局域网IP扫描器

局域网IP扫描器（简单多线程版）

起因：树莓派烧录系统之后没有显示器，想查找出来同一局域网下的IP

一、获取本机IP

InetAddress host = null;
try {
    host = InetAddress.getLocalHost();
} catch (UnknownHostException e) {
    e.printStackTrace();
    System.out.println("本机网段获取失败");
}

二、截取拼接本机网段

String hostAddress = host.getHostAddress();
System.out.println("本机ip为：" + hostAddress);
String[] split = hostAddress.split("\\.");
String segment = split[0] + "." + split[1] + "." + split[2] + ".";

三、构造ping方法

class pingIP {
    public void ping(String ip){
        try {
            // 模拟cmd
            Process p = Runtime.getRuntime().exec("ping " + ip);
            BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream(),"GBK"));
            while (br.readLine() != null){
                // 如果包含TTL就是成功
                if (br.readLine().contains("TTL")){
                    System.out.println(ip);
                    sb.append(ip);
                }else if (br.readLine().contains("无法访问")){
                    break;
                }
            }

        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("ping方法IO异常");
        }catch (NullPointerException e){
            e.printStackTrace();
            System.out.println("ping方法空指针异常");
        }

    }

}

四、重写run方法

public void run() {
    pingIP pingIP = new pingIP();
    pingIP.ping(ip);
}

五、遍历

for (int i = 0; i < 255; i++) {
    sniffer ss = new sniffer(segment + i);
    new Thread(ss).start();
}

完整项目代码

package TestBasis.lanSniffing;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Scanner;

/**
 * @ClassName: sniffer
 * @Description:
 * @Author: 无心
 * @Date: 2021-02-09 14:24
 * @Version: 1.0
 **/

public class sniffer implements Runnable{
    private StringBuffer sb = new StringBuffer();
    private String ip;

    public sniffer(String ip) {
        this.ip = ip;
    }

    public void run() {
        pingIP pingIP = new pingIP();
        pingIP.ping(ip);
    }

    public static void main(String[] args) {
        System.out.println("获取本机网段中...");

        InetAddress host = null;
        try {
            host = InetAddress.getLocalHost();
        } catch (UnknownHostException e) {
            e.printStackTrace();
            System.out.println("本机网段获取失败");
        }
        String hostAddress = host.getHostAddress();
        System.out.println("本机ip为：" + hostAddress);
        String[] split = hostAddress.split("\\.");
        String segment = split[0] + "." + split[1] + "." + split[2] + ".";
        System.out.println("局域网设备扫描器开始运行，以下ip皆为局域网设备：");
        for (int i = 0; i < 255; i++) {
            sniffer ss = new sniffer(segment + i);
            new Thread(ss).start();
        }


    }

    class pingIP {
        public void ping(String ip){
            try {
                // 模拟cmd的ping
                Process p = Runtime.getRuntime().exec("ping " + ip);
                BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream(),"GBK"));
                while (br.readLine() != null){
                    // 如果包含TTL就是成功
                    if (br.readLine().contains("TTL")){
                        System.out.println(ip);
                        sb.append(ip);
                    }else if (br.readLine().contains("无法访问")){
                        break;
                    }
                }

            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("ping方法IO异常");
            }catch (NullPointerException e){
                e.printStackTrace();
                System.out.println("ping方法空指针异常");
            }

        }

    }
}