java 执行系统命令方法

import java.io.*;
import java.util.*;

public class tmp
{
        public static void main(String args[]) throws Exception
        {
                Process proc = Runtime.getRuntime().exec("ls");

                InputStream in = proc.getInputStream();
                DataOutputStream out = new DataOutputStream(System.out);
                byte[] data = new byte[1024];
                int len;
                while (true)
                {
                        len = in.read(data, 0, 1024);
                        if (len == -1)
                                break;
                        out.write(data);
                }
        }
}