J2SE之网络编程

网络基础概念

网络通信协议及接口

通信协议分层的思想

参考模型

数据封装

数据拆封

IP协议

TCP协议和UDP协议

Socket

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

public class TCPServer
{
    public static void main(String[] args)throws Exception{
        
        ServerSocket ss = new ServerSocket(6666);
        while (true)
        {
            Socket s = ss.accept();
            DataInputStream dis = new DataInputStream(s.getInputStream());
            System.out.println(dis.readUTF());
            dis.close();
            s.close();
        }
        
    }
}

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

public class TCPClient
{
    public static void main(String[] args) throws Exception{
        Socket s = new Socket("127.0.0.1",6666);
        OutputStream os = s.getOutputStream();
        DataOutputStream dos = new DataOutputStream(os);
        Thread.sleep(3000);
        dos.writeUTF("hello server");
        dos.flush();
        dos.close();
        s.close();
    }
}

TCP Socket 通信模型

举例

/*    范例名称：简单的client/server程序
 *     源文件名称：TestClient.java/TestServer.java
 *    要  点：
 *        1. Java Socket编程步骤
 *        2. Socket/ServerSocket类用法
 *        3. 通过Socket对象可以获取通信对方Socket的信息
 */
import java.net.*;
import java.io.*;

public class TestServer {
    public static void main(String args[]) {
        try {        
            ServerSocket s = new ServerSocket(8888);
            while (true) {
                Socket s1 = s.accept();
                OutputStream os = s1.getOutputStream();
                DataOutputStream dos = new DataOutputStream(os);
                dos.writeUTF("Hello," + s1.getInetAddress() + 
                        "port#" +s1.getPort() + "  bye-bye!");
                dos.close();
                s1.close();
            }
        }catch (IOException e) {
            e.printStackTrace();
            System.out.println("程序运行出错:" + e);            
        }
    }
}

/*    范例名称：简单的client/server程序
 *     源文件名称：TestClient.java/TestServer.java
 *    要  点：
 *        1. Java Socket编程步骤
 *        2. Socket/ServerSocket类用法
 *        3. 通过Socket对象可以获取通信对方Socket的信息
 */

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

public class TestClient {
    public static void main(String args[]) {
        try {
            Socket s1 = new Socket("127.0.0.1", 8888);
            InputStream is = s1.getInputStream();
            DataInputStream dis = new DataInputStream(is);
            System.out.println(dis.readUTF());
            dis.close();
            s1.close();
        } catch (ConnectException connExc) {
            connExc.printStackTrace();
            System.err.println("服务器连接失败！");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

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

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("localhost",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();
      socket.close();
    } catch (UnknownHostException e) {
       e.printStackTrace();
    } catch (IOException e) {e.printStackTrace();}
  }
}

import java.io.*;
import java.net.*;
import java.applet.Applet;
public class talkserver
{
    public static void main(String args[])
    {
        try
        {
            ServerSocket server = null;
            try
            {
                server = new ServerSocket(4700);
            }catch(Exception e)
            {
                System.out.println("can not listen to:" + e);
            }
            Socket socket = null;
            try
            {
                socket = server.accept();
            }catch(Exception e)
            {
                System.out.println("Error:" + e);
            }
            String line;
            BufferedReader is = new BufferedReader(new InputStreamReader(
                socket.getInputStream()));
            PrintWriter os = new PrintWriter(socket.getOutputStream());
            BufferedReader sin = new BufferedReader(new InputStreamReader(System.in));
            System.out.println("Client:" + is.readLine());
            line = sin.readLine();
            while (!line.equals("bye"))    
            {
                os.println(line);
                os.flush();
                System.out.println("Server:" + line);
                System.out.println("Client:" + is.readLine());
                line = sin.readLine();
            }

            is.close();
            os.close();
            socket.close();
            server.close();
        }catch(Exception e)
        {
            System.out.println("Error" + e);
        }
    }
}
            

import java.io.*;
import java.net.*;
public class talkclient
{
    public static void main(String args[])
    {
        try
        {
            Socket socket = new Socket("127.0.0.1",4700);
            BufferedReader sin = new BufferedReader(new InputStreamReader(System.in));
            PrintWriter os = new PrintWriter(socket.getOutputStream());
            BufferedReader is = new BufferedReader(new InputStreamReader(
                socket.getInputStream()));
            String readline;
            readline = sin.readLine();
            while (!readline.equals("bye"))    
            {
                os.println(readline);
                os.flush();
                System.out.println("Client:" + readline);
                System.out.println("Server:" + is.readLine());
                readline = sin.readLine();
            }
            os.close();
            is.close();
            socket.close();
        }catch(Exception e)
        {
            System.out.println("Error" + e);
        }
    }
}
            

 UDP

import java.net.*;

public class TestUDPServer
{
    public static void main(String args[]) throws Exception
    {
        byte buf[] = new byte[1024];
        DatagramPacket dp = new DatagramPacket(buf, buf.length);
        DatagramSocket ds = new DatagramSocket(5678);
        while(true)
        {
            ds.receive(dp);
            System.out.println(new String(buf,0,dp.getLength()));
        }
    }
}

import java.net.*;

public class TestUDPClient
{
    public static void main(String args[]) throws Exception
    {
        byte[] buf = (new String("Hello")).getBytes();
        DatagramPacket dp = new DatagramPacket(buf, buf.length, 
                                               new InetSocketAddress("127.0.0.1", 5678)
                                               );
        DatagramSocket ds = new DatagramSocket(9999);
        ds.send(dp);
        ds.close();
    }
}

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

public class TestUDPServer
{
    public static void main(String args[]) throws Exception
    {
        byte buf[] = new byte[1024];
        DatagramPacket dp = new DatagramPacket(buf, buf.length);
        DatagramSocket ds = new DatagramSocket(5678);
        while(true)
        {
            ds.receive(dp);
            ByteArrayInputStream bais = new ByteArrayInputStream(buf);
            DataInputStream dis = new DataInputStream(bais);
            System.out.println(dis.readLong());
        }
    }
}

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

public class TestUDPClient
{
    public static void main(String args[]) throws Exception
    {
        long n = 10000L;
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        DataOutputStream dos = new DataOutputStream(baos);
        dos.writeLong(n);
        
        byte[] buf = baos.toByteArray();
System.out.println(buf.length);
        
        DatagramPacket dp = new DatagramPacket(buf, buf.length, 
                                               new InetSocketAddress("127.0.0.1", 5678)
                                               );
        DatagramSocket ds = new DatagramSocket(9999);
        ds.send(dp);
        ds.close();
        
    }
}