網路通訊的要素

阿新 • • 發佈：2020-08-10

網路通訊的要素

網路通訊的要素

1. IP地址

InetAddress

唯一定位一臺網路上的計算機
127.0.0.1：本機 localhost
IP地址的分類
- IPV4/IPV 6
  - IPV4：127.0.0.1 4個位元組組成，0-255，42億個；30億都在北美，亞洲4億
  - IPV6：128位。8個無符號整數（十六進位制，abcde）
```
2001:0bb2:aaaa:0015:0000:0000:1aaa:1312
 
```
- 公網（網際網路）-私網（區域網）
- 192.168.XX.XX 專門給組織內部使用的
- ABCD類地址
域名：解決記憶IP問題

2. Java中的InetAddress包

package com.wang.lesson01;

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

/**
 * @author wang
 * @creatTime 2020/8/7
 */
//測試IP
public class Test01 {
    public static void main(String[] args) {
        //快捷鍵 clt+alt+t
        try {
            //查詢本機地址
            InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress1);
            InetAddress inetAddress3 = InetAddress.getByName("localhost");
            System.out.println(inetAddress3);
            InetAddress inetAddress4 = InetAddress.getLocalHost();
            System.out.println(inetAddress4);

            //查詢網站IP地址
            InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress2);

            //常用方法
            //System.out.println(inetAddress2.getAddress());
            System.out.println(inetAddress2.getCanonicalHostName());    //規範的名字
            System.out.println(inetAddress2.getHostAddress());          //ip
            System.out.println(inetAddress2.getHostName());             //域名，或者本機的名字

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

3. 埠

埠表示計算機上的一個程式的程序

不同的程序有不同的埠號！用來區分軟體！
被規定為0~65535
TCP，UDP：單個協議下，埠號不能衝突

埠分類

共有埠0~1023
- HTTP：80
- HTTPS：443
- FTP：21
- Telent：23
程式註冊埠：1024~49151，分配給使用者或者程式
- Tomcat：8080
- MySQL：3306
- Orale：1521
動態、私有：49152~65535

netstat -ano	#檢視所有的埠
netstat -ano|findstr "5900"	#檢視指定的埠
tasklist|findstr "8696"	#檢視指定埠的程序
Ctrl + Shift + Esc	#開啟工作管理員

package com.wang.lesson01;

import java.net.InetSocketAddress;

/**
 * @author wang
 * @creatTime 2020/8/7
 */
public class TestIntSocketAddress {
    public static void main(String[] args) {

        InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 8080);
        System.out.println(inetSocketAddress.toString());
        InetSocketAddress inetSocketAddress2 = new InetSocketAddress("localhost", 8080);
        System.out.println(inetSocketAddress2.toString());

        System.out.println(inetSocketAddress.getAddress());
        System.out.println(inetSocketAddress.getHostName());    //地址
        System.out.println(inetSocketAddress.getPort());        //埠
    }
}

4. 通訊協議

協議：約定

網路通訊協議：速率，傳輸位元速率，程式碼結構，傳輸控制

問題：複雜

解決方法：大事化小---->分層

TCP/IP協議簇：實際上是一種協議

重要

TCP：使用者傳輸協議
UDP：使用者資料報協議

出名的協議

TCP
IP：網路互連協議

TCP UDP對比

TCP：打電話

連線，穩定
三次握手，四次揮手
客戶端，服務端
傳輸完成，釋放連線，效率低

UDP：發簡訊

不連線，不穩定
客戶端，服務端：沒有明確的界限
不管有沒有準備好，都可以發給你
類比：導彈
DDOS：飽和攻擊

5. TCP

1. 客戶端

連線伺服器Socket
傳送訊息

package com.wang.lesson02;

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

/**
 * @author wang
 * @creatTime 2020/8/7
 */
//客戶端
public class TCPClientDemo01 {
    public static void main(String[] args) {
        Socket socket = null;
        OutputStream os = null;
        try {
            //1.要知道伺服器的地址
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            //2. 埠號
            int port = 9999;
            //3. 建立一個socket連線
            socket = new Socket(serverIP, port);
            //4. 傳送訊息IO流
            os = socket.getOutputStream();
            os.write("這是一行字".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();
                }
            }
        }
    }
}

2. 伺服器

建立服務端的埠
等待使用者的連線accept()，返回客戶的socket
接收使用者的訊息

package com.wang.lesson02;

