如何从node.js子进程使用CLI应用程序？

Question

I am wordering how to use application with command line interface from node.js. Here is node.js code:

var spawn = require('child_process').spawn;
var child = spawn('java', ['HelloWorld']);

child.stdout.pipe(process.stdout);
child.stdin.write("tratata\r\n;");

child.stdin.end();

it runs java HelloWorld cli app.

here is java code:

import java.io.Console;

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("started");

        Console console = System.console();

        while (true) {
            String s = console.readLine();
            System.out.println("Your sentence:" + s);
        }
    }
}

but it doesn't work. when child.stdin.write executs - nothing happening.

Answer 1

Disclaimer: I know next to nothing about Java.

My guess is that java.io.Console does a lot more than just reading from stdin, like opening the console device ( /dev/tty on most Unix-like OS'es) itself, thereby circumventing the stdin/stdout/stderr devices being passed in by Node.

If you use java.io.BufferedReader , it works better:

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("started");

        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        while (true) {
            try {
                String s = reader.readLine();
                if (s == null) return; // end of stream reached
                System.out.println("Your sentence:" + s);
            } catch(IOException e) {
            }
        }
    }
}