將部件和其組裝過程分開，一步一步創建一個復雜的對象，并且對于客戶端而言不需要知道具體構建細節

// 復雜對象電腦
public class Computer {
    private Mouse mouse;
    private Keyboard keyboard;
    private CPU cpu;

    public Mouse getMouse() {
        return mouse;
    }

    public void setMouse(Mouse mouse) {
        this.mouse = mouse;
    }

    public Keyboard getKeyboard() {
        return keyboard;
    }

    public void setKeyboard(Keyboard keyboard) {
        this.keyboard = keyboard;
    }

    public CPU getCpu() {
        return cpu;
    }

    public void setCpu(CPU cpu) {
        this.cpu = cpu;
    }

    public void display() {
        System.out.println("cpu:" + this.cpu.getName() + " mouse:" + this.mouse.getName()
                + " keyboard:" + this.keyboard.getName());
    }
}

// 部件鼠標
public class Mouse {
    private String name;

    public Mouse(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

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

// 部件鍵盤
public class Keyboard {
    private String name;

    public Keyboard(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

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

// 部件處理器
public class CPU {
    private String name;

    public CPU(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

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

public interface ComputerBuilder {
    Mouse buildMouse();
    Keyboard buildKeyboard();
    CPU buildCPU();
}

public class DellComputerBuilder implements ComputerBuilder {
    @Override
    public Mouse buildMouse() {
        return new Mouse("dell brand mouse");
    }

    @Override
    public Keyboard buildKeyboard() {
        return new Keyboard("dell brand keyboard");
    }

    @Override
    public CPU buildCPU() {
        return new CPU("dell brand cpu");
    }
}


public interface ComputerDirector {
    Computer directComputer();
}

public class DellComputerDirector implements ComputerDirector {
    private ComputerBuilder builder;

    public DellComputerDirector(ComputerBuilder builder) {
        this.builder = builder;
    }

    @Override
    public Computer directComputer() {
        Mouse mouse = builder.buildMouse();
        Keyboard keyboard = builder.buildKeyboard();
        CPU cpu = builder.buildCPU();

        Computer computer = new Computer();
        computer.setMouse(mouse);
        computer.setKeyboard(keyboard);
        computer.setCpu(cpu);

        return computer;
    }
}

public class ComputerBuilderTest {
    public static void main(String[] args) {
        ComputerDirector director = new DellComputerDirector(new DellComputerBuilder());
        Computer computer = director.directComputer();
        computer.display();
    }
}