Java中的网络编程-2

Socket编程：(一般的网络编程)

　　<1> 两个 JAVA 应用程序可通过一个双向的网络通信连接, 实现数据交换, 这个双向链路的一段称为一个 Socket.

　　<2> Socket 通常用来实现 Client-Server 连接.

　　<3> java.net 包中定义的两个类 Socket 和 ServerSocket(阻塞式), 分别用来实现双向连接的 Client 和 Server 端.　

　　<4> 建立连接时, 所需的寻址信息为远程计算机的 IP 地址和端口号(Port number, 2个字节, 65536个端口, 一个应用程序可能有多个端口号)

　　　　TCP端口、UDP端口分开的, 在技术上来讲, 只有TCP才分 Server 、Client.

　　　　每一个有65536个端口, 端口号用来区分同一台机器上的不同应用程序, 一个人占用了某个端口号, 其他人就不能占了.

　　　　自己编写程序的话, 占1024以后的端口号, 1024以前的不要占, 系统可能会随时征用.

　　　　TCP、UDP二者是不一样的.

　　<5> 默认的网页 http 端口为 80端口；

　　　　SMTP(邮件发送)：25端口

　　　　POP3(接收邮件)：110端口

　　<6> 写 TCPserver、TCPclient 程序时, 首先启动 Server, 再启动 Client, 同时写程序, 一起开发.

Demo_1:

Server端：

import java.io.*;
import java.net.*;
public class TCPserver {
	public static void main(String[] args) throws Exception{
		ServerSocket ss = new ServerSocket(6666);
		while(true){
			Socket s = ss.accept();
			System.out.println("A client connect: ");
			DataInputStream dis = new DataInputStream(s.getInputStream());
			System.out.println(dis.readUTF()); //阻塞式(readUTF), 死死地等待
			dis.close();
			s.close();
		}
	}
}

Client端：

import java.net.*;
import java.io.*;
public class TCPclient {
	public static void main(String[] args) throws Exception{
		Socket s = new Socket("192.168.56.1", 6666);
		OutputStream os = s.getOutputStream(); //拿到输出的那根管道, 往里面写
		DataOutputStream dos = new DataOutputStream(os);
		dos.writeUTF("Hello Server");
		dos.flush();
		dos.close();
		s.close();
	}
}

运行结果：

A client connect:

Hello Server

Demo_2:

Server端：

import java.net.*;
import java.io.*;
public class TestServer {
	public static void main(String[] args) {
		try {
			Socket s1 = new Socket("192.168.56.1", 8888);
			InputStream is = s1.getInputStream();
			DataInputStream dis = new DataInputStream(is);
			System.out.println(dis.readUTF());
			dis.close();
			s1.close();
		} catch (UnknownHostException e) {
			e.printStackTrace();
			System.out.println("错误端口号, 请核对------");
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

Client端：

import java.net.*;
import java.io.*;
public class TestClient {
	public static void main(String[] args) {
		try {
			ServerSocket ss = new ServerSocket(8888);
			while(true){
				Socket s1 = ss.accept();
				OutputStream os = s1.getOutputStream();
				DataOutputStream dos = new DataOutputStream(os);
				dos.writeUTF("Hello, "+s1.getInetAddress()+"Port#, "+s1.getPort()+"Bye--Bye");
				dos.close();
				os.close();
			}
		} catch (IOException e) {
			e.printStackTrace();
			System.out.println("程序出错啦："+e);
		}

	}
}

运行结果：Hello, /192.168.56.1Port#, 4391Bye--Bye

Demo_3:

import java.net.*;
import java.io.*;
public class TestSockServer {
	public static void main(String[] args) {
		InputStream in = null;
		OutputStream os = null;
		try {
			ServerSocket ss = new ServerSocket(5888);
			Socket socket = ss.accept();
			in = socket.getInputStream();
			os = socket.getOutputStream();
			DataInputStream dis = new DataInputStream(in);
			DataOutputStream dos = new DataOutputStream(os);
			String s = null;
			if((s=dis.readUTF())!=null){
				System.out.println(s);
				System.out.println("From: "+socket.getInetAddress());
				System.out.println("Port: "+socket.getPort());
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

Client端：

import java.net.*;
import java.io.*;
public class TestSockClient {
	public static void main(String[] args) {
		InputStream is = null;
		OutputStream os = null;
		try {
			Socket socket = new Socket("192.168.56.1", 5888);
			is = socket.getInputStream();
			os = socket.getOutputStream();
			DataInputStream dis = new DataInputStream(is);
			DataOutputStream dos = new DataOutputStream(os);
			dos.writeUTF("Hey");
			String s = null;
			if((s = dis.readUTF())!=null){
				System.out.println(s);
			}
			dos.close();
			dis.close();
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

运行结果：

Hey
From: /192.168.56.1
Port: 4531

Demo_4:

Server 端：

import java.net.*;
import java.io.*;
public class TalkServer {
	public static void main(String[] args) {
		try {
			ServerSocket server = new ServerSocket(4702);
			Socket socket = server.accept();
			BufferedReader is = new BufferedReader(new InputStreamReader(socket.getInputStream()));
			BufferedReader sin = new BufferedReader(new InputStreamReader(System.in));
			PrintWriter pw = new PrintWriter(socket.getOutputStream());
			System.out.println("Client: "+is.readLine());
			String line = null;
			line = sin.readLine();
			while(!line.equalsIgnoreCase("Bye")){
				pw.println(line);
				pw.flush();
				System.out.println("Client: "+is.readLine());
				line = sin.readLine();
			}
			is.close();
			pw.close();
			socket.close();
			server.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

Client 端：

import java.net.*;
import java.io.*;
public class TalkClient {
	public static void main(String[] args) {
		try {
			Socket socket = new Socket("192.168.56.1", 4702);
			BufferedReader sin = new BufferedReader(new InputStreamReader(System.in));
			BufferedReader is = new BufferedReader(new InputStreamReader(socket.getInputStream()));
			PrintWriter os = new PrintWriter(socket.getOutputStream());
			String readLine = null;
			readLine = sin.readLine();
			while(!readLine.equalsIgnoreCase("Bye")){
				os.println(readLine);
				os.flush();
				System.out.println("Servber: "+is.readLine());
				readLine = sin.readLine();
			}
			os.close();
			is.close();
			socket.close();
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

运行结果展示：