设计模式――工厂方法模式（Factory Method Pattern）

// 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");
}
}

// 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;
}
}

// 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");
}
}