《Java TCP/IP Socket編程》讀書筆記(2)

2.1 通訊端地址

1. 在Java中，地址可以是IP地址也可以是主機名稱。

下面是一個Java中地址的例子

package com.suifeng.tcpip.chapter2;import java.net.Inet4Address;import java.net.Inet6Address;import java.net.InetAddress;import java.net.NetworkInterface;import java.net.SocketException;import java.net.UnknownHostException;import java.util.Enumeration;/** * InetAddress 測試 * @author suifeng * */public class InetAddressExample {public static void main(String[] args) {// 擷取網路介面和本機關聯的地址try {Enumeration<NetworkInterface> interfaceList = NetworkInterface.getNetworkInterfaces();if(interfaceList == null){System.out.println("-----------No networkinterface founded-----------");}else{System.out.println("檢查本地網卡設定：");while(interfaceList.hasMoreElements()){// 擷取到一塊網卡NetworkInterface networkInterface = interfaceList.nextElement();// 擷取此網卡的地址Enumeration<InetAddress> addressList = networkInterface.getInetAddresses();// 空列表檢測if(!addressList.hasMoreElements()){continue;//System.out.println("\t No address for this interface");}// 資料每一塊網卡的名稱、IP類型及其地址System.out.println(networkInterface.getName());while(addressList.hasMoreElements()){InetAddress address = addressList.nextElement();System.out.println("\tAddress "+((address instanceof Inet4Address) ? "(IPV4)": (address instanceof Inet6Address) ? "(IPV6)":"(?)" )+"\t"+address.getHostAddress());}}}} catch (SocketException e) {System.out.println("Error get network interface :"+e.getMessage());e.printStackTrace();}// 對於從命令列的輸入資料列印出主機名稱及地址System.out.println("");for(String host : args){System.out.println("Host:"+host);try {InetAddress[] addressList = InetAddress.getAllByName(host);for (InetAddress address : addressList) {System.out.println("\t"+address.getHostName()+"/"+address.getHostAddress());}} catch (UnknownHostException e) {System.out.println("unable to find address for:"+host);}}}}

執行結果

InetAddress中有幾個重要的方法，使用下面的程式再看一下

package com.suifeng.tcpip.chapter2;import java.io.IOException;import java.io.InterruptedIOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;import java.net.SocketException;import java.net.UnknownHostException;/** * UDP 用戶端 *  * @author Suifeng *  */public class UDPEchoClientTimeout{// 逾時時間private static final int TIMEOUT = 3000;// 最大串連次數private static final int MAXTRIES = 5;public static void main(String[] args) throws IOException{if (args.length < 2 || args.length > 3){throw new IllegalArgumentException("Paramters:<Server> <Word> [<Port>]");}// 伺服器位址InetAddress serverAddress = InetAddress.getByName(args[0]);// 要發送的資料byte[] byteToSend = args[1].getBytes();// 伺服器連接埠int serverPort = (args.length == 3) ? Integer.parseInt(args[2]) : 7;// UDP用戶端DatagramSocket socket = new DatagramSocket();// 接收資料阻塞時間socket.setSoTimeout(TIMEOUT);System.out.println("UDP 用戶端已建立....");// 發送資料報包DatagramPacket sendPacket = new DatagramPacket(byteToSend,byteToSend.length, serverAddress, serverPort);// 接收的資料報包DatagramPacket receiverPacket = new DatagramPacket(new byte[byteToSend.length], byteToSend.length);// 嘗試接收次數int tries = 0;boolean receivedResponse = false;do{System.out.println("向服務區端發送資料....");// 向伺服器端發送資料socket.send(sendPacket);try{System.out.println("接收從伺服器端返回的資料...");// 從伺服器端接收資料socket.receive(receiverPacket);if (!receiverPacket.getAddress().equals(serverAddress)){throw new IOException("Received packet from an unknown source");}receivedResponse = true;}catch (InterruptedIOException e){tries++;System.out.println("Timed out," + (MAXTRIES - tries)+ " more ties");}} while ((!receivedResponse) && (tries < MAXTRIES));if(receivedResponse){System.out.println("Received:"+new String(receiverPacket.getData()));}else{System.out.println("No response--giving up!");}}}

執行結果