        pb.redirectOutput(Redirect.INHERIT);
        Process p = pb.start();
        p.waitFor();
    }

}

python(注意我在 python 上刷新以使用 sys.stdout.flush() 使其工作)

import time,sys
c =0
while c<=50:
    time.sleep(1)
    print("----")
    c = c +1
    sys.stdout.flush()

注意如果你不想在循环中刷新你可以使用这个:

ProcessBuilder pb = new ProcessBuilder("python","-u","/home/foobar/Programming/NetBeansProjects/test/src/test/test.py");

重定向继承

Indicates that subprocess I/O source or destination will be the same as those of the current process. This is the normal behavior of most operating system command interpreters (shells).