phase 3;

no,
i am the one who knocks!

src/main/java/server/FileDownloadClient.java

@@ -0,0 +1,38 @@
+package server;
+
+import java.io.*;
+import java.net.Socket;
+import java.util.Scanner;
+
+public class FileDownloadClient {
+    private static final int PORT = 9060;
+    private static final String IP = "127.0.0.1";
+    static DataInputStream in;
+    static DataOutputStream out;
+    static Scanner scanner;
+    private static Socket socket;
+
+    public static void main(String[] args) {
+        scanner = new Scanner(System.in);
+        String name = scanner.nextLine();
+        String path = scanner.nextLine();
+        try {
+            socket = new Socket(IP, PORT);
+            in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
+            out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
+            out.writeUTF("DownloadName:" + name);
+            out.flush();
+            int byteNumber = (int) Double.parseDouble(in.readUTF());
+            byte[] allBytes = new byte[byteNumber];
+            for (int i = 0; i < byteNumber; i++) {
+                allBytes[i] = in.readByte();
+            }
+            FileOutputStream fileOutputStream = new FileOutputStream(path);
+            fileOutputStream.write(allBytes);
+            fileOutputStream.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+}

src/main/java/server/FileServer.java

@@ -0,0 +1,82 @@
+package server;
+
+import java.io.*;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.nio.file.Files;
+
+public class FileServer {
+    public static final int PORT = 9060;
+    private static final String PATH = "src\\main\\resources\\";
+    private DataOutputStream out;
+    private DataInputStream in;
+    private ServerSocket fileServer;
+
+    public FileServer() throws IOException {
+        fileServer = new ServerSocket(PORT);
+        new Thread(new Runnable() {
+            @Override
+            public void run() {
+                while (true) {
+                    try {
+                        Socket socket = fileServer.accept();
+                        in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
+                        out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
+                        new main.java.FileServer.ClientHandler(out, in, socket).start();
+                    } catch (IOException e) {
+                        e.printStackTrace();
+                    }
+                }
+            }
+        }).start();
+    }
+
+    static class ClientHandler extends Thread {
+        private DataOutputStream dataOutputStream;
+        private DataInputStream dataInputStream;
+        private Socket socket;
+
+        private ClientHandler(DataOutputStream dataOutputStream, DataInputStream dataInputStream, Socket socket) {
+            this.dataOutputStream = dataOutputStream;
+            this.dataInputStream = dataInputStream;
+            this.socket = socket;
+        }
+
+        @Override
+        public void run() {
+            try {
+                String input;
+                while (true) {
+                    input = dataInputStream.readUTF();
+                    if (input.startsWith("DownloadName:")) {
+                        int colonIndex = input.indexOf(":");
+                        String fileName = input.substring(colonIndex + 1);
+                        File file = new File(PATH + fileName);
+                        byte[] fileContent = Files.readAllBytes(file.toPath());
+                        dataOutputStream.writeUTF("" + fileContent.length);
+                        dataOutputStream.flush();
+                        for (byte b : fileContent) {
+                            dataOutputStream.write(b);
+                            dataOutputStream.flush();
+                        }
+                        return;
+                    } else if (input.startsWith("UploadName:")) {
+                        String[] parts = input.split(":");
+                        String fileName = parts[1];
+                        int fileByteSize = Integer.parseInt(parts[2]);
+                        byte[] allBytes = new byte[fileByteSize];
+                        for (int i = 0; i < fileByteSize; i++) {
+                            allBytes[i] = dataInputStream.readByte();
+                        }
+                        FileOutputStream fileOutputStream = new FileOutputStream(PATH + fileName);
+                        fileOutputStream.write(allBytes);
+                        fileOutputStream.close();
+                        return;
+                    }
+                }
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}

src/main/java/server/FileUploadClient.java

@@ -0,0 +1,38 @@
+package server;
+
+import java.io.*;
+import java.net.Socket;
+import java.nio.file.Files;
+import java.util.Scanner;
+
+public class FileUploadClient {
+    private static final int PORT = 9060;
+    private static final String IP = "127.0.0.1";
+    static DataInputStream in;
+    static DataOutputStream out;
+    static Scanner scanner;
+    private static Socket socket;
+
+
+    public static void main(String[] args) {
+        scanner = new Scanner(System.in);
+        String name = scanner.nextLine();
+        String location = scanner.nextLine();
+        try {
+            socket = new Socket(IP, PORT);
+            in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
+            out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
+            File file = new File(location + name);
+            byte[] fileContent = Files.readAllBytes(file.toPath());
+            out.writeUTF("UploadName:" + name + ":" + fileContent.length);
+            out.flush();
+            for (byte b : fileContent) {
+                out.write(b);
+                out.flush();
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+}