1. 建造者（Builder）模式

创建的东西细节复杂，还必须暴露给使用者。屏蔽过程而不屏蔽细节

产品角色（Product）：Phone

/**
 * 只暴露get方法 不暴露set方法
 */
public class Phone {
    protected String cpu;
    protected String mem;
    protected String disk;
    protected String cam;
    public String getCpu() {
        return cpu;
    }
    public String getMem() {
        return mem;
    }
    public String getDisk() {
        return disk;
    }
    public String getCam() {
        return cam;
    }
    @Override
    public String toString() {
        return "Phone{" +
                "cpu='" + cpu + '\'' +
                ", mem='" + mem + '\'' +
                ", disk='" + disk + '\'' +
                ", cam='" + cam + '\'' +
                '}';
    }
}

抽象建造者（Builder）：AbstracPhoneBuilder

public abstract class AbstractBuilder {
    Phone phone;
    abstract void customCpu(String cpu);
    abstract void customMem(String mem);
    abstract void customDisk(String disk);
    abstract void customCam(String cam);
    Phone getProduct() {
        return phone;
    }
}

具体建造者(Concrete Builder）：PhoneBuilder

public class XiaomiBuilder extends AbstractBuilder {
    public XiaomiBuilder() {
        phone = new Phone();
    }
    @Override
    void customCpu(String cpu) {
        phone.cpu = cpu;
    }
    @Override
    void customMem(String mem) {
        phone.mem = mem;
    }
    @Override
    void customDisk(String disk) {
        phone.disk = disk;
    }
    @Override
    void customCam(String cam) {
        phone.cam = cam;
    }
}

测试方法：

    public static void main(String[] args) {
        AbstractBuilder builder = new XiaomiBuilder();
        builder.customCpu("骁龙888");
        builder.customCam("一亿");
        builder.customDisk("512G");
        builder.customMem("12G");
    }

在建造者模式中常用的链式我们也可以实现，只需将设置属性方法返回自身即可。

抽象建造者：

public abstract class AbstractBuilder2 {
    Phone phone;
    abstract AbstractBuilder2 customCpu(String cpu);
    abstract AbstractBuilder2 customMem(String mem);
    abstract AbstractBuilder2 customDisk(String disk);
    abstract AbstractBuilder2 customCam(String cam);
    Phone getProduct() {
        return phone;
    }
}

具体建造者：

public class XiaomiBuilder2 extends AbstractBuilder2 {
    public XiaomiBuilder2() {
        phone = new Phone();
    }
    @Override
    AbstractBuilder2 customCpu(String cpu) {
        phone.cpu = cpu;
        return this;
    }
    @Override
    AbstractBuilder2 customMem(String mem) {
        phone.mem = mem;
        return this;
    }
    @Override
    AbstractBuilder2 customDisk(String disk) {
        phone.disk = disk;
        return this;
    }
    @Override
    AbstractBuilder2 customCam(String cam) {
        phone.cam = cam;
        return this;
    }
}

测试方法：

    public static void main(String[] args) {
        //链式调用
        AbstractBuilder2 builder2 = new XiaomiBuilder2();
        Phone phone2 = builder2.customCpu("天玑9000").customCam("6400万").customMem("12G")
                .customDisk("512G").getProduct();
        System.out.println(phone2);
    }

2. 应用场景

• StringBuilder：append(); 给谁append呢？
• Swagger-ApiBuilder：
• 快速实现。Lombok-Builder模式

• 编写代码的时候使用到了设计模式。类+模式

  • xxxFactory
  • xxxTemplate
  • xxxBuilder
  • xxxFacede