Chapter 19 - 네트워크 입출력 확인문제

Chapter 19 - 네트워크 입출력 확인문제

정답: 2

클라이언트가 서버에 연결하기 위해서는 IP 주소와 Port 번호가 있어야 한다.

정답: 2, 4

2: TCP -> UDP
4: UDP -> TCP

정답:

new Socket("localhost", 5001);

serverSocket.accept()

정답:

좌상단 -> 우상단 -> 좌하단 -> 우하단

InputStream

OutputStream

OutputStream

InputStream

정답:

1. DatagramSocket
2. DatagramPacket
3. DatagramSocket
4. DatagramPacket
5. DatagramPacket
   

정답: 4

클라이언트로 DatagramPacket을 발신할 때 send() 메소드를 사용한다.

import java.util.Objects;


public class Product {
    public Product() {
    }

    public Product(int no, String name, int price, int stock) {
        this.no = no;
        this.name = name;
        this.price = price;
        this.stock = stock;
    }

    public int getNo() {
        return no;
    }

    public void setNo(int no) {
        this.no = no;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Product product = (Product) o;
        return no == product.no && price == product.price && stock == product.stock && name.equals(product.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(no, name, price, stock);
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }

    public int getStock() {
        return stock;
    }

    public void setStock(int stock) {
        this.stock = stock;
    }

    @Override
    public String toString() {
        return "Product{" + "no=" + no + ", name='" + name + '\'' + ", price=" + price + ", stock=" + stock + '}';
    }

    private int no;
    private String name;
    private int price;
    private int stock;
}

import org.json.JSONArray;
import org.json.JSONObject;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.TreeMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ProductServer {
    private int pk;
    private TreeMap<Integer, Product> products;
    private ExecutorService es;

    public static void main(String[] args) {
        ProductServer productServer = new ProductServer();
        try {
            productServer.start();
        } catch (IOException ignored) {
        }
    }


    public void start() throws IOException {
        try (ServerSocket ss = new ServerSocket(50001)) {
            es = Executors.newFixedThreadPool(100);
            products = new TreeMap<>();
            System.out.println("[서버] 시작됨");
            while (true) {
                try {
                    new SocketClient(ss.accept());
                } catch (IOException e) {
                    break;
                }
            }
        }
    }

    public class SocketClient {
        private Socket sc;
        private DataInputStream dis;
        private DataOutputStream dos;

        public SocketClient(Socket sc) {
            try {
                this.sc = sc;
                this.dis = new DataInputStream(sc.getInputStream());
                this.dos = new DataOutputStream(sc.getOutputStream());
                receive();
            } catch (IOException e) {
                try {
                    sc.close();
                } catch (IOException ignored) {
                }
            }
        }

        public void receive() {
            es.execute(() -> {
                while (true) {
                    try {
                        JSONObject requestJson = new JSONObject(dis.readUTF());
                        int menu = requestJson.getInt("menu");
                        switch (menu) {
                            case 0 -> getProductList();
                            case 1 -> createProduct(requestJson);
                            case 2 -> updateProduct(requestJson);
                            case 3 -> deleteProduct(requestJson);
                        }
                    } catch (IOException e) {
                        break;
                    }
                }

                try {
                    sc.close();
                } catch (IOException ignored) {
                }
            });
        }

        public void getProductList() throws IOException {
            JSONArray productList = new JSONArray();
            JSONObject product;
            JSONObject jsonResponse = new JSONObject();

            for (Product p : products.values()) {
                product = new JSONObject();
                product.put("no", p.getNo());
                product.put("name", p.getName());
                product.put("price", p.getPrice());
                product.put("stock", p.getStock());
                productList.put(product);
            }

            jsonResponse.put("status", "success");
            jsonResponse.put("data", productList);
            dos.writeUTF(jsonResponse.toString());
            dos.flush();
        }

        public void createProduct(JSONObject request) throws IOException {
            JSONObject jsonRequest = request.getJSONObject("data");
            JSONObject jsonResponse = new JSONObject();
            Product product = new Product();

            product.setNo(++pk);
            product.setName(jsonRequest.getString("name"));
            product.setPrice(jsonRequest.getInt("price"));
            product.setStock(jsonRequest.getInt("stock"));
            products.put(pk, product);

            jsonResponse.put("status", "success");
            jsonResponse.put("data", new JSONObject());
            dos.writeUTF(jsonResponse.toString());
            dos.flush();
        }

        public void updateProduct(JSONObject request) throws IOException {
            JSONObject jsonRequest = request.getJSONObject("data");
            JSONObject jsonResponse = new JSONObject();

