[网络协议]TCP实现消息传输和文件传输，UDP实现消息发送和聊天，URL下载文件

目录

TCP

消息传输

文件传输

UDP

消息发送

聊天实现

URL

TCP

消息传输

客户端：

package com.company;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class TcpClientDemo01 {
    public static void main(String[] args) {
        Socket socket =null;
        OutputStream os =null;
        try {
              //要知道服务器的地址，端口号
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //创建一个socket链接
             socket = new Socket(serverIP,port);

            //发送消息IO流
             os = socket.getOutputStream();
            os.write("你好".getBytes());
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

服务器端：

package com.company;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class TcpServerDemo01 {
    public static void main(String[] args) {
        ServerSocket serverSocket =null;
        Socket socket=null;
        InputStream is =null;
        ByteArrayOutputStream baos=null;

        try {
            //我得有一个地址
             serverSocket =new ServerSocket(9999);
            //等待连接
            socket = serverSocket.accept();
            //读取客户端的消息
            is = socket.getInputStream();


            //管道流输出
             baos = new ByteArrayOutputStream();
            byte[] buffer =new byte[1024];
            int len;
            while((len = is.read(buffer))!=-1){
                baos.write(buffer,0,len);
                System.out.println(baos.toString());

            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                baos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

文件传输

客户端：

package com.company;

import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class TcpClientDemo01 {
    public static void main(String[] args) {
        Socket socket =null;
        OutputStream os =null;
        InputStream is =null;
        FileInputStream fis =null;
        ByteArrayOutputStream baos =null;
        try {
            //创建一个Socket链接
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            int port = 9999;
             socket = new Socket(serverIP,port);
             //创建一个输出流
             os = socket.getOutputStream();
            //读取文件
            fis=new FileInputStream(new File("src/桌面.jpg"));
            //写出文件
            byte[] buffer = new byte[1024];
            int len;
            while((len=fis.read(buffer))!=-1){
                os.write(buffer,0,len);
            }
            //发送消息
             os = socket.getOutputStream();
            os.write("你好".getBytes());
            //通知服务器我已经结束了
            socket.shutdownOutput();//传输完成
            //确定服务器接收完毕，才能断开连接
             is= socket.getInputStream();
             baos = new ByteArrayOutputStream();
             byte[] buffer2= new byte[1024];
             int len2;
             while((len2 = is.read(buffer2))!=-1){
                 baos.write(buffer2,0,len2);
             }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                baos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

服务器端：

package com.company;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class TcpServerDemo01 {
    public static void main(String[] args) {
        ServerSocket serverSocket =null;
        Socket socket=null;
        InputStream is =null;
        ByteArrayOutputStream baos=null;
        FileOutputStream fos =null;
        OutputStream os= null;
        try {
            //创建服务
             serverSocket =new ServerSocket(9999);
            //监听等待客户端连接
            socket = serverSocket.accept();//阻塞式监听，一直等待客户端链接
            //获取输入流
            is = socket.getInputStream();
            //文件输出
            fos = new FileOutputStream(new File("recive.jpg"));
            byte[] buffer = new  byte[1024];
            int len;
            while((len =is.read(buffer))!=-1 ){
                fos.write(buffer,0,len);
            }
            //通知客户端我接受完毕了
            os = socket.getOutputStream();
            os.write("我接受完毕了，你可以断开了".getBytes());


        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

UDP

消息发送

package com.company.UDP;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

//UDP不需要连接服务器
public class UDPclient {


    public static void main(String[] args) throws IOException {
        //建立一个Socket
        DatagramSocket socket = new DatagramSocket();
        //建立一个包
        String msg = "hello";
        InetAddress localhost =InetAddress.getByName("localhost");
        int port = 9090;
        //参数：数据，数据长度，起始，端口号
        DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);


        //发送包
        socket.send(datagramPacket);

        socket.close();
    }
}

package com.company.UDP;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
//等待客户端链接
public class UDPserver {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket ds =new DatagramSocket(9090);
        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket dp=new DatagramPacket(buffer,0,buffer.length);
        ds.receive(dp);
        System.out.println(new String(dp.getData(),0,dp.getLength()));

        ds.close();

    }
}

聊天实现

一共有四个类：

1.发送信息TalkSend类

package com.company.chat;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class TalkSend implements Runnable{
    DatagramSocket socket =null;
    BufferedReader reader =null;
    private int fromIP;
    private String toIP;
    private int toPort;

    public TalkSend(int fromIP, String toIP, int toPort) {
        this.fromIP = fromIP;
        this.toIP = toIP;
        this.toPort = toPort;
        try{
            socket = new DatagramSocket(fromIP);
            reader = new BufferedReader(new InputStreamReader(System.in));

        }catch (Exception e){
            e.printStackTrace();
        }

    }

    @Override
    public void run() {
        //准备数据
        while (true){
            String data = null;
            try {
                data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress(this.toIP,this.toPort));
                socket.send(packet);
                if (data.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

2.接收信息TalkReceive类

package com.company.chat;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class TalkReceive implements Runnable {
    DatagramSocket socket =null;
    private int port;
    private  String msgf;

    public TalkReceive(int port,String msgf) {
        this.port = port;
        this.msgf = msgf;
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while (true){
             try {
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container,0,container.length);
                socket.receive(packet);

                 System.out.println();
                 //断开连接
                 byte[] data =packet.getData();
                 String rd = new String(data,0,data.length);
                 System.out.println(msgf+":"+rd);
                 if (rd.equals("bye")){
                     break;
                 }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

3.用户1类（学生）TalkStudent

package com.company.chat;

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(8888,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"老师")).start();
    }
}

4.用户2类（老师）TalkTeacher

package com.company.chat;

public class TalkTeacher {
    public static void main(String[] args) {
        new Thread(new TalkSend(9999,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生")).start();
    }
}

URL

? ? ? ? 统一资源定位符：定位互联网上某一个资源

协议：//IP地址:端口/项目名/资源

URL url = new URL("https://www.baidu.com");
        //得到协议名
        url.getProtocol();
        //得到主机ip
        url.getHost();
        //端口号
        url.getPort();
        //文件地址
        url.getPath();
        //得到文件
        url.getFile();

通过URL下载文件：

package com.company;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class Main {

    public static void main(String[] args) throws Exception {
	// write your code here
        URL url = new URL("http://127.0.0.1:8080/songyi/sy.txt");
        //链接资源
        HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
        InputStream is = urlConnection.getInputStream();
        FileOutputStream fileOutputStream = new FileOutputStream("sy.txt");
        
        byte[] buffer = new byte[1024];
        int len;
        while ((len = is.read(buffer))!=-1){
            fileOutputStream.write(buffer,0,len);
        }
        fileOutputStream.close();
        is.close();
        urlConnection.disconnect();//断开连接
    }
}