Distributed System__Java Web Programming Practice

Port(PID)

netstat -ano #查看所有端口
netstat -ano|findstr "6732" #查看指定端口
tasklist|findstr "6732" #查看指定进程
# 使用任务管理器查看PID

端口号与IP地址的组合，得出一个网络套接字:Socket，所以说一些网络编程也被称为Socket编程

import java.net.InetSocketAddress;
public class InetSocketAddressTest {
    public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1",8080);
        InetSocketAddress socketAddress2 = new InetSocketAddress("localhost",9000);
        System.out.println(socketAddress.getHostName());
        System.out.println(socketAddress.getAddress());
        System.out.println(socketAddress.getPort());
        System.out.println(socketAddress2.getHostName()); System.out.println(socketAddress2.getAddress()); //返回地址 System.out.println(socketAddress2.getPort()); //返回端口
    } 
}

Protocal

1. TCP Demo

1.1 Client Demo1

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

//客户端
public class TcpClientDemo01 {
    public static void main(String[] args) {
        Socket socket = null;
        OutputStream os = null;
        try {
            //1. 连接服务器的地址
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            int port = 8899;
            //2. 创建一个Socket
            socket = new Socket(serverIP,port);
            //3. 创建一个输出流，向外写东西
            os = socket.getOutputStream();
            os.write("你好,欢迎学习狂神说Java".getBytes());
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //4. 关闭资源
            try {
                if (os!=null){
                    os.close();
                }
                if (socket!=null){
                    socket.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        } 
    }
}

1.2. Server Demo1

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 accept = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;
        try {
            //1. 开放服务器端口，创建ServerSocket
            serverSocket = new ServerSocket(8899);
            while (true) {
                //2. 等待客户端的连接
                accept = serverSocket.accept();
                //3. 读入客户端的消息,
                is = accept.getInputStream();
                /* 回忆之前的IO流方案，弊端:存在中文，可能存在乱码。 byte[] buffer = new byte[1024];
                int len;
                while ((len=is.read(buffer))!=-1){
                        String str = new String(buffer,0,len);
                        System.out.println(str);
                    }
                **/
                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());
                System.out.println("数据来源地址:"+accept.getInetAddress().getHostName());
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally { //4. 关闭资源
            try {
                if (baos!=null){
                    baos.close();
                }
                if (is!=null){
                    is.close();
                }
                if (accept!=null){
                    accept.close();
                }
                if (serverSocket!=null){
                    serverSocket.close();
                }
            }catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

1.3 Client Demo2

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-10 15:33:20
 * @LastEditTime: 2022-09-11 02:43:36
 * @LastEditors: Zeping Zhu
 * @Description: 
 * @FilePath: /JavaWebPractice/TcpClientDemo02.java
 */
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
public class TcpClientDemo02 {
    public static void main(String[] args) throws Exception {
        // 1. 创建server连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9090);

        // 2. 创建一个输出流
        OutputStream os = socket.getOutputStream();

        // 3. 读取文件
        FileInputStream fis = new FileInputStream(new File("textfile.txt"));

        // 4. 写出文件
        byte[] buffer = new byte[1024];
        int len;
        // file has EOF, so fis.read() will not block
        while ((len = fis.read(buffer)) != -1) {
            os.write(buffer, 0, len);
        }

        // tell server the output stream is over and close output, 
        // otherwise server will always be waiting
        socket.shutdownOutput();
        
        // wait for server to reply, and respond to console
        // System.out.println("I can get there!");
        InputStream inputStream =  socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[1024];
        int len2;
        // Why server doesn't shut down its outputStream but this won't get blocked?
        // because the server will end its function and close, then the inputStream will not block
        while ((len2 = inputStream.read(buffer2)) != -1) {
            baos.write(buffer2, 0, len2);
            // System.out.println("I can get there!");
        }
        System.out.println("I can get there!");
        System.out.println(baos.toString());
        
        // 5. 资源关闭，应该使用try-catch-finally
        baos.close();
        inputStream.close();
        fis.close();
        os.close();
        socket.close();
    }
}

