Java中的建造者模式

模式属于创建型模式，它提供了一种创建对象的最佳方式。使用多个简单的对象一步一步构建成一个复杂的对象。一个Builder类会一步一步构造最终的对象。该Builder类是独立于其他对象的。

指挥者模式

//产品
public class Product {
    private String one;
    private String two;
    private String three;

    public String getOne() {
        return one;
    }

    public void setOne(String one) {
        this.one = one;
    }

    public String getTwo() {
        return two;
    }

    public void setTwo(String two) {
        this.two = two;
    }

    public String getThree() {
        return three;
    }

    public void setThree(String three) {
        this.three = three;
    }

    @Override
    public String toString() {
        return "Product{" +
                "one='" + one + ''' +
                ", two='" + two + ''' +
                ", three='" + three + ''' +
                '}';
    }
}

//抽象的建造者
public abstract class Builder {
    abstract void one();//第一步工序

    abstract void two();//第二步工序

    abstract void three();//第三步工序

    abstract Product getProduct();//完工，得到产品
}

//具体的建造者：工人
public class Worker extends Builder {
    private Product product;

    public Worker() {
        product = new Product();
    }

    @Override
    void one() {
        product.setOne("第一步工序");
        System.out.println("第一步工序");
    }

    @Override
    void two() {
        product.setTwo("第二步工序");
        System.out.println("第二步工序");
    }

    @Override
    void three() {
        product.setThree("第三步工序");
        System.out.println("第三步工序");
    }

    @Override
    Product getProduct() {
        return product;
    }
}

//指挥者
public class Director {
    //指挥工人生成产品
    public Product build(Builder builder){
        builder.one();
        builder.two();
        builder.three();

        return builder.getProduct();
    }
}

public class Test {
    public static void main(String[] args) {
        //指挥者
        Director director = new Director();
        //指挥工人生产产品
        Product product = director.build(new Worker());
        System.out.println(product);

        
    }
}

第一步工序
第二步工序
第三步工序
Product{one='第一步工序', two='第二步工序', three='第三步工序'}

内部类模式

//产品
public class Product {
    private String one = "第一步工序";
    private String two = "第二步工序";
    private String three = "第三步工序";

    public String getOne() {
        return one;
    }

    public void setOne(String one) {
        this.one = one;
    }

    public String getTwo() {
        return two;
    }

    public void setTwo(String two) {
        this.two = two;
    }

    public String getThree() {
        return three;
    }

    public void setThree(String three) {
        this.three = three;
    }

    @Override
    public String toString() {
        return "Product{" +
                "one='" + one + ''' +
                ", two='" + two + ''' +
                ", three='" + three + ''' +
                '}';
    }
}

//抽象的建造者
public abstract class Builder {
    abstract Builder one(String mes);//第一步工序

    abstract Builder two(String mes);//第二步工序

    abstract Builder three(String mes);//第三步工序

    abstract Product getProduct();//完工，得到产品
}

//具体的建造者：工人
public class Worker extends Builder {
    private Product product;

    public Worker() {
        product = new Product();
    }

    @Override
    Builder one(String mes) {
        product.setOne(mes);
        return this;
    }

    @Override
    Builder two(String mes) {
        product.setTwo(mes);
        return this;
    }

    @Override
    Builder three(String mes) {
        product.setThree(mes);
        return this;
    }

    @Override
    Product getProduct() {
        return product;
    }
}

public class Test {
    public static void main(String[] args) {
        //工人
        Worker worker = new Worker();
        //生产产品
        Product product = worker.getProduct();
        System.out.println(product.toString());
        

        //链式编程
        product = worker.one("第一步额外工序").three("提前第三步工序").getProduct();
        System.out.println(product);
        
    }
}

Product{one='第一步工序', two='第二步工序', three='第三步工序'}
Product{one='第一步额外工序', two='第二步工序', three='提前第三步工序'}