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

/**
 * @author wang
 * @creatTime 2020/8/7
 */
//服務端
public class TCPServerDemo01 {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;
        try {
            //1. 我得有一個地址
            serverSocket = new ServerSocket(9999);
            //2. 等待客戶端連線過來
            socket = serverSocket.accept();
            //3. 讀取客戶端的訊息
            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 {
            //關閉資源
            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();
                }
            }
        }

    }
}

3. 檔案上傳

伺服器端

package com.wang.lesson02;

import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Paths;

/**
 * @author wang
 * @creatTime 2020/8/7
 */
public class TCPServerDemo02 {
    public static void main(String[] args) throws Exception{
        //1.建立服務
        ServerSocket serverSocket = new ServerSocket(9999);
        //2.監聽客戶端的連線
        Socket socket = serverSocket.accept();//阻塞式監聽，會一直等待客戶端連線
        //3.獲取輸入流
        InputStream is = socket.getInputStream();

        //4.檔案輸出，由於同名的檔案存在時會丟擲異常，因此先刪除同名檔案
        try{
            Files.delete(Paths.get("pic_receive.jpg"));
            Files.copy(is, Paths.get("pic_receive.jpg"));
        } catch (NoSuchFileException e) {
            //如果同名檔案不存在，則在NoSuchFileException中直接複製
            Files.copy(is, Paths.get("pic_receive.jpg"));
        }

        //通知客戶端我接收完畢了
        OutputStream os = socket.getOutputStream();
        os.write("我接收完畢了，你可以斷開了".getBytes());

        is.close();
        socket.close();
        serverSocket.close();
    }
}

客戶端

package com.wang.lesson02;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * @author wang
 * @creatTime 2020/8/7
 */
public class TCPClientDemo02 {
    public static void main(String[] args) throws Exception{
        //1. 建立一個socket連線
        Socket socket = new Socket(InetAddress.getByName("localhost"), 9999);
        //2. 建立一個輸出流
        OutputStream os = socket.getOutputStream();

        //檔案流 Files用copy寫到輸入輸出流，用readAllXXX讀進來
        //3. 讀取檔案
        Path filePath = Paths.get("pic.jpg");

        //4. 寫出檔案
        Files.copy(filePath, os);

        //通知伺服器，我已經結束了
        socket.shutdownOutput();    //我已經傳輸完了

        //確定伺服器接收完畢，才能斷開連線
        InputStream inputStream = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        byte[] buffer = new byte[1024];
        int len;
        while ((len = inputStream.read(buffer)) != -1){
            baos.write(buffer,0,len);
        }

        System.out.println(baos.toString());

        //5.關閉資源
        baos.close();
        inputStream.close();
        os.close();
        socket.close();
    }
}

6. Tomcat

服務端

自定義 S
Tomcat S：Java後臺開發

客戶端

自定義 C
瀏覽器 B

7. UDP

發簡訊：不用連線，需要知道對方的地址！

1. UDP實現傳送訊息

package com.wang.lesson03;

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

/**
 * @author wang
 * @creatTime 2020/8/10
 */

//不需要連線伺服器
public class UDPClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1.建立一個socket
        DatagramSocket socket = new DatagramSocket();

        //2.建個包
        String msg = "Hello, Server!";

        //傳送給誰
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;

        //資料，資料的長度起始，要傳送給誰
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);

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

        //4.關閉流
        socket.close();
    }
}

UDP實現接收訊息

package com.wang.lesson03;

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

/**
 * @author wang
 * @creatTime 2020/8/10
 */
//還要等待客戶端的連線
public class UDPServerDemo01 {
    public static void main(String[] args) throws Exception {
        //開放埠
        DatagramSocket socket = new DatagramSocket(9090);
        //接收資料包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);

        socket.receive(packet); //阻塞接收

        //關閉連線
        socket.close();

        //public String(byte[] bytes,int index,int length) 把位元組陣列的一部分轉成字串
        System.out.println(new String(packet.getData(), 0, packet.getData().length));
    }
}

2. 諮詢

迴圈傳送訊息

package com.wang.chat;

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

/**
 * @author wang
 * @creatTime 2020/8/10
 */
public class UDPSenderDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);

        //準備資料：控制檯讀取System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            String data = reader.readLine();
            byte[] dataBytes = data.getBytes();

