用lambda简化工厂设计模式

最新推荐文章于 2021-02-26 10:52:55 发布

翻译最新推荐文章于 2021-02-26 10:52:55 发布 · 232 阅读

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#lambda #设计模式

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本文探讨了传统工厂设计模式的实现方式，并引入了Lambda表达式来简化代码。通过具体示例，展示了如何使用Map和Supplier接口创建一个冰淇淋工厂，以及如何在构造器需要参数的情况下重新定义功能接口。

传统工厂设计模式实现：

import java.util.HashMap;
import java.util.Map;
import java.util.function.Supplier;

public class FactoryPattern {

    public final static Map<String, Supplier<Icecream>> iceCreamStation = new HashMap<>();
    static {
        iceCreamStation.put("choclet", ChocletIceCream::new);
        iceCreamStation.put("strawberry", StrawberryIceCream::new);
    }

    public static void main(String[] args) {
        Supplier<Icecream> supplier = iceCreamStation.get("choclet");
        if(supplier != null){
            Icecream chocletIceCream = supplier.get();
            System.out.println(chocletIceCream);
        }
    }
    
    private static class ChocletIceCream implements Icecream{ }

    private static class StrawberryIceCream implements Icecream{}
}

interface Icecream{}

用lambda简化后的工厂模式：

import java.util.HashMap;
import java.util.Map;
import java.util.function.Supplier;

public class FactoryPattern {

    public final static Map<String, Supplier<Icecream>> iceCreamStation = new HashMap<>();
    static {
        iceCreamStation.put("choclet", ChocletIceCream::new);
        iceCreamStation.put("strawberry", StrawberryIceCream::new);
    }

    public static void main(String[] args) {
        Supplier<Icecream> supplier = iceCreamStation.get("choclet");
        if(supplier != null){
            Icecream chocletIceCream = supplier.get();
            System.out.println(chocletIceCream);
        }
    }
    
    private static class ChocletIceCream implements Icecream{ }

    private static class StrawberryIceCream implements Icecream{}
}

interface Icecream{}

如果构造器需要参数，看情况重新定义功能接口：


interface TriFunction<T, Y, U, R>{
    
    R apply(T t, Y y, U u);
}
    public final static Map<String, TriFunction<String, Integer, Integer, Icecream>> threeParams = new HashMap<>();