Java设计模式泛型化之建造者模式

来源：互联网发布：java equals的用法编辑：程序博客网时间：2024/06/08 04:27

建造者模式的理解是这样的：

一件事情可以分为有限的几个步骤，或者几个部分。规定了各个步骤或部分的建造方法。然后得到一个具体的事物或者完成该事件。

其结构是这样的：

一个抽象的建造者接口几个具体的建造者实现类一个指挥者一个调用者

具体先看看代码：

抽象建造者接口

public interface Builder {public void buildPartA();public void buildPartB();public void returnResult();}

具体建造者实现类

public class BuilderA implements Builder {@Overridepublic void buildPartA() {System.out.println("Builder A builds part A.");}@Overridepublic void buildPartB() {System.out.println("Builder A builds part B.");}@Overridepublic void returnResult() {System.out.println("Builder A returns part A and part B.");}}

public class BuilderB implements Builder {@Overridepublic void buildPartA() {System.out.println("Builder B builds part A.");}@Overridepublic void buildPartB() {System.out.println("Builder B builds part B.");}@Overridepublic void returnResult() {System.out.println("Builder B returns part A and part B.");}}

指挥者

public class Director {private Builder prod;public Director(Builder prod) {this.prod = prod;}public void build() {prod.returnResult();prod.returnResult();}}

调用者

public class BuilderCaller {public static void main(String[] args) {Builder builderA = new BuilderA();Director directorA = new Director(builderA);directorA.build();Builder builderB = new BuilderB();Director directorB = new Director(builderB);directorB.build();}}

那么该如何泛型化呢？

不难看出，关键就在于Director类。以下是泛型化代码：

@SuppressWarnings("all")public class Director<T extends Builder> {private T t;public Director(Class<? extends Builder> c) {try {t = (T) Class.forName(c.getName()).newInstance();} catch (Exception e) {e.printStackTrace();}}public void build() {t.returnResult();t.returnResult();}}

调用者

public class BuilderCaller {public static void main(String[] args) {Director<BuilderA> dA = new Director<BuilderA>(BuilderA.class);dA.build();Director<BuilderB> dB = new Director<BuilderB>(BuilderB.class);dB.build();}}

当然，你也可以用抽象类来设计。

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