            Product product = products.get(jsonRequest.getInt("no"));
            product.setName(jsonRequest.getString("name"));
            product.setPrice(jsonRequest.getInt("price"));
            product.setStock(jsonRequest.getInt("stock"));

            jsonResponse.put("status", "success");
            jsonResponse.put("jsonRequest", new JSONObject());
            dos.writeUTF(jsonResponse.toString());
            dos.flush();
        }

        public void deleteProduct(JSONObject request) throws IOException {
            JSONObject jsonRequest = request.getJSONObject("data");
            JSONObject jsonResponse = new JSONObject();
            products.remove(jsonRequest.getInt("no"));

            jsonResponse.put("status", "success");
            jsonResponse.put("data", new JSONObject());
            dos.writeUTF(jsonResponse.toString());
            dos.flush();
        }
    }
}

import org.json.JSONArray;
import org.json.JSONObject;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;

public class ProductClient {
    private Socket sc;
    private DataInputStream dis;
    private DataOutputStream dos;
    private Scanner scanner;

    public static void main(String[] args) {
        ProductClient productClient = new ProductClient();
        try {
            productClient.start();
        } catch (IOException ignored) {
        }
    }

    public void start() throws IOException {
        scanner = new Scanner(System.in);
        sc = new Socket("localhost", 50001);
        dis = new DataInputStream(sc.getInputStream());
        dos = new DataOutputStream(sc.getOutputStream());

        System.out.println("[클라이언트] 서버에 연결됨");
        getProductList();
    }

    public void exit() {
        try {
            sc.close();
            scanner.close();
        } catch (Exception ignored) {
        }
        System.out.println("[클라이언트] 종료됨");
    }

    public void getResponse() throws IOException {
        JSONObject jsonResponse = new JSONObject(dis.readUTF());
        if (jsonResponse.getString("status").equals("success")) {
            getProductList();
        }
    }

    public void getMenuNumber() throws IOException {
        System.out.println();
        System.out.println("----------------------------------------------------------");
        System.out.println("메뉴: 1.Create | 2.Update | 3.Delete | 4.Exit");
        System.out.print("선택: ");

        int menuNumber = Integer.parseInt(scanner.nextLine());
        System.out.println();

        switch (menuNumber) {
            case 1 -> createProduct();
            case 2 -> updateProduct();
            case 3 -> deleteProduct();
            default -> exit();
        }
    }

    public void getProductList() throws IOException {
        final int MENU_NUM = 1;
        JSONObject jsonRequest = new JSONObject();

        System.out.println();
        System.out.println("[상품 목록]");
        System.out.println("----------------------------------------------------------");
        System.out.println("no\t\tname\t\t\t\t\tprice\t\t\tstock");
        System.out.println("----------------------------------------------------------");

        jsonRequest.put("menu", MENU_NUM);
        jsonRequest.put("data", new JSONObject());

        dos.writeUTF(jsonRequest.toString());
        dos.flush();

        JSONObject jsonResponse = new JSONObject(dis.readUTF());

        if (jsonResponse.getString("status").equals("success")) {
            JSONArray jsonArray = jsonResponse.getJSONArray("data");

            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject product = jsonArray.getJSONObject(i);
                System.out.printf("%d\t\t%s\t\t\t\t\t\t%d\t\t\t\t%d\n",
                        product.getInt("no"),
                        product.getString("name"),
                        product.getInt("price"),
                        product.getInt("stock")
                );
            }
        }
        getMenuNumber();
    }

    public void createProduct() throws IOException {
        final int MENU_NUM = 1;
        Product product = new Product();
        JSONObject jsonProduct = new JSONObject();
        JSONObject jsonRequest = new JSONObject();

        System.out.println("[상품 생성]");

        System.out.print("상품 이름: ");
        product.setName(scanner.nextLine());

        System.out.print("상품 가격: ");
        product.setPrice(Integer.parseInt(scanner.nextLine()));

        System.out.print("상품 재고: ");
        product.setStock(Integer.parseInt(scanner.nextLine()));

        jsonProduct.put("name", product.getName());
        jsonProduct.put("price", product.getPrice());
        jsonProduct.put("stock", product.getStock());

        jsonRequest.put("menu", MENU_NUM);
        jsonRequest.put("data", jsonProduct);

        dos.writeUTF(jsonRequest.toString());
        dos.flush();
        getResponse();
    }

    public void updateProduct() throws IOException {
        final int MENU_NUM = 2;
        Product product = new Product();
        JSONObject jsonProduct = new JSONObject();
        JSONObject jsonRequest = new JSONObject();

        System.out.println("[상품 수정]");

        System.out.print("상품 번호: ");
        product.setNo(Integer.parseInt(scanner.nextLine()));

        System.out.print("이름 변경: ");
        product.setName(scanner.nextLine());

        System.out.print("가격 변경: ");
        product.setPrice(Integer.parseInt(scanner.nextLine()));

        System.out.print("재고 변경: ");
        product.setStock(Integer.parseInt(scanner.nextLine()));

        jsonProduct.put("no", product.getNo());
        jsonProduct.put("name", product.getName());
        jsonProduct.put("price", product.getPrice());
        jsonProduct.put("stock", product.getStock());

        jsonRequest.put("menu", MENU_NUM);
        jsonRequest.put("data", jsonProduct);

        dos.writeUTF(jsonRequest.toString());
        dos.flush();
        getResponse();
    }


    public void deleteProduct() throws IOException {
        final int MENU_NUM = 3;
        JSONObject jsonProduct = new JSONObject();
        JSONObject jsonRequest = new JSONObject();

        System.out.println("[상품 삭제]");

        System.out.print("상품 번호: ");
        int no = Integer.parseInt(scanner.nextLine());

        jsonProduct.put("no", no);

        jsonRequest.put("menu", MENU_NUM);
        jsonRequest.put("data", jsonProduct);

        dos.writeUTF(jsonRequest.toString());
        dos.flush();
        getResponse();
    }
}