1.4 Server Demo2

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-10 15:33:28
 * @LastEditTime: 2022-09-11 02:40:41
 * @LastEditors: Zeping Zhu
 * @Description: 
 * @FilePath: /JavaWebPractice/TcpServerDemo02.java
 */
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.TimeUnit;
public class TcpServerDemo02 {
    public static void main(String[] args) throws Exception{
        // 1. open serverSocket
        ServerSocket serverSocket = new ServerSocket(9090);

        // 2. listen client socket
        Socket socket = serverSocket.accept();

        // 3. get inputStream
        InputStream is = socket.getInputStream();

        // 4. read file and writer to a new file
        FileOutputStream fos = new FileOutputStream(new File("receive.txt"));
        byte[] buffer = new byte[1024];
        int len;
        // inputStream read is block function, unless outputStream shut down or closed, will always blocked,
        // not even get into the while loop once.
        while ((len = is.read(buffer)) != -1) {
            // System.out.println("I can get there!");
            fos.write(buffer, 0, len);
        }

        System.out.println("I can get there!");

        // tell client receive successfully
        OutputStream outputStream = socket.getOutputStream();
        outputStream.write("File has been received successfully!".getBytes());

        TimeUnit.SECONDS.sleep(1);
        outputStream.write("Can you receive this?".getBytes());
        
        // 5. close, should use try-catch-finally
        outputStream.close();
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

2. UDP Demo

2.1 说明

• DatagramSocket 和 DatagramPacket 两个类实现了基于UDP协议的网络程序。
• UDP 数据报通过数据报套接字 DatagramSocket 发送和接收，系统不保证UDP数据报一定能够安 全送到目的地，也不确定什么时候可以抵达。
• DatagramPacket 对象封装了UDP数据报，在数据报中包含了发送端的IP地址和端口号以及接收端 的IP地址和端口号。
• UDP协议中每个数据报都给出了完整的地址信息，因此无需建立发送方和接收方的连接。如同发快递包裹一样。

2.2 Demo1 Talking

Sender

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

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-10 17:01:23
 * @LastEditTime: 2022-09-10 17:12:10
 * @LastEditors: Zeping Zhu
 * @Description: 
 * @FilePath: /JavaWebPractice/UdpSenderDemo01.java
 */
public class UdpSenderDemo01 {
    public static void main(String[] args) throws Exception{
        System.out.println("Sender start...");
        // 1. create DatagramSocket
        DatagramSocket socket = new DatagramSocket(8888);

        // 2. encapsulate data packet
        // String msg = "Udpsender==>";
        // byte[] data = msg.getBytes();
        // InetAddress inet = InetAddress.getByName("127.0.0.1");
        // int port = 9090;
        // // args: byte[], offset, length, socket(address, port)
        // DatagramPacket packet = new DatagramPacket(data, 0, data.length, inet, port);

        // 2. encapsulate data packet from console input
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        while (true) {
            String data = reader.readLine();
            byte[] datas = data.getBytes();
            // 3. encapsulate datas to DatagramPacket, send to destination
            DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress("localhost", 6666));

            // 4. send packet to receiver
            socket.send(packet);

            // exit check
            if (data.equals("bye")) {
                break;
            }
        }
        // 5. close
        reader.close();
        socket.close();
    }
}

Receiver

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-10 17:12:28
 * @LastEditTime: 2022-09-10 17:18:21
 * @LastEditors: Zeping Zhu
 * @Description: 
 * @FilePath: /JavaWebPractice/UdpReceiverDemo01.java
 */
import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class UdpReceiverDemo01 {
    public static void main(String[] args) throws Exception{
        DatagramSocket socket= new DatagramSocket(6666);
        while(true) {
            try {
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);
                socket.receive(packet); // receive packet(block)
                byte[] datas = packet.getData();
                int len = packet.getLength();
                String data = new String(datas, 0, len);
                System.out.println(data);
                // exit check 
                if (data.equals("bye")) {
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

