java 运行时执行 python 脚本 raw_input

Question

我有一个运行 python 脚本的 java 程序（该脚本不是我的，因此无法更改）。我是运行脚本：

Process p = Runtime.getRuntime().exec("python myScript.py");

该脚本有一个 "raw_input" 行需要用户输入。我尝试使用

BufferedWriter userInput = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));
userInput.write("myInput");

但这似乎不起作用；

另一件事，我正在使用

读取输出

BufferedReader stdInput = new BufferedReader(new
                    InputStreamReader(p.getInputStream()));
List<String> output = new ArrayList();
while ((s = stdInput.readLine()) != null) {
                output.add(s);
            }

这在 python 脚本不需要任何输入时起作用，但是当存在 input_raw() 时，stdInput.readLine() 就卡住了。

python 脚本示例：

name = raw_input("What is your name? ")
print "your name is "+name

整个程序：

public static void main(String args[]) {

    PythonRunner pr = new PythonRunner();

    pr.start();

    while(!pr.isFinished){
        try {
            System.out.println("waiting...");
            Thread.sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }


    for(String s:pr.result) System.out.println(s);
}

public class PythonRunner extends Thread {

public List<String> result;
public boolean isFinished;

public PythonRunner() {
    result= new ArrayList<>();
    isFinished = false;
}

@Override
public void run(){
    try {
        Process p = Runtime.getRuntime().exec("python myScript.py");

        BufferedWriter userInput = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));

        BufferedReader stdInput = new BufferedReader(new
                InputStreamReader(p.getInputStream()));

        userInput.write("myInput");

        String s;
        while ((s = stdInput.readLine()) != null) {
             result.add(s);
        }

        isFinished=true;
    }
    catch (IOException e) {
        isFinished=true;
    }

}
}

编辑： 我设法使用

为脚本提供输入

userInput.write(cmd);
userInput.newLine();
userInput.flush();

但是，我仍然无法读取输出。一些脚本有输入-> 打印的无限循环。例如，脚本：

stop = False
while not stop:
    name = raw_input("")
    print "your name is "+name
    if name == "stop":
        stop = True

当这个脚本运行时，我似乎无法读取已经给定名称的输出。只有当进程被赋予 "stop" 命令时，我才能读取整个输出。

Answer 1

你需要继承IO

https://docs.oracle.com/javase/7/docs/api/java/lang/ProcessBuilder.html#inheritIO()

Sets the source and destination for subprocess standard I/O to be the same as those of the current Java process. This is a convenience method. An invocation of the form
pb.inheritIO()

然后，您的流程执行可以采用以下形式

public class ProcessSample {
 public static void main(String [] arg) throws Exception {
   ProcessBuilder pb =
      new ProcessBuilder("python", "script.py").inheritIO();
    Process p = pb.start();
    p.waitFor();
  }
}

并且，使用您的脚本

name = raw_input("What is your name? ")
print "your name is "+name

你可以做到

> javac ProcessSample.java
> java -cp . ProcessSample
What is your name? a
your name is a

正在为 stdout 继承 IO

您始终可以将一些值传递给 Python 代码，同时从标准输出读取值 - 通过继承它。

import java.io.*;

public class PythonProcessRedirect {

  public static void main(String [] arg) throws Exception {

    ProcessBuilder pb =
      new ProcessBuilder("python", "script_raw.py");
    pb.redirectErrorStream(true);
    pb.redirectOutput(ProcessBuilder.Redirect.INHERIT);
    Process p = pb.start();

    BufferedWriter writer = new BufferedWriter( new OutputStreamWriter( p.getOutputStream() ));
    String input = "2\n";
    writer.write(input);
    writer.flush();

    p.waitFor();
  }
}

请注意，对于持续的数据流，您需要刷新它

import sys
import time

sys.stdout.write("give some input: ")
sys.stdout.flush()
time.sleep(2)
line = sys.stdin.readline()
sys.stdout.write("you typed: " + line)
sys.stdout.flush();

否则，数据将在 Python 刷新之前可用（例如，通过将缓冲区填充到限制）。

Stream Gobbler

您还可以使用 Stream Gobbler 和运行单独的线程 stdin/stdout/stderr。

import java.io.*;

public class PythonProcessStreamGobblerIO {

  public static void main(String [] arg) throws Exception {

    final Process p = Runtime.getRuntime().exec("python ./script_os.py" );

    new Thread() {
      public void run() {
        try {
          BufferedWriter writer = new BufferedWriter( new OutputStreamWriter( p.getOutputStream() ));
          String input = "2\n";
          writer.write(input);
          writer.flush();
        } catch(Exception ex) {
          ex.printStackTrace();
        }
      }
    }.start();

    new Thread() {
      public void run() {
        try {
          Reader reader = new InputStreamReader(p.getInputStream());  
          int data = -1;
          while((data =reader.read())!= -1){
            char c = (char) data;
            System.out.print(c);
          }
          reader.close();
        } catch(Exception ex) {
          ex.printStackTrace();
        }
      }
    }.start();

    p.waitFor();
  }
}

但是，同样，您必须确保（在 Python 端）标准输出已刷新。

java 运行时执行 python 脚本 raw_input

java runtime exec a python script with raw_input

python

java

exec

raw-input