第7章网络编程7.1.1网络基础7.1.2TCP/IP协议簇7.1.3TCP和UDP7.2InetAdress类7.2InetAdress类publicclassInetAddressTest{publicstaticvoidmain(Stringargs[]){try{InetAddressaddress_1=InetAddress.getByName(“www.sina.com.cn”);//InetAddress类需处理异常System.out.println(address_1.toString());System.out.println(address_1.getHostName());//取InetAddress对象所含的域名。System.out.println(address_1.getHostAddress());//获取InetAddress对象所含的IP地址。InetAddressaddress_2=InetAddress.getLocalHost();//对象含有本地机的域名和IP地址。System.out.println(address_2.toString());}catch(UnknownHostExceptione){System.out.println("www.sina.com.cn");}}使用InetAddress7.2InetAdress类7.3TCP程序设计套接字Socket7.3TCP程序设计7.3TCP网络编程7.3基于Socket的C/S程序对于服务器和客户机而言，将上述第一步改为构造ServerSocket类对象，监听客户端的请求并进行响应。(1)调用ServerSocket(intport)创建一个服务器端套接字，并绑定到指定端口上。(2)调用accept()，监听连接请求，如果客户端请求连接，则接受连接，返回通信套接字。(3)调用Socket类的getOutputStream和getInputStream获取输出流和输入流，开始网络数据的发送和接收。(4)最后关闭通信套接字。图7.1基于Socket的C/S通信7.3TCP网络编程7.3TCP网络编程客户机向服务器发送信息的简单代码PrintWriterout=newPrintWriter(clientSocket.getOutputStream());Stringstr="来自客户机的信息";out.println(str);//将要发送的信息写入out中out.flush();//强制将out中的数据送出clientSocket.close();//关闭连接端口7.3TCP通信程序7.3TCP通信程序7.3TCP网络编程7.3TCP网络编程7.3TCP通信程序7.3TCP通信程序Server和一个客户的对话【例12-3】基于Socket的单客户端程序//客户端程序importjava.awt.*;importjava.awt.event.*;importjavax.swing.*;importjava.io.*;importjava.net.*;publicclassClientDemo{publicstaticvoidmain(Stringargs[]){try{Socketclient=newSocket("127.0.0.1",4000);BufferedReadersin=newBufferedReader(newInputStreamReader(System.in));BufferedReaderis=newBufferedReader(newInputStreamReader(client.getInputStream()));PrintWriteros=newPrintWriter(client.getOutputStream());Stringmsg;msg=sin.readLine();while(!msg.equals("bye")){os.println(msg);os.flush();System.out.println("[ISAY]:"+msg);System.out.println("[ServerSAY]:"+is.readLine());msg=sin.readLine();}System.out.println("TheTalkEnd!");os.close();is.close();client.c