Java设计模式之构建者模式

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已于 2022-10-21 14:36:33 修改

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文章标签： java 设计模式

于 2022-10-19 16:21:27 首次发布

本文链接：https://blog.youkuaiyun.com/jiuyuemo1/article/details/127410161

版权

本文介绍了Java中两种实现构建者模式的方法：1) 使用Lombok的构造器，通过BuilderHolder类实现链式构建；2) 自定义构造器，利用 Supplier 和 Consumer 接口进行对象构建。这两种方式都提供了灵活的构建过程，方便创建复杂对象。

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设计模式之构建者模式

介绍两种写法

1.lombok构造器

public class Builder {

    private int age;
    private String name;

    private Builder(){}

    public static Builder.BuilderHolder builder(){
        return new Builder.BuilderHolder();
    }

    public static class BuilderHolder{
        private int age;
        private String name;

        public BuilderHolder age(int age){
            this.age = age;
            return this;
        }
        public BuilderHolder name(String name){
            this.name = name;
            return this;
        }

        public Builder build(){
            Builder builder = new Builder();
            builder.age = this.age;
            builder.name = this.name;
            return builder;
        }

    }

}

测试类

public class BuilderTest {

    public static void main(String[] args) {
        Builder builder = Builder.builder()
                .age(1)
                .name("张三")
                .build();
    }

}

2.自定义构造器

public class Builder2<T> {

    private final Supplier<T> instance;

    private final  List<Consumer<T>> modifiers = new ArrayList<>();

    public Builder2(Supplier<T> instance) {
        this.instance = instance;
    }

    public static <T> Builder2<T> of(Supplier<T> instance) {
        return new Builder2<>(instance);
    }

    public <P> Builder2<T> with(BiConsumer<T, P> consumer, P p) {
        Consumer<T> c = instance -> consumer.accept(instance, p);
        modifiers.add(c);
        return this;
    }

    public T build() {
        T value = instance.get();
        modifiers.forEach(modifiers -> modifiers.accept(value));
        modifiers.clear();
        return value;
    }
}

测试类

public class Test1 {

    public static void main(String[] args) {
        MsoShareOrder msoShareOrder = Builder2.of(MsoShareOrder::new)
                .with(MsoShareOrder::setAgentName, "111")
                .with(MsoShareOrder::setAgentNo, "666")
                .with(MsoShareOrder::setMerNo, "A111")
                .build();
    }

}