java-网络编程

网络编程网络通信的要素

如何实现网络的通信？

通信双方的地址：

ip端口号

规则：网络通信的协议

TCP/IP协议

网络编程中的两个主要问题

如何准确的定位到网络上的一台或者多台主机找到主机之后如何进行通信

网络编程中的要素

IP和端口号网络通信协议 udp，tcp IP

ip地址：InetAddress

127.0.0.1（localhost）本机地址ip地址的分类

ipv4/ipv6

IPV4 127.0.0.1，4个字节组成。（2~255）IPV6 fe80::e052:a8e4:6e1a:7829%7，128位公网（互联网） - 私网（局域网）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，用来区分软件规定0~65535端口分类

共有端口 0~1023

HTTP: 80HTTPS: 443FTP: 21Telent: 23 程序注册端口：

Tomcat: 8080MySQL: 3306Oracle: 1521 动态私有：49152~65535

netstat -ano #查看所有的端口
netstat -ano|findstr "8080"#查看指定的端口

通信协议

TCP/IP协议

TCP: 用户传输协议UDP：用户数据报协议 TCP

客户端

1.连接服务器Socket

2.发送消息

byName = InetAddress.getByName("127.0.0.1");
            //2.端口号
            int port = 9999;
            //3.创建一个socket连接
            socket = new Socket(byName,port);
            //4.发送消息 IO流
            outputStream = socket.getOutputStream();
            outputStream.write("你好世界".getBytes(StandardCharsets.UTF_8));

服务器

1.建立服务的端口 ServerSockt

2.等待用户的连接 accept

3.接受用的消息

//1.我得有一个地址
            serverSocket = new ServerSocket(9999);
            //2.等待客户端连接
            accept = serverSocket.accept();//serverSocket的监听
            //3.读取客户端的消息
            inputStream = accept.getInputStream();
            //管道流
            byteArrayOutputStream = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len;
            while ((len = inputStream.read(buffer)) != -1) {
                byteArrayOutputStream.write(buffer,0,len);
            }
            System.out.println(byteArrayOutputStream.toString());

文件上传

服务端

package lesson02;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;

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;
        while ((len = is.read(buffer)) != -1){
            fos.write(buffer,0,len);
        }
        //通知客户端接受完毕
        OutputStream os = socket.getOutputStream();
        os.write("我接收完毕了，你可以断开了".getBytes(StandardCharsets.UTF_8));
        //关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

客户端

package lesson02;
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.Buffer;
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.读取文件
        FileInputStream fis = new FileInputStream(new File("zhoujunjie.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！

        //确定服务器接收完毕，才能够断开连接
        InputStream inputStream = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[2024];
        int len2;
        while ((len2 = inputStream.read(buffer2)) != -1){
            baos.write(buffer2,0,len2);
        }
        System.out.println(baos.toString());
        //5.关闭文件
        baos.close();
        inputStream.close();
        fis.close();
        os.close();
        socket.close();

    }
}

Tomcat

服务器

自定义 STomcat服务器 S：Java后台开发

客户端

自定义 C浏览器 B UDP

不需要连接，需要知道地址

发送消息：

package lesson03;
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();

        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;

        //2.建一个包
        String msg = "Hello";
        //数据，数据的长度起始，要发送给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length,localhost,port);

        //3.发送包
        socket.send(packet);

        //4.关闭流
        socket.close();
    }
}

接收端：

package lesson03;
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);
        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);//接收
        socket.receive(packet);//阻塞接收
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        //关闭链接
        socket.close();
    }
}

循环接收消息

发送端

package 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
        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();
    }
}

接收端

package chat;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);
        //准备接收包裹
        while (true){
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet);//阻塞式接收包裹
            //断开链接
            byte[] data = packet.getData();
            String receiveData = new String(data,0,packet.getLength());
            System.out.println(receiveData);
            if (receiveData.equals("bye")){
                break;
            }
        }
        socket.close();
    }
}

在线咨询（两个人都可以是发送端也可以是接收端）

使用多线程

服务端

package 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 msgFrom;
    public TalkReceive(int port,String msgFrom){
        this.port = port;
        this.msgFrom = msgFrom;
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }
    @Override
    public void run() {

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

客户端

package 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;
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() {
        //准备数据：控制台读取 System.in

        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 (data.equals("bye")){
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }

        }
        socket.close();
    }
}

主类

package chat;

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

package chat;

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

URL下载网络资源

统一资源定位符：定位资源的，定位互联网上的某一个资源

DNS 域名解析将域名映射成IP

协议://ip地址:端口号/项目名/资源

package lesson04;
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("https://s1.music.126.net/style/web2/emt/emoji_85.png");
        //2.连接到这个资源 http
        HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
        InputStream inputStream = urlConnection.getInputStream();
        FileOutputStream fos = new FileOutputStream("emoji_85.png");
        byte[] buffer = new byte[1024];
        int len;
        while ((len = inputStream.read(buffer)) != -1){
            fos.write(buffer,0,len);
        }
        fos.close();
        inputStream.close();
        urlConnection.disconnect();
    }
}

java-网络编程

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