工廠方法模式定義了一個創建對象的接口，但由子類決定要實例化的類是哪一個。工廠方法讓類把實例化推遲到子類。
類圖
（圖片源於網絡）
代碼實現（Java）
產品類
// Pizza.java
public abstract class Pizza {
String name;
String dough;
String sauce;
ArrayList toppings = new ArrayList();
void prepare() {
System.out.println("Preparing " + name);
System.out.println("Tossing dough...");
System.out.println("Adding sauce...");
System.out.println("Adding toppings: ");
for (int i = 0; i < toppings.size(); i++) {
System.out.println(" " + toppings.get(i));
}
}
void bake() {
System.out.println("Bake for 25 minutes at 350");
}
void cut() {
System.out.println("Cutting the pizza into diagonal slices");
}
void box() {
System.out.println("Place pizza in official PizzaStore box");
}
public String getName() {
return name;
}
public String toString() {
StringBuffer display = new StringBuffer();
display.append("---- " + name + " ----\n");
display.append(dough + "\n");
display.append(sauce + "\n");
for (int i = 0; i < toppings.size(); i++) {
display.append((String )toppings.get(i) + "\n");
}
return display.toString();
}
}// NYStyleCheesePizza.java
public class NYStyleCheesePizza extends Pizza {
public NYStyleCheesePizza() {
name = "NY Style Sauce and Cheese Pizza";
dough = "Thin Crust Dough";
sauce = "Marinara Sauce";
toppings.add("Grated Reggiano Cheese");
}
}// NYStylePepperoniPizza.java
public class NYStylePepperoniPizza extends Pizza {
public NYStylePepperoniPizza() {
name = "NY Style Pepperoni Pizza";
dough = "Thin Crust Dough";
sauce = "Marinara Sauce";
toppings.add("Grated Reggiano Cheese");
toppings.add("Sliced Pepperoni");
toppings.add("Garlic");
toppings.add("Onion");
toppings.add("Mushrooms");
toppings.add("Red Pepper");
}
}// NYStyleClamPizza.java
public class NYStyleClamPizza extends Pizza {
public NYStyleClamPizza() {
name = "NY Style Clam Pizza";
dough = "Thin Crust Dough";
sauce = "Marinara Sauce";
toppings.add("Grated Reggiano Cheese");
toppings.add("Fresh Clams from Long Island Sound");
}
}// NYStyleVeggiePizza.java
public class NYStyleVeggiePizza extends Pizza {
public NYStyleVeggiePizza() {
name = "NY Style Veggie Pizza";
dough = "Thin Crust Dough";
sauce = "Marinara Sauce";
toppings.add("Grated Reggiano Cheese");
toppings.add("Garlic");
toppings.add("Onion");
toppings.add("Mushrooms");
toppings.add("Red Pepper");
}
}// ChicagoStyleCheesePizza.java
public class ChicagoStyleCheesePizza extends Pizza {
public ChicagoStyleCheesePizza() {
name = "Chicago Style Deep Dish Cheese Pizza";
dough = "Extra Thick Crust Dough";
sauce = "Plum Tomato Sauce";
toppings.add("Shredded Mozzarella Cheese");
}
void cut() {
System.out.println("Cutting the pizza into square slices");
}
}// ChicagoStylePepperoniPizza.java
public class ChicagoStylePepperoniPizza extends Pizza {
public ChicagoStylePepperoniPizza() {
name = "Chicago Style Pepperoni Pizza";
dough = "Extra Thick Crust Dough";
sauce = "Plum Tomato Sauce";
toppings.add("Shredded Mozzarella Cheese");
toppings.add("Black Olives");
toppings.add("Spinach");
toppings.add("Eggplant");
toppings.add("Sliced Pepperoni");
}
void cut() {
System.out.println("Cutting the pizza into square slices");
}
}// ChicagoStyleClamPizza.java
public class ChicagoStyleClamPizza extends Pizza {
public ChicagoStyleClamPizza() {
name = "Chicago Style Clam Pizza";
dough = "Extra Thick Crust Dough";
sauce = "Plum Tomato Sauce";
toppings.add("Shredded Mozzarella Cheese");
toppings.add("Frozen Clams from Chesapeake Bay");
}
void cut() {
System.out.println("Cutting the pizza into square slices");
}
}// ChicagoStyleVeggiePizza.java
public class ChicagoStyleVeggiePizza extends Pizza {
public ChicagoStyleVeggiePizza() {
name = "Chicago Deep Dish Veggie Pizza";
dough = "Extra Thick Crust Dough";
sauce = "Plum Tomato Sauce";
toppings.add("Shredded Mozzarella Cheese");
toppings.add("Black Olives");
toppings.add("Spinach");
toppings.add("Eggplant");
}
void cut() {
System.out.println("Cutting the pizza into square slices");
}
}創造者類
// PizzaStore.java
public abstract class PizzaStore {
abstract Pizza createPizza(String item);
public Pizza orderPizza(String type) {
Pizza pizza = createPizza(type);
System.out.println("--- Making a " + pizza.getName() + " ---");
pizza.prepare();
pizza.bake();
pizza.cut();
pizza.box();
return pizza;
}
}// NYPizzaStore.java
public class NYPizzaStore extends PizzaStore {
Pizza createPizza(String item) {
if (item.equals("cheese")) {
return new NYStyleCheesePizza();
