Question

如何用java实现，实时获取局域网内所有接入设备的IP地址

Answer 1

1.得到局域网网段，可由自己机器的IP来确定 （也可以手动获取主机IP-CMD-ipconfig /all）
2.根据IP类型，一次遍历局域网内IP地址
JAVA类，编译之后直接运行便可以得到局域网内所有IP,具体怎样使用你自己编写相应代码调用便可
代码如下：：
package bean;

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

public class Ip{
static public HashMap ping; //ping 后的结果集
public HashMap getPing(){ //用来得到ping后的结果集
return ping;
}

//当前线程的数量, 防止过多线程摧毁电脑
static int threadCount = 0;

public Ip() {
ping = new HashMap();
}

public void Ping(String ip) throws Exception{
//最多30个线程
while(threadCount>30)
Thread.sleep(50);
threadCount +=1;
PingIp p = new PingIp(ip);
p.start();
}

public void PingAll() throws Exception{
//首先得到本机的IP，得到网段
InetAddress host = InetAddress.getLocalHost();
String hostAddress = host.getHostAddress();
int k=0;
k=hostAddress.lastIndexOf(".");
String ss = hostAddress.substring(0,k+1);
for(int i=1;i <=255;i++){ //对所有局域网Ip
String iip=ss+i;
Ping(iip);
}

//等着所有Ping结束
while(threadCount>0)
Thread.sleep(50);
}

public static void main(String[] args) throws Exception{
Ip ip= new Ip();
ip.PingAll();
java.util.Set entries = ping.entrySet();
Iterator iter=entries.iterator();

String k;
while(iter.hasNext()){
Map.Entry entry=(Map.Entry)iter.next();
String key=(String)entry.getKey();
String value=(String)entry.getValue();

if(value.equals("true"))
System.out.println(key+"-->"+value);
}
}
class PingIp extends Thread{
public String ip; // IP
public PingIp(String ip){
this.ip=ip;
}

public void run(){
try{
Process p= Runtime.getRuntime().exec ("ping "+ip+ " -w 300 -n 1");
InputStreamReader ir = new InputStreamReader(p.getInputStream());
LineNumberReader input = new LineNumberReader (ir);
//读取结果行
for (int i=1 ; i <7; i++)
input.readLine();
String line= input.readLine();

if (line.length() <17 || line.substring(8,17).equals("timed out"))
ping.put(ip,"false");
else
ping.put(ip,"true");
//线程结束
threadCount -= 1;
}catch (IOException e){}
}
}
}