Runtime.getRuntime().exec执行scp失败

[root@hadron ~]# scp  /root/scripts/* 192.168.1.157:/opt
Step1.sh                                                                                                                                   100%  340     0.3KB/s   00:00    
Step2.sh                                                                                                                                   100%   12     0.0KB/s   00:00    
Step3.sh   

package util;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.net.InetAddress;
import java.net.UnknownHostException;

public class LocalCommand {

    public static final String getIP(){
        try {
            InetAddress ia = InetAddress.getLocalHost();
            return ia.getHostAddress();
        } catch (UnknownHostException e1) {
            e1.printStackTrace();
            return null;
        }
    }
    public static final String exe(String cmd){
        StringBuffer sb=null;
        Process process=null;
        LineNumberReader reader=null;
        try {
            sb = new StringBuffer();
            process=Runtime.getRuntime().exec(cmd);
            reader = new LineNumberReader(new InputStreamReader(process.getInputStream()));
            String line;
            while ((line = reader.readLine()) != null){ 
               sb.append(line+"\n");
            }
            return sb.toString();
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }finally {
            try {
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            process.destroy();
        }
    }
}

package test;

import util.LocalCommand;

public class TestLocal {
    public void test(){
        String rs;
        rs=LocalCommand.exe("scp /root/* 192.168.1.157:/opt/");
        System.out.println(rs);
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        new TestLocal().test(); 


    }

}

public void test(){
        String rs;
        rs=LocalCommand.exe("scp -r /root/scripts/ 192.168.1.157:/opt/");
        System.out.println(rs);
}

[root@node]:/opt/scripts# ls
Step1.sh  Step2.sh  Step3.sh