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[网络协议]Java网络编程

网络编程

ip

package inetAddress;

import java.net.InetAddress;
import java.net.UnknownHostException;

//测试ip
public class Demo01 {
    public static void main(String[] args) {
        try {
            //查询本机地址
            InetAddress inetAddress2 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress2);
            InetAddress inetAddress3 = InetAddress.getByName("localhost");
            System.out.println(inetAddress3);
            InetAddress inetAddress4 = InetAddress.getLocalHost();
            System.out.println(inetAddress4);
            //查询网络ip地址
            InetAddress inetAddress1 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress1);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}

端口

端口表示计算机上的一个程序的进程；

不同的进程有不同的端口号，端口号不能冲突，用来区分软件
被规定0~65535
TCP，UDP：两个不同协议的端口号可以相同
端口分类
- 共有端口0~1023
- - HTTP：80
  - HTTPS：443
  - FTP：21
  - Telent：23
- 程序注册端口：1024~49151，分配给用户或程序
- - Tomact：8080
  - MySQL：3306
  - Oracle：1521
- 动态，私有：49152~65535
- ```
netstat -ano #查看所有端口
netstat -ano|findstr"5900"#查看指定端口
tasklist|findstr"...."#查看指定端口的进程
```

package inetAddress;

import java.net.InetSocketAddress;

public class Demo02 {
    public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1",8080);
        InetSocketAddress socketAddress2 = new InetSocketAddress("localhost",8080);
        System.out.println(socketAddress);
        System.out.println(socketAddress2);

        System.out.println(socketAddress.getAddress());
        System.out.println(socketAddress.getHostName());//地址
        System.out.println(socketAddress.getPort());//端口
    }
}

通信协议

网络通信协议：速率，传输码率，代码结构，传输控制…

TCP/IP协议簇：实际上是一组协议，传输层。

重要：

TCP：用户传输协议
UDP：用户数据报协议

出名的协议：

TCP：
IP：网络互连协议

TCP UDP对比

TCP：打电话

连接，稳定
三次握手，四次挥手
客户端，服务端
传输完成，释放连接，效率低

UPD：发短信

不连接，不稳定
客户端，服务端，没有明确的界限
不管有没有准备好，都可以发给你。

TCP

客户端

? 1.连接服务器Socket

? 2.发送消息

package inetAddress.lesson01;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.charset.StandardCharsets;

//客户端
public class TcpClientDemo01 {
    public static void main(String[] args) {

        Socket socket = null;
        OutputStream os = null;
        try {
            //1.要知道服务器的地址,端口号
            InetAddress serverIp = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2.创建一个socket连接
            socket = new Socket(serverIp,port);
            //3.发送消息 IO流
            os = socket.getOutputStream();
            os.write("你好啊".getBytes());


        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (os != null) {
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}

服务器

? 1.建立服务的端口 ServerSocket

? 2.等待用户的连接 accept

? 3.接受用户的消息

package inetAddress.lesson01;

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

//服务端
public class TcpServerDemo01 {
    public static void main(String[] args) {

        ServerSocket serverSocket = null;
        Socket socket = null;
        ByteArrayOutputStream baos = null;
        InputStream is = null;
        try {
            //1.我得有一个地址
            serverSocket = new ServerSocket(9999);
            //2.等待客户端连接过来
            socket = serverSocket.accept();
            //3.读取客户端的消息
            is = socket.getInputStream();
            
            //管道流
            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 {
            //关闭资源
            if (baos != null) {
                try {
                    baos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (serverSocket != null) {
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        }
    }
}

文件上传

package inetAddress.lesson01;

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

public class TcpServerDemo02 {
    public static void main(String[] args) throws Exception {
        //1.创建服务
        ServerSocket serverSocket = new ServerSocket(9000);
        //2.监听客户端的连接
        Socket socket = serverSocket.accept();//阻塞式监听，会一直等待客户端连接
        //3.获取输入流
        InputStream is = socket.getInputStream();
        //4.文件输出
        FileOutputStream fos = new FileOutputStream(new File("receive.jpg"));
        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len = is.read(buffer, 0, len)) != -1) {
            fos.write(buffer,0,len);
        }
        //通知客户端我接收完毕了
        OutputStream os = socket.getOutputStream();
        os.write("接收完毕，可以断开".getBytes());
        //关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

package inetAddress.lesson01;

