在編寫網管系統的過程中，經常需要判斷某臺機器是否可用，於是採用使用ping機器的方法判斷該機器當前是否可用，方法如下：

/**

 * @Title: execPingCommand

 * @Description: 執行ping命令，檢視裝置是否可用

 * @param @param deviceIp

 * @return boolean true-能ping通，false-不能ping通

 * @throws

*/

public static boolean execPingCommand(String deviceIp) {


logger.debug("enter VolumeManage.execPingCommand(String deviceIp)");


boolean networkUseable = false;


// String address="www.javawind.net";


Process process = null;


try {



process = Runtime.getRuntime().exec("ping -c 3"+ deviceIp);


} catch (IOException e1) {



logger.error("System error:", e1);


}


InputStreamReader r = new InputStreamReader(process.getInputStream());


LineNumberReader returnData = new LineNumberReader(r);



String returnMsg ="";


String line ="";


try {



while ((line = returnData.readLine()) != null) {




// System.out.println(line);




returnMsg += line;



}




if (returnMsg.indexOf("Unreachable") != -1





|| returnMsg.indexOf("100% packet loss") != -1) {




networkUseable = false;



} else {




networkUseable = true;



}


} catch (IOException e) {



logger.error("System error:", e);


} finally {



if (returnData != null) {




try {





returnData.close();





} catch (IOException e) {





// TODO Auto-generated catch block





logger.error("System error:", e);




}



}



if (r != null) {




try {





r.close();




} catch (IOException e) {





// TODO Auto-generated catch block





logger.error("System error:", e);




}



}


}


logger.debug("exit VolumeManage.execPingCommand(String deviceIp)"




+"[networkUseable] ="+ networkUseable);


return networkUseable;

}
 

 此方法關鍵命令為紅色部分：ping -c 3 + ip;這個命令為linux系統所有，windows上不能執行，表示方法執行之後，只需要返回3行響應訊息便可，不然在linux中，如果不終止該命令，會不停的列印響應的訊息。

ping通機器的響應訊息如下：

[[email protected] ~]# ping -c 3 192.168.3.51PING 192.168.3.51 (192.168.3.51) 56(84) bytes of data.64 bytes from 192.168.3.51: icmp_seq=1 ttl=64 time=14.6 ms64 bytes from 192.168.3.51: icmp_seq=2 ttl=64 time=0.332 ms64 bytes from 192.168.3.51: icmp_seq=3 ttl=64 time=0.359 ms

--- 192.168.3.51 ping statistics ---3 packets transmitted, 3 received, 0% packet loss, time 2000msrtt min/avg/max/mdev = 0.332/5.103/14.619/6.728 ms[[email protected] ~]#

ping不同的機器的響應訊息如下：

[[email protected] ~]# ping -c 3 192.168.3.52PING 192.168.3.52 (192.168.3.52) 56(84) bytes of data.From 192.168.7.181 icmp_seq=1 Destination Host Unreachable

--- 192.168.3.52 ping statistics ---3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2000ms, pipe 3[[email protected] ~]#

因此，方法根據這兩個條件進行判斷，如果含有Unreachable或者100% packet loss就表示機器ping不同，不可用，否則為可用。