《Java TCP/IP Socket编程》读书笔记(2)

2.1 套接字地址

1. 在Java中，地址可以是IP地址也可以是主机名。

下面是一个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 测试 * @author suifeng * */public class InetAddressExample {public static void main(String[] args) {// 获取网络接口和本机关联的地址try {Enumeration<NetworkInterface> interfaceList = NetworkInterface.getNetworkInterfaces();if(interfaceList == null){System.out.println("-----------No networkinterface founded-----------");}else{System.out.println("检查本地网卡设置：");while(interfaceList.hasMoreElements()){// 获取到一块网卡NetworkInterface networkInterface = interfaceList.nextElement();// 获取此网卡的地址Enumeration<InetAddress> addressList = networkInterface.getInetAddresses();// 空列表检测if(!addressList.hasMoreElements()){continue;//System.out.println("\t No address for this interface");}// 数据每一块网卡的名称、IP类型及其地址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();}// 对于从命令行的输入数据打印出主机名及地址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);}}}}

执行结果

InetAddress中有几个重要的方法，使用下面的程序再看一下

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 客户端 *  * @author Suifeng *  */public class UDPEchoClientTimeout{// 超时时间private static final int TIMEOUT = 3000;// 最大连接次数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>]");}// 服务器地址InetAddress serverAddress = InetAddress.getByName(args[0]);// 要发送的数据byte[] byteToSend = args[1].getBytes();// 服务器端口int serverPort = (args.length == 3) ? Integer.parseInt(args[2]) : 7;// UDP客户端DatagramSocket socket = new DatagramSocket();// 接收数据阻塞时间socket.setSoTimeout(TIMEOUT);System.out.println("UDP 客户端已建立....");// 发送数据报包DatagramPacket sendPacket = new DatagramPacket(byteToSend,byteToSend.length, serverAddress, serverPort);// 接收的数据报包DatagramPacket receiverPacket = new DatagramPacket(new byte[byteToSend.length], byteToSend.length);// 尝试接收次数int tries = 0;boolean receivedResponse = false;do{System.out.println("向服务区端发送数据....");// 向服务器端发送数据socket.send(sendPacket);try{System.out.println("接收从服务器端返回的数据...");// 从服务器端接收数据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!");}}}

执行结果