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

            socket.send(packet);

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

        socket.close();

    }
}

迴圈接收訊息

package com.wang.chat;

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

/**
 * @author wang
 * @creatTime 2020/8/10
 */
public class UDPReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);

        while (true) {
            //準備接收包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container, 0, container.length);

            socket.receive(packet); //阻塞式接收包裹

            //當接收到"bye"，斷開連線
            byte[] data = packet.getData();
            String receiveData = new String(data, 0, data.length);
            System.out.println(receiveData);
            if (receiveData.equals("bye"))
                break;
        }

        socket.close();
    }
}

3. 線上諮詢

兩個人都可以是傳送方，也都可以是接收方：使用多執行緒

迴圈傳送訊息

package com.wang.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;

/**
 * @author wang
 * @creatTime 2020/8/10
 */
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 (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {

        //準備資料：控制檯讀取System.in
        while (true) {
            try {
                String data = reader.readLine();
                byte[] dataBytes = data.getBytes();

                DatagramPacket packet = new DatagramPacket(dataBytes, 0, dataBytes.length, new InetSocketAddress(this.toIP, this.toPort));

                socket.send(packet);

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

        socket.close();

    }
}

迴圈接收訊息

package com.wang.chat;

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

/**
 * @author wang
 * @creatTime 2020/8/10
 */
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() {
        try {
            while (true) {
                //準備接收包裹
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);

                socket.receive(packet); //阻塞式接收包裹

                //當接收到"bye"，斷開連線
                byte[] data = packet.getData();
                String receiveData = new String(data, 0, data.length);
                System.out.println(msgFrom + "：" + receiveData);
                if (receiveData.equals("bye"))
                    break;

            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        socket.close();
    }
}

老師端

package com.wang.chat;

/**
 * @author wang
 * @creatTime 2020/8/10
 */
public class TalkTeacher {
    public static void main(String[] args) {
        //開啟兩個執行緒
        new Thread(new TalkSend(5555, "localhost", 8888)).start();
        new Thread(new TalkReceive(9999, "學生")).start();
    }
}

學生端

package com.wang.chat;

/**
 * @author wang
 * @creatTime 2020/8/10
 */
public class TalkStudent {
    public static void main(String[] args) {
        //開啟兩個執行緒
        new Thread(new TalkSend(7777, "localhost", 9999)).start();
        new Thread(new TalkReceive(8888, "老師")).start();
    }
}

8. URL

統一資源定位符：定位網際網路上的某一個資源

DNS域名解析：www.baidu.com ===> XXX.XX.XX.X

組成：

協議://ip地址:埠/專案名/資源

可以少但是不能多

package com.wang.lesson04;

import java.net.MalformedURLException;
import java.net.URL;

/**
 * @author wang
 * @creatTime 2020/8/10
 */
public class URLDemo01 {
    public static void main(String[] args) throws MalformedURLException {
        URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=wang&password=123");
        System.out.println(url.getProtocol());      //協議
        System.out.println(url.getHost());          //主機ip
        System.out.println(url.getPort());          //埠
        System.out.println(url.getPath());          //檔案
        System.out.println(url.getFile());          //全路徑
        System.out.println(url.getQuery());         //引數
    }
}

利用URL下載檔案

package com.wang.lesson04;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * @author wang
 * @creatTime 2020/8/10
 */
public class URLDown {
    public static void main(String[] args) throws Exception {
        //1.下載地址
        URL url = new URL("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1597050462137&di=e81d42b6c04eeff13b8011bdcdb7b5e7&imgtype=0&src=http%3A%2F%2Ft8.baidu.com%2Fit%2Fu%3D1484500186%2C1503043093%26fm%3D79%26app%3D86%26f%3DJPEG%3Fw%3D1280%26h%3D853");

        //2.連線到這個資源 用Http
        HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();

        InputStream inputStream = urlConnection.getInputStream();

        //利用Path和Files簡化檔案的IO
        String filePath = "download_pic.jpg";
        Path path = Paths.get(filePath);
        //考慮到可能存在同名檔案，先刪除同名檔案，再copy
        try {
            Files.delete(path);
            Files.copy(inputStream, path);
        } catch (NoSuchFileException e) {
            //不存在同名檔案，會丟擲NoSuchFileException，此時直接copy
            Files.copy(inputStream, path);
        }

        inputStream.close();
    }
}