网络网络网络

网络编程

如何准确的定位网络上的一台主机 ip地址：端口定位到这个计算机上的某个资源找到了这个主机，如何传输数据

网络编程的要素

ip 和端口号 IP类网络通信协议 udp类和 tcp类 IP地址

ip类：InetAddress

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

//测试IP
public class netIP {
    public static void main(String[] args) {
        try {
            //查询本机地址
            InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress1);
            InetAddress inetAddress2 = InetAddress.getByName("localhost");
            System.out.println(inetAddress2);
            InetAddress inetAddress3 = InetAddress.getLocalHost();
            System.out.println(inetAddress3);

            //查询网站ip地址
            InetAddress inetAddressb = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddressb);

            //常用方法
            System.out.println(inetAddressb.getAddress());           //返回的是byte
            System.out.println(inetAddressb.getCanonicalHostName());//规范的名字
            System.out.println(inetAddressb.getHostAddress());      //ip
            System.out.println(inetAddressb.getHostName());         //域名，或者自己电脑的名字

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

端口

端口表示计算机上一个程序的进程

不同的进程有不同的端口号，用来区分软件

被规定到0~65535

TCP和UDP各有65535个端口，单个协议下，端口号不能冲突

端口分类

公有端口 0~1023

HTTP ：80HTTPS ：443FTP ：21Telent ：23

程序注册端口 1024~49151 ，分配用户或者程序

Tomcat ：8080MySQL ： 3306Oracle ：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 "8696" #查看指定端口的进程
#ctrl + shift + esc  任务管理器

import java.net.InetSocketAddress;

//测试端口
public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1",8080);
        InetSocketAddress inetSocketAddress2 = new InetSocketAddress("localhost",8080);
        System.out.println(inetSocketAddress);
        System.out.println(inetSocketAddress2);

        System.out.println(inetSocketAddress.getAddress());
        System.out.println(inetSocketAddress.getHostName());
        System.out.println(inetSocketAddress.getHostString());
        System.out.println(inetSocketAddress.getPort());

    }
}

通信协议

协议：约定

网络通信协议

问题：复杂 – > 分层

TCP/IP 协议簇：实际上是一组协议

重要：

TCP ：用户传输协议UDP：用户数据报协议IP：网络互连协议

TCP 和 UDP 对比

TCP 要建立连接三次握手ABA 四次挥手ABBA

UDP不建立连接，不稳定，直接发

TCP

客户端

连接服务器 Socket发送消息

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 TcpClientDemo {
    public static void main(String[] args) {

        Socket socket = null;
        OutputStream os = null;

        try {
            //1.要知道地址,端口号
            InetAddress severIP = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2.创建一个socket连接
            socket = new Socket(severIP,port);
            //3.发送消息IO流
            os = socket.getOutputStream();
            os.write("nsg".getBytes(StandardCharsets.UTF_8));

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

服务器

建立服务的端口 SeverSocket等待用户的连接 accept接收用户消息

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 TcpServerDemo {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;
        try {
            //1.得有一个地址
            serverSocket = new ServerSocket(9999);

            while (true){
                //2.等待客户端连接
                socket = serverSocket.accept();
                //3.读取客户端消息
                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());
            }
//            byte[] buffer = new byte[1024];
//            int len;
//            while ((len = is.read(buffer)) != -1){
//                String msg = new String(buffer, 0, len);
//                System.out.println(msg);
//            }

        } 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

服务器端

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

//文件接收
public class TcpFileServer {
    public static void main(String[] args) throws IOException {
        //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("receive.png");
        byte[] buffer = new byte[1024];
        int len;
        while ((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }

        //通知客户端接收完毕
        OutputStream os = socket.getOutputStream();
        os.write("OK".getBytes());

        //5.关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();

    }
}

客户端

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

//文件上传
public class TcpFileOP {
    public static void main(String[] args) throws IOException {
        //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.读取文件
        FileInputStream fis = new FileInputStream(new File("manman.png"));
        //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，传完了
        socket.shutdownOutput();

        //确定服务器接收完毕，才能关闭
        InputStream is = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

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

        //5.关闭连接
        baos.close();
        is.close();
        fis.close();
        os.close();
        socket.close();
    }
}

Tomcat Udp

发送者

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 UdpSender {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket(8888);

        //准备数据，控制台读取，System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        while (true){
            String data = reader.readLine();
            byte[] datas = data.getBytes();

            DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress("localhost",6666));

            socket.send(packet);
            if(data.equals("bye"))
                break;
        }


        socket.close();
    }
}

接收者

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

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

        while (true){
            //准备接收包裹
            byte[] container = new byte[1024];

            DatagramPacket packet = new DatagramPacket(container,0,container.length);

            socket.receive(packet);

            byte[] data = packet.getData();
            String receiveData = new String(data, 0, packet.getLength());
            System.out.println(receiveData);

            if(receiveData.equals("bye"))
                break;
        }

        socket.close();
    }
}

实时聊天

发送线程

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 toPort;
    private int fromPort;
    private String toIp;

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

    }

    @Override
    public void run() {
        while (true){
            String data = null;
            try {
                data = reader.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            byte[] datas = data.getBytes();

            DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress(this.toIp,this.toPort));

            try {
                socket.send(packet);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if(data.equals("bye"))
                break;
        }
        socket.close();
    }
}

接收线程

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

public class TalkReceive implements Runnable{

    DatagramSocket socket = null;
    private int port;

    public TalkReceive(int port) {
        this.port = port;
        try{
            socket = new DatagramSocket(this.port);
        }catch (Exception e){
            e.printStackTrace();
        }

    }

    @Override
    public void run() {
//        DatagramSocket socket = new DatagramSocket(6666);

        while (true){
            //准备接收包裹
            byte[] container = new byte[1024];

            DatagramPacket packet = new DatagramPacket(container,0,container.length);

            try {
                socket.receive(packet);
            } catch (IOException e) {
                e.printStackTrace();
            }

            byte[] data = packet.getData();
            String receiveData = new String(data, 0, packet.getLength());
            System.out.println(packet.getPort() + ":" + receiveData);

            if(receiveData.equals("bye"))
                break;
        }

        socket.close();
    }
}

the one

public class TalkAn {
    public static void main(String[] args) {
        new Thread(new TalkSend(8848,9949,"localhost")).start();
        new Thread(new TalkReceive(9999)).start();
    }
}

another

public class TalkEx {
    public static void main(String[] args) {
        new Thread(new TalkSend(9999,5555,"localhost")).start();
        new Thread(new TalkReceive(8848)).start();
    }
}

URL

统一资源定位符

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

public class URLZ {
    public static void main(String[] args) throws IOException {
        URL url = new URL("https://space.bilibili.com/95256449/channel/seriesdetail?sid=393820");
        System.out.println(url.getProtocol());  //协议
        System.out.println(url.getHost());      //主机ip
        System.out.println(url.getPort());      //端口
        System.out.println(url.getPath());      //文件
        System.out.println(url.getFile());      //全路径
        System.out.println(url.getQuery());     //参数

        //下载网络资源
        //1.下载地址
        URL urlDownload = new URL("https://img.toy-people.com/member/161588218410.jpg");

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

        InputStream is = urlConnection.getInputStream();                 //得到输入流

        FileOutputStream fos = new FileOutputStream("gaogaigar.jpg");           //写文件

        byte[] buffer = new byte[1024];                                  //缓冲写文件
        int len;

        while((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }

        fos.close();
        is.close();
        urlConnection.disconnect();

    }
}

网络网络网络

Java相关栏目本月热门文章