Java中的Snmp编程：snmp4j的使用

网管系统基本上都是通过snmp协议来对网络设备进行管理，在Java中，提供了snmp4j.jar这个工具包，来帮助我们方便的实现对网络设备的管理工作，理论上，支持snmp协议的设备，都可以对其状态进行监控，从而获取一些我们需要的信息，或者对设备反馈来的情况进行相应的处理。

声明：此文章是snmp4j初级入门应用，仅作我学习笔记备忘之用，大神请绕行。

在Java中使用snmp4j进行开发时一般要经过下面几个步骤：

1. 创建Snmp对象snmp；
2. 创建CommunityTarget对象target，并指定community,version,address,timeout,retry等参数；
3. 创建PDU对象pdu，并指定操作类型(GET/GETNEXT/GETBULK/SET）,添加VariableBinding（也就是待操作的OID），如果是GETBULK操作，还可以指定MaxRepetitions和NonRepeaters（注意：一定要指定MaxRepetitions，默认是0，那样不会返回任何结果）；
4. 调用snmp.send(pdu,target)方法，发送请求并返回结果;

代码如下：

package org.4spaces;

import java.io.IOException;

import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.Snmp;
import org.snmp4j.TransportMapping;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.smi.Address;
import org.snmp4j.smi.GenericAddress;
import org.snmp4j.smi.Integer32;
import org.snmp4j.smi.Null;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.VariableBinding;
import org.snmp4j.transport.DefaultUdpTransportMapping;
/**
*
* @作者： 四个空格:https://www.4spaces.org
* @功能：Java中进行Snmp编程Demo
* @日期：2014-9-9
*/
public class SnmpDemo2 {
    /**
* 1.创建CommunityTarget对象的方法；
* @param ip
* @param community
* @return
*/
    public static CommunityTarget createDefault(String ip,String community){
Address address = GenericAddress.parse(DEFAULT_PROTOCOL+":"+ip+"/"+DEFAULT_PORT);
//创建target对象
CommunityTarget target = new CommunityTarget();
//指定团体名称community
target.setCommunity(new OctetString(community));
//指定地址address
target.setAddress(address);
//指定版本
target.setVersion(DEFAULT_VERSION);
//指定超时时间
target.setTimeout(DEFAULT_TIMEOUT);
//指定Retry
target.setRetries(DEFAULT_RETRY);
return target;
}

/**
* 2.判断刺探是否结束的方法
* @param targetOID
* @param pdu
* @param vb
* @return
*/
private static boolean checkWalkFinished(OID targetOID, PDU pdu,
VariableBinding vb) {
boolean finished = false;
if (pdu.getErrorStatus() != 0) {
System.out.println("[true] responsePDU.getErrorStatus() != 0 ");
System.out.println(pdu.getErrorStatusText());
finished = true;
}else if(vb.getOid() == null){
System.out.println("[true] vb.getOid() == null");
finished = true;
} else if (vb.getOid().size() < targetOID.size()) {
System.out.println("[true] vb.getOid().size() < targetOID.size()");
finished = true;
} else if (targetOID.leftMostCompare(targetOID.size(), vb.getOid()) != 0) {
System.out.println("[true] targetOID.leftMostCompare() != 0");
finished = true;
} else if (Null.isExceptionSyntax(vb.getVariable().getSyntax())) {
System.out
.println("[true] Null.isExceptionSyntax(vb.getVariable().getSyntax())");
finished = true;
} else if (vb.getOid().compareTo(targetOID) <= 0) {
System.out.println("[true] Variable received is not "
+ "lexicographic successor of requested " + "one:");
System.out.println(vb.toString() + " <= " + targetOID);
finished = true;
}
return finished;
}

/**
* 3.进行刺探的方法
* @param ip
* @param community
* @param targetOid
*/
public static void snmapwalk(String ip, String community, String targetOid){
CommunityTarget target = createDefault(ip, community);
TransportMapping transport = null;
Snmp snmp =null;
try{
transport = new DefaultUdpTransportMapping();
snmp = new Snmp(transport);
transport.listen();
PDU pdu = new PDU();
OID targetOID = new OID(targetOid);
pdu.add(new VariableBinding(targetOID));

boolean finished = false;
System.out.println("Demo Start .....");
while(!finished){
VariableBinding vb = null;
ResponseEvent responseEvent = snmp.getNext(pdu, target);
PDU response = responseEvent.getResponse();
if(null == response){
System.out.println("responsePDU == null ");
finished = true;
break;
}else{
vb = response.get(0);
}
//判断是否结束
finished = checkWalkFinished(targetOID, pdu, vb);
if (!finished) {
System.out.println("==== walk each vlaue :");
System.out.println(vb.getOid() + " = " + vb.getVariable());
// Set up the variable binding for the next entry.
pdu.setRequestID(new Integer32(0));
pdu.set(0, vb);
} else {
System.out.println("SNMP walk OID has finished.");
snmp.close();
}
}
System.out.println("Demo end ....");
}catch(Exception e){
e.printStackTrace();
System.out.println("SNMP walk Exception :" +e);
}finally {
if (snmp != null) {
try {
snmp.close();
} catch (IOException ex1) {
snmp = null;
}
}
}
}

public static void main(String[] args) {
String ip = "127.0.0.1";
String community = "public";
String targetOid = ".1.3.6.1.2.1.1";
SnmpDemo2.snmapwalk(ip, community, targetOid);
}
}

PS:附上完整代码下载地址：点击我开始下载 ；