JAVA设计模式- 建造者模式

class Product
{

    private final String part1;
    private final String part2;
    private final String part3;
    private final String part4;
    //  .....
    
  public Product(String part1, String part2, String part3, String part4) {
        this.part1 = part1;
        this.part2 = part2;
        this.part3 = part3;
        this.part4 = part4;
    }

    public String getPart1() {
        return part1;
    }

    public String getPart2() {
        return part2;
    }

    public String getPart3() {
        return part3;
    }

    public String getPart4() {
        return part4;
    }

    @Override
    public String toString() {
        return "Product{" +
                "part1='" + part1 + ''' +
                ", part2='" + part2 + ''' +
                ", part3='" + part3 + ''' +
                ", part4='" + part4 + ''' +
                '}';
    }

    static class Builder
    {
        private String part1;
        private String part2;
        private String part3;
        private String part4;

        public Builder builderPart1(String part1) {
            this.part1 = part1;
            return this;
        }

        public Builder builderPart2(String part2) {
            this.part2 = part2;
            return this;
        }

        public Builder builderPart3(String part3) {
            this.part3 = part3;
            return this;
        }

        public Builder builderPart4(String part4) {
            this.part4 = part4;
            return this;
        }

        Product build() {
            return new Product(part1, part2, part3, part4);
        }
    }
    
    
    //使用方式
    
public class BuilderTest2
{
    public static void main(String[] args) {

        Product.Builder builder = new Product.Builder().builderPart1("part1").builderPart2("part2");

        if (true) {
            builder.builderPart3("part3");
        }

        Product.Builder part4 = builder.builderPart4("part4");
        Product product = part4.build();
        System.out.println(product);
    }
}

public class Product {
    private String partA;
    private String partB;
    private String partC;

    public void setPartA(String partA) {
        this.partA = partA;
    }

    public void setPartB(String partB) {
        this.partB = partB;
    }

    public void setPartC(String partC) {
        this.partC = partC;
    }

    @Override
    public String toString() {
        return "Product{" +
                "partA='" + partA + ''' +
                ", partB='" + partB + ''' +
                ", partC='" + partC + ''' +
                '}';
    }
}

abstract class Builder {
    //创建产品对象
    protected Product product = new Product();

    public abstract void buildPartA();

    public abstract void buildPartB();

    public abstract void buildPartC();

    //返回产品对象
    public Product build() {
        return product;
    }
}

public class ConcreteBuilder extends Builder {
    public void buildPartA() {
        product.setPartA("设置 PartA");
    }

    public void buildPartB() {
        product.setPartB("设置 PartB");
    }

    public void buildPartC() {
        product.setPartC("设置 PartC");
    }
}

class Director {
    private Builder builder;

    public Director(Builder builder) {
        this.builder = builder;
    }

    //产品构建与组装方法
    public Product construct() {
        builder.buildPartA();
        builder.buildPartB();
        builder.buildPartC();
        return builder.build();
    }
}

public class Client
{
    public static void main(String[] args) {
        Builder builder = new ConcreteBuilder();
        Director director = new Director(builder);
        Product product = director.construct();
        System.out.println(product.toString());
    }
}