ch6.txt

精通Java网络编程代码全部

/* 代码6-1
 * Created on 2005-5-14
 */
import java.net.*;
java.io.*;
public class LowPortScanner {
	public static void main(String[] args) {
		String host = "localhost";//设定为本地用户
		if (args.length > 0) {
			host = args[0];
		}
		for (int i = 1; i < 1024; i++) {
			try {
				//获取套接字对象
				Socket s = new Socket(host, i);
				System.out.println("There is a server on port " + i + " of "
					+ host);
			}
			catch (UnknownHostException e) {
				System.err.println(e);//打印出错误信息
				break;
			}
			catch (IOException e) {
				//必须是没有被使用过的端口
			}
		}  
	} 
}

/* 代码6-2
 * Created on 2005-5-14
 */


import java.net.*;
import java.io.*;
public class HighPortScanner {
	public static void main(String[] args) {
		//可以通过设置的参数给出主机名
		String host = "localhost";
		if (args.length > 0) {
			host = args[0];
		}
		try {
			InetAddress theAddress = InetAddress.getByName(host);
			for (int i = 1024; i < 65536; i++) {
				try {
					Socket theSocket = new Socket(theAddress, i);//设定套接字
					System.out.println("There is a server on port "
						+ i + " of " + host);
				}
				catch (IOException e) {
				}
			}
		}
		catch (UnknownHostException e) {
			System.err.println(e);//打印出错误信息
		}
	}
}

/* 代码6-3
 * Created on 2005-5-14
 */

import java.net.*;
import java.io.*;
public class SocketInfo {
	public static void main(String[] args) {
		for (int i = 0; i < args.length; i++) {
			try {
				//获取套接字对象
				Socket theSocket = new Socket(args[i], 80);
				System.out.println("Connected to " +
					theSocket.getInetAddress( )
					+ " on port " + theSocket.getPort( ) + " from port "
					+ theSocket.getLocalPort( ) + " of "
					+ theSocket.getLocalAddress( ));//输出地址信息
			} 
			catch (UnknownHostException e) {
				System.err.println("I can't find " + args[i]);//输出错误信息
			}
			catch (SocketException e) {
				System.err.println("Could not connect to " + args[i]);//输出错误信息
			}
			catch (IOException e) {
				System.err.println(e);
			}
		} 
	} 
} 


/* 代码6-4
 * Created on 2005-5-14
 */

import java.net.*;
import java.io.*;
public class DaytimeClient {
	public static void main(String[] args) {
		String hostname;
		if (args.length > 0) {
			hostname = args[0];
		}
		else {
			//此地址为获取精确时间的地址
			hostname = "tock.usno.navy.mil";
		}
		try {
			Socket theSocket = new Socket(hostname, 13);//获得套接字
			InputStream timeStream = theSocket.getInputStream( );//得到输入流
			StringBuffer time = new StringBuffer( );
			int c;
			while ((c = timeStream.read( )) != -1) time.append((char) c);
			String timeString = time.toString().trim( );//得到时间信息
			System.out.println("It is " + timeString + " at " + hostname);
		}
		catch (UnknownHostException e) {
			System.err.println(e);
		}
		catch (IOException e) {
			System.err.println(e);
		}
	}
}



/* 代码6-5
 * Created on 2005-5-14
 */

import java.net.*;
import java.io.*;
public class EchoClient {
	public static void main(String[] args) {
		//设定本地的主机地址
		String hostname = "localhost";
		if (args.length > 0) {
			hostname = args[0];//设定主机信息
		}
		PrintWriter out = null;
		BufferedReader networkIn = null;
		try {
			Socket theSocket = new Socket(hostname, 7);//设置套接字信息
			networkIn = new BufferedReader(
				new InputStreamReader(theSocket.getInputStream( )));
			BufferedReader userIn = new BufferedReader(
				new InputStreamReader(System.in));//通过修饰类装饰输入流
			out = new PrintWriter(theSocket.getOutputStream( ));//输出流
			System.out.println("Connected to echo server");
			while (true) {
				String theLine = userIn.readLine( );//按行读入信息
				if (theLine.equals(".")) break;
				//输出用户输入的信息
				out.println(theLine);
				out.flush( );
				System.out.println(networkIn.readLine( ));
			}
		}
		catch (IOException e) {
			System.err.println(e);//打印错误信息
		}
		finally {
			try {
				if (networkIn != null) networkIn.close( );
				if (out != null) out.close( );
			}
			catch (IOException e) {}
		}
	}
}

/* 代码6-6
 * Created on 2005-5-14
 */

import java.net.*;
import java.io.*;
public class PortScanner {
	public static void main(String[] args) {
		String host = "localhost";
		if (args.length > 0) {
			host = args[0];
		}
		Socket connection = null;
		try {
			//通过主机名获取IP地址
			InetAddress theAddress = InetAddress.getByName(host);
			for (int i = 1; i < 65536; i++) {
				try {
					connection = new Socket(host, i);
					System.out.println("There is a server on port "
						+ i + " of " + host);
				}
				catch (IOException e) {
				}
			}
		} // try的结尾
		catch (UnknownHostException e) {
			System.err.println(e);
		}
		finally {
			try {
				//关闭连接
				if (connection != null) connection.close( );
			}
			catch (IOException e) {}
		}
	} 
} 



