我想获得OutputStream的的Process通过启动exec()到控制台。如何才能做到这一点？

这是一些不完整的代码：

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.Reader;

public class RuntimeTests
{
    public static void main(String[] args)
    {
        File path = new File("C:\\Dir\\Dir2");
        String command = "cmd /c dir";
        Reader rdr = null;
        PrintStream prtStrm = System.out;
        try
        {
            Runtime terminal = Runtime.getRuntime();

            OutputStream rtm = terminal.exec(command, null, path).getOutputStream();
            prtStrm = new PrintStream(rtm);
            prtStrm.println();
        } 
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }
}