實驗3：Internet尋址(解答)
實驗三 Internet 尋址一、實驗?zāi)康?．2．3．4． 熟悉網(wǎng)絡(luò)編程的基本過程 掌握網(wǎng)絡(luò)程序的基本調(diào)試方法 學(xué)習(xí)InetAddress 類的應(yīng)用 理解Internet 尋址的基本概念二、實驗內(nèi)容
實驗三 Internet 尋址
一、實驗?zāi)康?/p>
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4． 熟悉網(wǎng)絡(luò)編程的基本過程 掌握網(wǎng)絡(luò)程序的基本調(diào)試方法 學(xué)習(xí)InetAddress 類的應(yīng)用 理解Internet 尋址的基本概念
二、實驗內(nèi)容
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3． 輸入、調(diào)試、運行一個簡單的網(wǎng)絡(luò)例程，熟悉網(wǎng)絡(luò)編程的過程。 利用InetAddress 類編寫一個能夠獲取本機地址的Java 程序。 利用InetAddress 類編寫一個既能把域名解析為地址的程序，又能把地址解析為域名
的Java 程序。
三、實驗步驟
1． 在Eclipse 中輸入以下兩個程序：
import java.io.*;
import java.net.*;
public class SimpleServer {
public static void main(String[] args) {
try {
ServerSocket ss=new ServerSocket(2007);
Socket s=ss.accept();
Reader in=new InputStreamReader(s.getInputStream());
int c;
while((c=in.read())!=-1){ System.out.write(c);}
} catch (IOException e) {e.printStackTrace();}
}
}
import java.net.*;
import java.io.*;
public class SimpleClient {
public static void main(String[] args) {
try {
Socket s=new Socket("localhost",2007);
Writer out=new OutputStreamWriter(s.getOutputStream());
out.write("Hello,Java network programming!!!n");
out.close();
} catch (UnknownHostException e) {e.printStackTrace(); }
catch (IOException e) {e.printStackTrace(); }
}
}
,2． 按照先運行SimpleServer 后運行SimpleClient 的次序運行這兩個程序，察看結(jié)果。
程序會在服務(wù)器端打?。篐ello,Java network programming!!!
然后客戶端程序與服務(wù)器端程序同時結(jié)束。
3． 然后先運行SimpleClient ，看看有什么結(jié)果。
客戶端將出現(xiàn)： java.net.ConnectException : Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(Unknown Source) at java.net.PlainSocketImpl.connectToAddress(Unknown Source) at java.net.PlainSocketImpl.connect(Unknown Source) at java.net.SocksSocketImpl.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.
4．
5． 利用InetAddress 類編寫一個能夠獲取本機地址的Java 程序，然后運行察看結(jié)果。 輸入下面的程序：
import java.net.InetAddress;
/**
* A command-line utility for performing regular and reverse DNS lookups
*/
public class DNSResolver {
/**
* Expects single argument containing a domain name or dotted decimal
* IP address and outputs the domain-address mappings.
*/
public static void main(String[] args) {
// if (args.length != 1) {
,boolean isReverseLookup = Character.isDigit(str.charAt(0));
try {
InetAddress[] addresses = InetAddress.getAllByName(str);
for(int a=0; a InetAddress address = addresses[a]; if (isReverseLookup) { if (address.getHostAddress().equals(address.getHostName())) { System.out.println("Could not reverse resolve " address.getHostAddress()); } else { System.out.println(address.getHostAddress() " reverse resolves to " address.getHostName()); } } else { System.out.println(address.getHostName() " resolves to " address.getHostAddress()); } } } catch (java.net.UnknownHostException e) { System.err.println("Cannot resolve " str); System.exit(1); } catch (java.lang.SecurityException e) { System.err.println("A security manager has been installed and the" " 'resolve' java.net.SocketPermission has not" " been granted"); System.exit(1); } } } } 在Eclipse 中運行該程序，看看輸入www.baidu.com 、www.microsoft.com 、127.0.0.1等值后，看看是什么結(jié)果。 結(jié)果分別是： www.sina.com.cn resolves to 218.30.66.101 www.microsoft.com resolves to 207.46.19.190 www.microsoft.com resolves to 207.46.193.254 www.microsoft.com resolves to 207.46.192.254 www.microsoft.com resolves to 207.46.19.254 127.0.0.1 reverse resolves to localhost 四、調(diào)試分析 在調(diào)試程序DNSResovler 時，常常會出現(xiàn)異常，后來經(jīng)過仔細(xì)排查后發(fā)現(xiàn)機器沒有連接上Internet ，從而導(dǎo)致程序拋出網(wǎng)絡(luò)連接異常，網(wǎng)絡(luò)連通后可以正確運行。 五、實驗結(jié)果 通過上機，按照實驗指導(dǎo)書操作，得到了題目所要求的實驗結(jié)果。 六、實驗總結(jié) 通過本次實驗，我熟悉了網(wǎng)絡(luò)編程的基本過程，掌握了網(wǎng)絡(luò)程序的基本調(diào)試方法、InetAddress 類的應(yīng)用方法，理解Internet 尋址的基本概念。