SNMP 简单网关协议获取网络相关信息问题

Question

import java.io.IOException;
import java.net.InetAddress;import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.Snmp;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.UdpAddress;
import org.snmp4j.smi.VariableBinding;
import org.snmp4j.transport.DefaultUdpTransportMapping;
public class TestOp {
public static void main(String[] args)
    {
        try{
            Snmp snmp = new Snmp(new DefaultUdpTransportMapping());
            CommunityTarget target = new CommunityTarget();//agent对象
            target.setCommunity(new OctetString("public"));//设置共同体名,没发现设置RWCommnity的方
                                                           //法,大概只能设一个.
            target.setVersion(SnmpConstants.version2c);//设置版本
            target.setAddress(new UdpAddress("127.0.0.1/161"));//设置IP地址和端口号,这里竟然用'/'来分   
                                                               //隔,当初确实没有料到,JDOC的说明等于没有.
            target.setRetries(3);                      //设置重试次数
            target.setTimeout(5000);             //设置超时
            
            snmp.listen(); 
            PDU request = new PDU();         //new request PDU包
            //set pud type and set oid
            request.setType(PDU.GET);        //设置PDU类型,
            request.add(new VariableBinding(new OID(".1.3.6.1.2.1.7.5.1.1"))); //OID添加
            System.out.println("request UDP:" + request);//请求包内内容输出,
            PDU response = null;//定义response包
            ResponseEvent responseEvent = snmp.send(request, target); //发出request PDU
            //接收response PDU
            response = responseEvent.getResponse();             
                //response PDU包解析
            if(response!=null){
                if(response.getErrorIndex()==response.noError&&response.getErrorStatus()==response.noError){
                    System.out.println("no error.");
                    String pause=responseEvent.getResponse().getVariableBindings().toString();
                    String getvalue=pause.substring( pause.indexOf("= ")+2,pause.indexOf(']'));
                    String oid=pause.substring(pause.indexOf("VBS[")+2,pause.indexOf("=")-1);
                    System.out.println(oid+"::");
                    System.out.println(response);
                    
                }else{
                  System.out.println("get error:"+response.getErrorStatusText());
                }
                
            }else{
                System.out.println("get response error");
            }
            
         
        } catch (IOException e){
            // TODO Auto-generated catch block
            e.printStackTrace();
         
    }
}}  红色代码区，得到的reponse  PDU 是null 所以没有就收到信息，请高手帮忙找找是什么原因导致的

Answer 1

                PDU response = null;//定义response包
[color=#FF0000]                ResponseEvent responseEvent = snmp.send(request, target); //发出request PDU
                //接收response PDU
                response = responseEvent.getResponse();                
                    //response PDU包解析[/color]就是这里的 response 为空！

Answer 2

问题已经解决了 是因为本机没有安装SNMP服务导致的