java 获取请求主机名 java获取本机ip地址端口号

获取本机的ip地址

InetAddress 类: 用于标识网络上的硬件资源，表示互联网协议（ip）地址

InetAddress类没有公开的构造函数，需要通过类的一些静态方法获取类的实例。

package socket;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Arrays;

public class TestSocket {
    public static void main(String[] args) {
        try {
            InetAddress address = InetAddress.getLocalHost();

            // 获取主机名和IP地址
            System.out.println(address.getHostName());
            System.out.println(address.getHostAddress());
            // 得到主机名/ip地址
            System.out.println(address);

            // 获取字节数组形式的IP地址
            // byte类型的范围是0-127，超过127则为负数；变为正数，加上256即可
            byte[] bytes = address.getAddress();
            System.out.println(Arrays.toString(bytes));

            // 通过机器名获取InetAddress实例
            // InetAddress address2 = InetAddress.getByName("www.baidu.com");

            // 参数也可以为IP地址
            // 注：如果ip地址不存在，或DNS服务器不允许进行ip地址和域名的映射，则返回该ip地址
            InetAddress address2 = InetAddress.getByName("119.75.218.70");
            System.out.println(address2.getHostAddress());

        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}

使用ping

借助Runtime.getRuntime().exec() 可以运行一个Windows的exe程序。

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class TestSocket {
    public static void main(String[] args) throws IOException {
        Process p = Runtime.getRuntime().exec("ping " + "219.216.87.100" );
        // 字符缓存流/字节流转字符流/字节流（Process对象的标准输出）
        BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
        String line = null;
        StringBuilder sb = new StringBuilder();
        while((line = br.readLine()) != null){
            if(line.length() != 0)
                sb.append(line + "\r\n");
        }
        System.out.println("本次指令返回的消息是： ");
        System.out.println(sb.toString());
    }
}

使用Java自带线程池判断本网段有多少可用的ip地址

package socket;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

public class TestSocket {
    public static void main(String[] args) throws IOException, InterruptedException {

        InetAddress host = InetAddress.getLocalHost();
        String ip = host.getHostAddress();
        String ipRange = ip.substring(0, ip.lastIndexOf("."));
        System.out.println("本机ip地址： " + ip);
        System.out.println("网段是：" + ipRange);

        final List<String> ips = Collections.synchronizedList(new ArrayList<String>());
        ThreadPoolExecutor threadPool = new ThreadPoolExecutor(10, 15, 60, TimeUnit.SECONDS,
                new LinkedBlockingQueue<Runnable>());
        final AtomicInteger number = new AtomicInteger();
        for (int i = 0; i < 255; i++) {
            final String testIP = ipRange + "." + (i + 1);
            threadPool.execute(new Runnable() {

                @Override
                public void run() {
                    boolean reachable = isReachable(testIP);
                    if (reachable)
                        ips.add(testIP);
                    synchronized(number){
                        System.out.println("已经完成："+ number.incrementAndGet() + "个 ip 测试");
                    }
                }
            });
        }
        // 所有线程结束，关闭线程池
        threadPool.shutdown();
        // 等待线程池关闭，但是最多等待1个小时
        if(threadPool.awaitTermination(1, TimeUnit.HOURS)){
            System.out.println("如下ip地址可以连接");
            for(String theip : ips){
                System.out.println("总共有：" + ips.size() + " 个地址");
            }
        }
    }

    private static boolean isReachable(String ip) {
        boolean reachable = false;
        try {
            Process p = Runtime.getRuntime().exec("ping " + ip);
            BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
            String line = null;
            StringBuilder sb = new StringBuilder();
            while((line = br.readLine()) != null){
                if(line.length() != 0){
                    sb.append(line + "\r\n");
                }
            }
            // 当有time出现的时候，就表示连通了
            reachable = sb.toString().contains("time<");
            br.close();
            return reachable;
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }
}