2.3 Demo2 Multi-thread Talking

SenderThread

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-10 23:01:28
 * @LastEditTime: 2022-09-10 23:09:24
 * @LastEditors: Zeping Zhu
 * @Description: 
 * @FilePath: /JavaWebPractice/TalkSend.java
 */
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class TalkSend implements Runnable {
    private DatagramSocket socket;
    private BufferedReader reader;
    private String toIp;
    private int toPort;

    public TalkSend(int port, String toIp, int toPort) {
        this.toIp = toIp;
        this.toPort = toPort;
        try {
            socket = new DatagramSocket(port);
            reader =new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception 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 (data.equals("bye")) {
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

ReceiverThread

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-10 22:24:18
 * @LastEditTime: 2022-09-10 23:01:08
 * @LastEditors: Zeping Zhu
 * @Description: 
 * @FilePath: /JavaWebPractice/TalkReceive.java
 */
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class TalkReceive implements Runnable {
    private DatagramSocket socket;
    private String msgFrom;
    
    public TalkReceive(int port, String msgFrom) {
        this.msgFrom = msgFrom;
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

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

                byte[] datas = packet.getData();
                int len = packet.getLength();
                String data = new String(datas, 0, len);
                System.out.println(msgFrom + ":" + data + " from address: " + packet.getAddress());
                // exit check
                if (data.equals("bye")) {
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

Student

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-10 23:09:43
 * @LastEditTime: 2022-09-10 23:20:04
 * @LastEditors: Zeping Zhu
 * @Description:
 * @FilePath: /JavaWebPractice/TalkStudent.java
 */
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();
    }
}

Teacher

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-10 23:10:56
 * @LastEditTime: 2022-09-10 23:12:09
 * @LastEditors: Zeping Zhu
 * @Description: 
 * @FilePath: /JavaWebPractice/TalkTeacher.java
 */
public class TalkTeacher {
    public static void main(String[] args) {
        new Thread(new TalkReceive(9999, "学生")).start();
        new Thread(new TalkSend(5555, "localhost", 8888)).start();
    }
}

URL

URL (Uniform Resource Locator): 统一资源定位符，它表示 internet 上某一资源的地址。 它是一种具体的URI，即URL可以用来标识一个资源，而且还指明了如何locate:定位这个资源。 通过URL, 我们可以访问Internet上的各种网络资源，比如最常见的 www, ftp 站点。浏览器通过解析给定的URL可以在网络上查找相应的文件或其他资源。 URL的基本结构由5部分组成:

传输协议://主机名:端口号/文件名 #片段名?参数列表

URL Demo

/*
 * @Author: Zeping Zhu
 * @Andrew ID: zepingz
 * @Date: 2022-09-11 00:30:43
 * @LastEditTime: 2022-09-11 00:47:45
 * @LastEditors: Zeping Zhu
 * @Description: 
 * @FilePath: /JavaWebPractice/URLDemo01.java
 */
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class URLDemo01 {
    public static void main(String[] args) {
        try {
            // 1. locate to ressource of server
            URL url = new URL("https://p1.music.126.net/7DYwgmJyEoTJZ3pyr7lixw==/109951167430870270.jpg?param=40y40");
            System.out.println(url.getProtocol()); //获取URL的协议名
            System.out.println(url.getHost()); //获取URL的主机名
            System.out.println(url.getPort()); //获取URL的端口号
            System.out.println(url.getPath()); //获取URL的文件路径
            System.out.println(url.getFile()); //获取URL的文件名
            System.out.println(url.getQuery()); //获取URL的查询名

            // 2. create connect
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            // 3. get inputStream
            InputStream is = connection.getInputStream();
            
            // 4. write in file
            FileOutputStream fos = new FileOutputStream("icon.png");
            byte[] buffer = new byte[1024];
            int len;
            while ((len = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len);
            }
            // close
            
            fos.close();
            is.close();
            connection.disconnect();
            System.out.println("closed...");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}