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

public class TcpClientDemo02 {
    public static void main(String[] args) throws Exception {
        //1.创建一个Socket连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);
        //2.创建一个输出流
        OutputStream os = socket.getOutputStream();
        //3.读文件
        FileInputStream fis = new FileInputStream(new File("touxiang.jpg"));
        //4.写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len = fis.read(buffer)) != -1) {
            os.write(buffer,0,len);
        }
        //通知服务器，我已经结束了
        socket.shutdownOutput();//我已经传输完了
        //确定服务器接受完毕，才能断开连接
        InputStream inputStream = socket.getInputStream();
        //String byte[]
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        byte[] buffer2 = new byte[1024];
        int len2 = 0;
        while ((len2 = inputStream.read(buffer2)) != -1) {
            baos.write(buffer2,0,len);
        }
        System.out.println(baos.toString());

        //5.关闭资源
        baos.close();
        fis.close();
        os.close();
        socket.close();
    }
}

Tomcat

服务端

自定义 S
Tomca服务器 S Java后台开发

客户端

自定义 C
浏览器 B

UDP

发短信：不用连接，需要知道对方的地址！

发送消息

package inetAddress.lesson02;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

//不需要连接服务器
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1.建立一个Socket
        DatagramSocket socket = new DatagramSocket();
        //2.建个包
        String msg = "你好";
        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;

        DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);
        //3.发送包
        socket.send(datagramPacket);
        //4.关闭流
        socket.close();
    }
}

接收端

package inetAddress.lesson02;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

//还是要等待客户端的链接！
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接受数据包
        byte[] bytes = new byte[1024];
        DatagramPacket packet = new DatagramPacket(bytes, 0, bytes.length);
        socket.receive(packet);//阻塞接受
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        //关闭链接
        socket.close();

    }
}

咨询

循环发送消息

package inetAddress.chat;

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

public class UdpSenderDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);
        //准备数据：控制台读取System.in
        while (true) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

            String data = reader.readLine();
            byte[] datas = data.getBytes();
            DatagramPacket packet = new DatagramPacket(datas, 0, datas.length,new InetSocketAddress("localhost",6666));
            socket.send(packet);
            if (datas.equals("bye")) {
                break;
            }
        }
        socket.close();
    }
}

package inetAddress.chat;

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

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);


        while (true) {
            //准备接受包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet);//阻塞式接受包裹
            //断开连接
            byte[] data = packet.getData();
            String receiveData = new String(data, 0, data.length);
            System.out.println(receiveData);
            if (receiveData.equals("bye")) {
                break;
            }

        }
        socket.close();

    }

}

在线咨询：两个人都可以是发送方，也可以是接收方

使用多线程

package inetAddress.chat;

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

public class TalkSend implements Runnable{
    DatagramSocket socket = null;
    BufferedReader reader = null;

    private int fromPort;
    private String toIP;
    private int toPort;

    public TalkSend(int fromPort, String toIP, int toPort) {
        this.fromPort = fromPort;
        this.toIP = toIP;
        this.toPort = toPort;
        try {
            socket = new DatagramSocket(fromPort);
            reader = new BufferedReader(new InputStreamReader(System.in));
        } catch (SocketException e) {
            e.printStackTrace();
        }
        
    }

    @Override
    public void run() {
        while (true) {
            try {
                String 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 (datas.equals("bye")) {
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

package inetAddress.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 mgsFrom;

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

    @Override
    public void run() {

        while (true) {
            //准备接受包裹
            try {
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container,0,container.length);
                socket.receive(packet);//阻塞式接受包裹
                //断开连接
                byte[] data = packet.getData();
                String receiveData = new String(data, 0, data.length);
                System.out.println(mgsFrom+":"+receiveData);
                if (receiveData.equals("bye")) {
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

package inetAddress.chat;

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(7777,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"老师")).start();
    }
}

package inetAddress.chat;

public class TalkTeacker {
    public static void main(String[] args) {
        new Thread(new TalkSend(5555,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生")).start();
    }
}

URL

统一资源定位符：定位资源，定位互联网上的某一种资源

DNS 域名解析 www.baidu.com xxx.x…x…x

就是把域名解析成一个ip

协议：//ip地址：端口/项目名/资源

从指定的地址下载到本地

package inetAddress;

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

public class UrlDown {
    public static void main(String[] args) throws Exception {
        //1.下载地址
        URL url = new URL("http//");

        //2.连接到这个资源 HTTP
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

        InputStream inputStream = urlConnection.getInputStream();

        FileOutputStream fos = new FileOutputStream("123.txt");

        byte[] buffer = new byte[1024];
        int len;
        while ((len = inputStream.read(buffer)) != -1) {
            fos.write(buffer,0,len);//导出这个数据
        }
        fos.close();
        inputStream.close();
        urlConnection.disconnect();//断开连接
    }
}