建造者模式

概要

• 建造者模式属于创造型
• Builder模式可以将一个类的构建和表示进行分离

  将一个复杂的对象的构建与它的表示分离，使
  得同样的构建过程可以创建不同的表示。创建者模式隐藏了复杂对象的创建过程，它把复杂对象的创建过程加以抽象，通过子类继承或者重载的方式，动态的创建具有复合属性的对象。

经典模式

@Data
class Computer {
    private String cup;
    private String gpu;
    private String disk;
    private String ram;
}
@Data
abstract class ComputerBuilder {
    abstract void setCup();
    abstract void setGpu();
    abstract void setDisk();
    abstract void setRam();
    abstract Computer getComputer();
}
class HigherComputerBuilder extends ComputerBuilder {
    private Computer computer;
    public HigherComputerBuilder() {
        this.computer = new Computer();
    }
    @Override
    void setCup() {
        computer.setCup("8G");
    }
    @Override
    void setGpu() {
        computer.setGpu("4G");
    }
    @Override
    void setDisk() {
        computer.setDisk("1T");
    }
    @Override
    void setRam() {
        computer.setRam("16G");
    }
    @Override
    Computer getComputer() {
        return computer;
    }
}
class TowerComputerBuilder extends ComputerBuilder {
    private Computer computer;
    public TowerComputerBuilder() {
        this.computer = new Computer();
    }
    @Override
    void setCup() {
        computer.setCup("4G");
    }
    @Override
    void setGpu() {
        computer.setGpu("2G");
    }
    @Override
    void setDisk() {
        computer.setDisk("500G");
    }
    @Override
    void setRam() {
        computer.setRam("8G");
    }
    @Override
    Computer getComputer() {
        return computer;
    }
}
class Director {
    private ComputerBuilder computerBuilder;
    public Director(ComputerBuilder computerBuilder) {
        this.computerBuilder = computerBuilder;
    }
    public Computer createComputerBuilder() {
        computerBuilder.setCup();
        computerBuilder.setDisk();
        computerBuilder.setGpu();
        computerBuilder.setRam();
        return computerBuilder.getComputer();
    }
}
public class Main {
    public static void main(String[] args) {
        Computer computer = new Director(new HigherComputerBuilder()).createComputerBuilder();
        System.out.println("高配：" + computer);
        computer = new Director(new TowerComputerBuilder()).createComputerBuilder();
        System.out.println("低配：" + computer);
    }
}

变种模式

@Data
class Person {
    private String name;
    private String gender;
    private int age;
    private double money;
    private String house;
}
class PersonBuilder {
    private String name;
    private String gender;
    private int age;
    private double money;
    private String house;
    public PersonBuilder(String name, String gender) {
        this.name = name;
        this.gender = gender;
    }
    public PersonBuilder age(int age) {
        this.age = age;
        return this;
    }
    public PersonBuilder money(double money) {
        this.money = money;
        return this;
    }
    public PersonBuilder house(String house) {
        this.house = house;
        return this;
    }
    public Person build() {
        Person person = new Person();
        person.setName(name);
        person.setAge(age);
        person.setGender(gender);
        person.setMoney(money);
        person.setHouse(house);
        return person;
    }
}
public class VarietyBuilder {
    public static void main(String[] args) {
        System.out.println(new PersonBuilder("小明", "man")
                .age(11).house("big")
                .money(1111111111).build());
    }
}