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Завдання: Implement a simple point of sale.
Assume you have:
– one input device: bar codes scanner
– two output devices: LCD display and printer
Implement:
– single product sale: products bar code is scanned and:
– if the product is found in products database than it's name and price is printed on LCD
– if the product is not found than error message 'Product not found' is printed on LCD
– if the code scanned is empty than error message 'Invalid bar-code' is printed on LCD
– when 'exit' is input than receipt is printed on printer containing a list of all previously scanned items names and prices as well as total sum to be paid for all items; the total sum is also printed on LCD display
Rules:
– use only SDK classes and your favorite test libraries
– mock/stub the database and IO devices
– concentrate on proper design and clean code, rather than supplying fully functioning application
Реалізація:
Клас SalePoint
public class SalePoint {
private InputDevice codesScanner = new CodesScanner();
private DBWorker dbWorker = null;
private OutputDevice lcdDisplay = new LCDDisplay();
private OutputDevice printer = new Printer();
private List<Product> list = new ArrayList<Product>();
public SalePoint(){
try {
dbWorker = new DBWorker();
} catch (SQLException e) {
e.printStackTrace();
}
}
public void setDefaultBarCodes(){
codesScanner.write("exit");
codesScanner.write("");
codesScanner.write("0000000001");
codesScanner.write("0000000002");
}
public void run() {
try {
Product product = null;
while(codesScanner.hasNext()) {
String barCode = codesScanner.readLine();
switch (barCode) {
case "":
lcdDisplay.printError("Product not found");
break;
case "exit":
printer.println("Printer: ");
printProducts();
return;
default:
product = dbWorker.findProduct(barCode);
if (product == null) {
lcdDisplay.printError("Invalid bar-code");
}
lcdDisplay.print(product);
list.add(product);
}
}
} catch (EmptyStackException e) {
e.printStackTrace();
}
}
private void printProducts() {
double summ = 0.0;
for (Product product :
list) {
summ += product.getPrice();
}
((Printer)printer).printProductsAndTotalPrice(list, summ);
}
}
Class InputDevice
public class InputDevice {
private Stack<String> buffer = new Stack<>();
public void write(String message){
buffer.push(message);
}
public String readLine(){
if(buffer.isEmpty())
return null;
return buffer.pop();
}
public void clear(){
buffer.clear();
}
public boolean hasNext(){
return !buffer.isEmpty();
}
}
Class CodesScaner
public class CodesScanner extends InputDevice{
public CodesScanner() {
super();
}
// Не знаю який метод додати.
}
Class OutputDevice
public class OutputDevice {
void println(String message){
System.out.println(message);
}
void print(String message){
System.out.print(message);
}
void printError(String message){
System.out.println("Error: " + message);
}
void print(Product product){
System.out.println(product);
}
}
Class Printer
public class Printer extends OutputDevice {
public Printer() {
super();
}
public void printProducts(List<Product> productList){
System.out.println("List of products:");
for (Product product:
productList) {
System.out.println(product.getName() + "\t\t\t" + product.getPrice());
}
}
public void printProductsAndTotalPrice(List<Product> productList, double totalPrice){
System.out.println("List of products:\nName\t\t\tPrice");
for (Product product:
productList) {
System.out.println(product.getName() + "\t\t\t" + product.getPrice());
}
System.out.println("Total:\t\t\t" + totalPrice);
}
}
Class LCDDisplay
public class LCDDisplay extends OutputDevice {
public LCDDisplay() {
}
public void print(Product product){
System.out.println(product.getName() + "\t\t" + product.getPrice());
}
}
Class DBWorker
public class DBWorker {
private static String URL = "jdbc:mysql://localhost:3306/mydbtest";
private static String USERNAME = "root";
private static String PASSWORD = "root";
private static String SELECT = "SELECT product_name, price, bar_code FROM products WHERE bar_code = ?;";
private Connection connection;
public DBWorker() throws SQLException {
Driver driver = new FabricMySQLDriver();
DriverManager.registerDriver(driver);
connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
}
public Product findProduct(String barCode) {
Product product = null;
PreparedStatement preparedStatement = null;
try {
preparedStatement = connection.prepareStatement(SELECT);
preparedStatement.setString(1, barCode);
ResultSet resultSet = preparedStatement.executeQuery();
if(resultSet.next())
product = new Product(resultSet.getString("product_name"), resultSet.getInt("price"), resultSet.getString("bar_code"));
} catch (SQLException e) {
e.printStackTrace();
}
return product;
}
}
main
public class Main {
public static void main(String[] args) {
SalePoint salePoint = new SalePoint();
salePoint.setDefaultBarCodes();
salePoint.run();
}
}
Як на ваш погляд моя реалізація?
І не підскажите як зробити тести? Juint i Mockito
Тільки один зробив але не розумію навіщо він - бесполезний.
public class DBTest {
private static final Product PRODUCT = new Product("beer", 2.3, "0000000001");
private static final String BAR_CODE = "0000000001";
@Mock
SalePoint salePoint;
@Test
public void testFindProduct(){
DBWorker dbWorker = mock(DBWorker.class);
when(dbWorker.findProduct(BAR_CODE)).thenReturn(new Product("beer", 2.3, "0000000001"));
Product product = dbWorker.findProduct(BAR_CODE);
Assert.assertEquals(product, PRODUCT);
}
}