} else if (item.equals("veggie")) {
return new NYStyleVeggiePizza();
} else if (item.equals("clam")) {
return new NYStyleClamPizza();
} else if (item.equals("pepperoni")) {
return new NYStylePepperoniPizza();
} else return null;
}
}// ChicagoPizzaStore.java
public class ChicagoPizzaStore extends PizzaStore {
Pizza createPizza(String item) {
if (item.equals("cheese")) {
return new ChicagoStyleCheesePizza();
} else if (item.equals("veggie")) {
return new ChicagoStyleVeggiePizza();
} else if (item.equals("clam")) {
return new ChicagoStyleClamPizza();
} else if (item.equals("pepperoni")) {
return new ChicagoStylePepperoniPizza();
} else return null;
}
}測試代碼
// PizzaTestDrive.java
public class PizzaTestDrive {
public static void main(String[] args) {
PizzaStore nyStore = new NYPizzaStore();
PizzaStore chicagoStore = new ChicagoPizzaStore();
Pizza pizza = nyStore.orderPizza("cheese");
System.out.println("Ethan ordered a " + pizza.getName() + "\n");
pizza = chicagoStore.orderPizza("cheese");
System.out.println("Joel ordered a " + pizza.getName() + "\n");
pizza = nyStore.orderPizza("clam");
System.out.println("Ethan ordered a " + pizza.getName() + "\n");
pizza = chicagoStore.orderPizza("clam");
System.out.println("Joel ordered a " + pizza.getName() + "\n");
pizza = nyStore.orderPizza("pepperoni");
System.out.println("Ethan ordered a " + pizza.getName() + "\n");
pizza = chicagoStore.orderPizza("pepperoni");
System.out.println("Joel ordered a " + pizza.getName() + "\n");
pizza = nyStore.orderPizza("veggie");
System.out.println("Ethan ordered a " + pizza.getName() + "\n");
pizza = chicagoStore.orderPizza("veggie");
System.out.println("Joel ordered a " + pizza.getName() + "\n");
}
}運行效果
--- Making a NY Style Sauce and Cheese Pizza --- Preparing NY Style Sauce and Cheese Pizza Tossing dough... Adding sauce... Adding toppings: Grated Reggiano Cheese Bake for 25 minutes at 350 Cutting the pizza into diagonal slices Place pizza in official PizzaStore box Ethan ordered a NY Style Sauce and Cheese Pizza --- Making a Chicago Style Deep Dish Cheese Pizza --- Preparing Chicago Style Deep Dish Cheese Pizza Tossing dough... Adding sauce... Adding toppings: Shredded Mozzarella Cheese Bake for 25 minutes at 350 Cutting the pizza into square slices Place pizza in official PizzaStore box Joel ordered a Chicago Style Deep Dish Cheese Pizza --- Making a NY Style Clam Pizza --- Preparing NY Style Clam Pizza Tossing dough... Adding sauce... Adding toppings: Grated Reggiano Cheese Fresh Clams from Long Island Sound Bake for 25 minutes at 350 Cutting the pizza into diagonal slices Place pizza in official PizzaStore box Ethan ordered a NY Style Clam Pizza --- Making a Chicago Style Clam Pizza --- Preparing Chicago Style Clam Pizza Tossing dough... Adding sauce... Adding toppings: Shredded Mozzarella Cheese Frozen Clams from Chesapeake Bay Bake for 25 minutes at 350 Cutting the pizza into square slices Place pizza in official PizzaStore box Joel ordered a Chicago Style Clam Pizza --- Making a NY Style Pepperoni Pizza --- Preparing NY Style Pepperoni Pizza Tossing dough... Adding sauce... Adding toppings: Grated Reggiano Cheese Sliced Pepperoni Garlic Onion Mushrooms Red Pepper Bake for 25 minutes at 350 Cutting the pizza into diagonal slices Place pizza in official PizzaStore box Ethan ordered a NY Style Pepperoni Pizza --- Making a Chicago Style Pepperoni Pizza --- Preparing Chicago Style Pepperoni Pizza Tossing dough... Adding sauce... Adding toppings: Shredded Mozzarella Cheese Black Olives Spinach Eggplant Sliced Pepperoni Bake for 25 minutes at 350 Cutting the pizza into square slices Place pizza in official PizzaStore box Joel ordered a Chicago Style Pepperoni Pizza --- Making a NY Style Veggie Pizza --- Preparing NY Style Veggie Pizza Tossing dough... Adding sauce... Adding toppings: Grated Reggiano Cheese Garlic Onion Mushrooms Red Pepper Bake for 25 minutes at 350 Cutting the pizza into diagonal slices Place pizza in official PizzaStore box Ethan ordered a NY Style Veggie Pizza --- Making a Chicago Deep Dish Veggie Pizza --- Preparing Chicago Deep Dish Veggie Pizza Tossing dough... Adding sauce... Adding toppings: Shredded Mozzarella Cheese Black Olives Spinach Eggplant Bake for 25 minutes at 350 Cutting the pizza into square slices Place pizza in official PizzaStore box Joel ordered a Chicago Deep Dish Veggie Pizza |