/* 代码6-7
 * Created on 2005-5-14
 */

DGSClient.java
// DGSClient.java

import java.io.*;
import java.net.*;

class DGSClient
{
	public static void main (String [] args)
	{
		String host = "localhost";
		// 如果用户给出了字符串，这个字符串表示主机名字
		if (args.length == 1)
			host = args [0];
		DatagramSocket s = null;
		try
		{
			// 在指定的端口上创建DatagramSocket对象
			s = new DatagramSocket ();
			//创建一个字节数组用来保存数据包中的信息，
			byte [] buffer;
			buffer = new String ("Send me a datagram").getBytes ();
			// 将主机名字转变为InetAddress类对象
			// 此对象存有IP 主机的IP地址被DatagramPacket类使用
			InetAddress ia = InetAddress.getByName (host);
			//创建DatagramPacket对象用来封装字节数组的指针以及目标地址的信息。
//此目标地址的信息包含IP地址信息和端口号
			DatagramPacket dgp = new DatagramPacket (buffer,buffer.length,ia,10000);
			// 通过套接字发送数据包
			s.send (dgp);
			// 创建字符数组来保存反馈的信息
			byte [] buffer2 = new byte [100];
			// 创建DatagramPacket对象来构建一个缓冲区
			// 用来保存服务器程序的反馈 
			dgp = new DatagramPacket (buffer2,buffer.length,ia,10000);
			//从套接字中获取数据包
			s.receive (dgp);
			//打印出返回的数据，并保存在数据包中
			System.out.println (new String (dgp.getData ()));
		}
		catch (IOException e)
		{
			System.out.println (e.toString ());
		}
		finally
		{
			if (s != null)
				s.close ();
		}
	}
}  



/* 代码6-8
 * Created on 2005-5-14
 */

// DGSServer.java
import java.io.*;
import java.net.*;

class DGSServer
{
	public static void main (String [] args) throws IOException
	{
		System.out.println ("Server starting ...\n");
		// 在端口10000上创建套接字. 
		//从用户程序发送的包到这个端口
		DatagramSocket s = new DatagramSocket (10000);
		//packet.创建字符数组来保存数据包
		byte [] data = new byte [100];
		//创建数据包对象来封装指针
		//以及字符数组和目的地址信息
		DatagramPacket dgp = new DatagramPacket (data, data.length);
		//进入一个循环，按Ctrl+C为退出
		while (true)
		{
			// 从用户程序接收数据
			s.receive (dgp);
			// 打印数据内容
			System.out.println (new String (data));
			//将同样内容发回
			s.send (dgp);
		}
	}
}



/* 代码6-9
 * Created on 2005-5-14
 */
// MCClient.java
import java.io.*;
import java.net.*;

class MCClient
{
	public static void main (String [] args) throws IOException
	{
		// ll创建MulticastSocket在端口10000上
		//所有的组播数据包都在此端口上接收
		MulticastSocket s = new MulticastSocket (10000);
		InetAddress group = InetAddress.getByName ("231.0.0.1");
		//加入组播组，如此才可以收到数据包
		s.joinGroup (group);
		// 从服务器程序读取数据
		for (int i = 0; i < 10; i++)
		{
			// 任何一行不可以超过256个字符
			byte [] buffer = new byte [256];
			//对象不需要地址信息，因为套接字包含了地址
			DatagramPacket dgp = new DatagramPacket (buffer,
				buffer.length);
			//接收了数据包
			s.receive (dgp)；
				byte [] buffer2 = new byte [dgp.getLength ()];
			//将数据复制到字节数组中
			System.arraycopy (dgp.getData (),0,buffer2,0,dgp.getLength ());
			//打印出来字节数组中的数据
			System.out.println (new String (buffer2));
		}
		//离开组播组
		s.leaveGroup (group);
		//关闭套接字
		s.close ();
	}
}


/* 代码6-10
 * Created on 2005-5-14
 */
// MCServer.java

import java.io.*;
import java.net.*;

class MCServer
{
	public static void main (String[] args) throws IOException
		{
		System.out.println ("Server starting...\n"); 
		//创建一个组播套接字，并不绑定到任何的端口上
			MulticastSocket s = new MulticastSocket ();
			//由于MulticastSocket是DatagramSocket的子类
			// 可以用DatagramSocket s = new DatagramSocket ();
			// 来代替以下的一行
			// MulticastSocket s = new MulticastSocket ();
			InetAddress group = InetAddress.getByName ("231.0.0.1");
			//创建字节数组
			byte [] dummy = new byte [0];
		DatagramPacket dgp = new DatagramPacket (dummy,0,group,10000);
		// 发送3000个字符串到这个端口
			for (int i = 0; i < 30000; i++)
			{
			//从一个字符串上创建字节数组
				byte [] buffer = ("Video line " + i).getBytes ();
			//将这个字符串作为数据包的缓冲
				dgp.setData (buffer);
			//将字符数组的长度作为数据包的缓冲的长度
				dgp.setLength (buffer.length);
			//将数据包发送到整个组播组上
				s.send (dgp);
			}
			//关闭这个套接字
			s.close ();
		}
}