獲取指定主機的IP地址

import java.net.InetAddress; import java.net.UnknownHostException;public class GetIP {public static void main(String[] args) {InetAddress address = null;try {address = InetAddress.getByName("www.sanguo.com");}catch (UnknownHostException e) {System.exit(2);}System.out.println(address.getHostName() + "=" + address.getHostAddress());System.exit(0);} }

以上代碼運行輸出結果為：

www.sanguo.com=222.73.134.120

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查看端口是否已使用

import java.net.*; import java.io.*;public class Main {public static void main(String[] args) {Socket Skt;String host = "localhost";if (args.length > 0) {host = args[0];}for (int i = 0; i < 1024; i++) {try {System.out.println("查看 "+ i);Skt = new Socket(host, i);System.out.println("端口 " + i + " 已被使用");}catch (UnknownHostException e) {System.out.println("Exception occured"+ e);break;}catch (IOException e) {}}} }

以上代碼運行輸出結果為：

…… 查看 17 查看 18 查看 19 查看 20 查看 21 端口 21 已被使用 查看 22 查看 23 查看 24 ……

也可以指定主機的端口：

import java.io.IOException; import java.net.InetSocketAddress; import java.net.Socket; import java.net.SocketAddress; import java.net.SocketTimeoutException;public class Main {public static void main(String[] args) {// 檢測本地 80 端口log(isSocketAliveUitlitybyCrunchify("localhost", 80));// 檢測本地 8080 端口log(isSocketAliveUitlitybyCrunchify("localhost", 8080));// 檢測本地 8081 端口log(isSocketAliveUitlitybyCrunchify("localhost", 8081));// 檢測 runoob.com 的 80 端口log(isSocketAliveUitlitybyCrunchify("sanguo.com", 80));// 檢測 runoob.com 的 443 端口log(isSocketAliveUitlitybyCrunchify("sanguo.com", 443));// 檢測 runoob.com 的 81 端口log(isSocketAliveUitlitybyCrunchify("sanguo.com", 81));}/*** 判斷主機端口* * @param hostName* @param port* @return boolean - true/false*/public static boolean isSocketAliveUitlitybyCrunchify(String hostName, int port) {boolean isAlive = false;// 創建一個套接字SocketAddress socketAddress = new InetSocketAddress(hostName, port);Socket socket = new Socket();// 超時設置，單位毫秒int timeout = 2000;log("hostName: " + hostName + ", port: " + port);try {socket.connect(socketAddress, timeout);socket.close();isAlive = true;} catch (SocketTimeoutException exception) {System.out.println("SocketTimeoutException " + hostName + ":" + port + ". " + exception.getMessage());} catch (IOException exception) {System.out.println("IOException - Unable to connect to " + hostName + ":" + port + ". " + exception.getMessage());}return isAlive;}private static void log(String string) {System.out.println(string);}private static void log(boolean isAlive) {System.out.println("是否真正在使用: " + isAlive + "\n");}}

以上代碼運行輸出結果為：

hostName: localhost, port: 80 IOException - Unable to connect to localhost:80. Connection refused 是否真正在使用: truehostName: localhost, port: 8080 IOException - Unable to connect to localhost:8080. Connection refused 是否真正在使用: falsehostName: localhost, port: 8081 IOException - Unable to connect to localhost:8081. Connection refused 是否真正在使用: falsehostName: sanguo.com, port: 80 是否真正在使用: truehostName: sanguo.com, port: 443 是否真正在使用: truehostName: sanguo.com, port: 81 SocketTimeoutException runoob.com:81. connect timed out 是否真正在使用: false

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獲取本機ip地址及主機名

import java.net.InetAddress;public class Main {public static void main(String[] args) throws Exception {InetAddress addr = InetAddress.getLocalHost();System.out.println("Local HostAddress: " + addr.getHostAddress());String hostname = addr.getHostName();System.out.println("Local host name: " + hostname);} }

以上代碼運行輸出結果為：

Local HostAddress: 192.168.1.4 Local host name: harsh

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獲取遠程文件大小

import java.net.URL; import java.net.URLConnection;public class Main {public static void main(String[] args) throws Exception {int size;URL url = new URL("http://www.sanguo.com/wp-content/themes/runoob/assets/img/newlogo.png");URLConnection conn = url.openConnection();size = conn.getContentLength();if (size < 0)System.out.println("無法獲取文件大小。");elseSystem.out.println("文件大小為：" + size + " bytes");conn.getInputStream().close();} }

以上代碼運行輸出結果為：

文件大小為：4261 bytes

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總結

以上是生活随笔為你收集整理的Java 网络实例一（获取指定主机的IP地址、查看端口是否已使用、获取本机ip地址及主机名、获取远程文件大小）的全部內容，希望文章能夠幫你解決所遇到的問題。

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