用idea设计一个系统，要使用三种设计模式和一种体系结构的代码

好的，以下是使用三种设计模式和一种体系结构的代码示例：

设计模式：

1. 工厂模式（Factory Pattern）

public interface Product {
    void use();
}

public class ProductA implements Product {
    @Override
    public void use() {
        System.out.println("使用产品A");
    }
}

public class ProductB implements Product {
    @Override
    public void use() {
        System.out.println("使用产品B");
    }
}

public class Factory {
    public static Product createProduct(String type) {
        if (type.equals("A")) {
            return new ProductA();
        } else if (type.equals("B")) {
            return new ProductB();
        } else {
            return null;
        }
    }
}

public class Test {
    public static void main(String[] args) {
        Product product = Factory.createProduct("A");
        product.use();
    }
}

2. 观察者模式（Observer Pattern）

public interface Observer {
    void update();
}

public class ConcreteObserverA implements Observer {
    @Override
    public void update() {
        System.out.println("观察者A收到通知");
    }
}

public class ConcreteObserverB implements Observer {
    @Override
    public void update() {
        System.out.println("观察者B收到通知");
    }
}

public interface Subject {
    void addObserver(Observer observer);
    void removeObserver(Observer observer);
    void notifyObservers();
}

public class ConcreteSubject implements Subject {
    private List<Observer> observers = new ArrayList<>();

    @Override
    public void addObserver(Observer observer) {
        observers.add(observer);
    }

    @Override
    public void removeObserver(Observer observer) {
        observers.remove(observer);
    }

    @Override
    public void notifyObservers() {
        for (Observer observer : observers) {
            observer.update();
        }
    }
}

public class Test {
    public static void main(String[] args) {
        Observer observerA = new ConcreteObserverA();
        Observer observerB = new ConcreteObserverB();

        Subject subject = new ConcreteSubject();
        subject.addObserver(observerA);
        subject.addObserver(observerB);
        subject.notifyObservers();
    }
}

3. 命令模式（Command Pattern）

public interface Command {
    void execute();
}

public class ConcreteCommandA implements Command {
    private Receiver receiver;

    public ConcreteCommandA(Receiver receiver) {
        this.receiver = receiver;
    }

    @Override
    public void execute() {
        receiver.actionA();
    }
}

public class ConcreteCommandB implements Command {
    private Receiver receiver;

    public ConcreteCommandB(Receiver receiver) {
        this.receiver = receiver;
    }

    @Override
    public void execute() {
        receiver.actionB();
    }
}

public class Invoker {
    private Command command;

    public void setCommand(Command command) {
        this.command = command;
    }

    public void executeCommand() {
        command.execute();
    }
}

public class Receiver {
    public void actionA() {
        System.out.println("执行操作A");
    }

    public void actionB() {
        System.out.println("执行操作B");
    }
}

public class Test {
    public static void main(String[] args) {
        Receiver receiver = new Receiver();
        Command commandA = new ConcreteCommandA(receiver);
        Command commandB = new ConcreteCommandB(receiver);

        Invoker invoker = new Invoker();
        invoker.setCommand(commandA);
        invoker.executeCommand();

        invoker.setCommand(commandB);
        invoker.executeCommand();
    }
}

体系结构：

使用MVC（Model-View-Controller）体系结构：

// Model
public class UserModel {
    private String name;
    private int age;

    public UserModel(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

// View
public class UserView {
    public void printUserDetails(String name, int age) {
        System.out.println("User:");
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
    }
}

// Controller
public class UserController {
    private UserModel model;
    private UserView view;

    public UserController(UserModel model, UserView view) {
        this.model = model;
        this.view = view;
    }

    public void setUserName(String name) {
        model.name = name;
    }

    public void setUserAge(int age) {
        model.age = age;
    }

    public String getUserName() {
        return model.getName();
    }

    public int getUserAge() {
        return model.getAge();
    }

    public void updateUserView() {
        view.printUserDetails(model.getName(), model.getAge());
    }
}

// Test
public class Test {
    public static void main(String[] args) {
        UserModel model = new UserModel("Tom", 20);
        UserView view = new UserView();
        UserController controller = new UserController(model, view);

        controller.updateUserView();

        controller.setUserName("Jerry");
        controller.setUserAge(30);
        controller.updateUserView();
    }
}

这个代码示例使用了工厂模式、观察者模式、命令模式和MVC体系结构。这些设计模式和体系结构可以使系统具有更好的可维护性、可扩展性和灵活性。