建造者模式

将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示。

结构图如下：

 

Builder:是为创建Product对象各个部件的抽象接口；

Product:具体产品角色;

Director：指挥者,构建一个使用Builder接口的对象;

public class Product {

    List<String> parts = new ArrayList<>();

    public void add(String part){
        parts.add(part);
    }

    public void show(){
        System.out.println("\n产品 创建 ----");
        parts.forEach(System.out::println);
    }

}


public abstract class Builder {

    public abstract  void builderPartA();

    public abstract  void  builderPartB();

    public abstract Product getResult();
}

public class ConcreteBuilder1 extends  Builder {

    private Product product = new Product();

    @Override
    public void builderPartA(){
        product.add("部件A");
    }

    @Override
    public void  builderPartB(){
        product.add("部件B");
    }

    @Override
    public Product getResult(){
        return product;
    }
    
}


public class ConcreteBuilder2 extends Builder {

    private Product product = new Product();

    @Override
    public void builderPartA(){
        product.add("部件X");
    }

    @Override
    public void  builderPartB(){
        product.add("部件Y");
    }

    @Override
    public Product getResult(){
        return product;
    }

}

public class Director {

    public void construct (Builder builder){
        builder.builderPartA();
        builder.builderPartB();
    }

}

public class builderMain {

    public static  void main(String[] args){

        Director director = new Director();
        Builder b1 = new ConcreteBuilder1();
        Builder b2 = new ConcreteBuilder2();
        director.construct(b1);
        b1.getResult().show();

        director.construct(b2);
        b2.getResult().show();

    }

}

结果如下:

/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/bin/java "-javaagent:/Applications/IntelliJ IDEA CE.app/Contents/lib/idea_rt.jar=49865:/Applications/IntelliJ IDEA CE.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home/lib/tools.jar:/Users/liuxuwei/IdeaProjects/dahuadesignmodel/out/production/dahuadesignmodel buildermodel8.builderMain

产品 创建 ----
部件A
部件B

产品 创建 ----
部件X
部件Y

Process finished with exit code 0

建造者模式实在当创建复杂对象的算法应该独立于该对象的组成部分以及它们的装配方式时适用的模式。

 

参考《大话设计模式》