介绍建造者模式

建造者模式

将一个复杂对象的创建与它的表示分离，使得同样的构建过程可以创建不同的表示

四种角色

1. Product 产品角色 指的是一个具体的产品对象
2. Builder 抽象建造者 创建一个产品对象的各个部件的接口/抽象类
3. ConcreteBuilder 具体建造者 实现或继承抽象建造者接口 具体的构建和装配各个部件
4. Director 指挥者 构建一个使用Builder接口的对象，主要用于创建一个复杂的对象，负责指挥构建一个工程，决定了工程如何构建，按照什么顺序构建

场景

• 需要生成的对象具有复杂的内部结构
• 需要生成的对象内部属性本身相互依赖
• 与不可变对象配合使用

优点

• 建造者独立，易于扩展
• 便于控制细节风险

实现

使用继承的方式实现

public class ExtendTest {public static void main(String[] args) {AbstractBook book = new MacBookPro();book.produceBook();System.out.println("========================================");book = new XiaoMiBook();book.produceBook();}
}
// 定义一个抽象类
abstract class AbstractBook {public abstract void fillwithCpu();public abstract void fillwithGpu();public void produceBook() {fillwithCpu();fillwithGpu();}
}
// 定义具体实现类1
class MacBookPro extends AbstractBook {@Overridepublic void fillwithCpu() {System.out.println("我是高端的MacBook Pro，我使用的是迄今为止地表最强的M2 MAX芯片，我可太快太牛逼了...");}@Overridepublic void fillwithGpu() {System.out.println("我是高端的MacBook Pro，我使用的是迄今为止地表最强的M2 MAX GPU，对图形这块，我可是没输过...");}
}
// 定义具体实现类2
class XiaoMiBook extends AbstractBook {@Overridepublic void fillwithCpu() {System.out.println("我是小米笔记本，我的CPU是还不错的13代英特尔酷睿i5处理器...");}@Overridepublic void fillwithGpu() {System.out.println("我是小米笔记本，我的GPU是还不错的Geforce GTX3050Ti...");}
}

使用建造者模式

public class BuilderTest2 {public static void main(String[] args) {Book build = new BookBuilder().buildTotalPage(1).buildTotalWord(2).build();System.out.println(build);Book build2 = new BookBuilder().buildTotalPage(3).buildTotalWord(4).build();System.out.println(build2);}
}class Book{private Integer totalPage;private Integer totalWord;public Book(){}public Book(BookBuilder builder){this.totalPage = builder.totalPage;this.totalWord = builder.totalWord;}public String toString(){return "Book[totalPage="+this.totalPage+",totalWord="+this.totalWord+"]";}
}
final class BookBuilder{public Integer totalPage;public Integer totalWord;public BookBuilder buildTotalPage(Integer totalPage) {this.totalPage = totalPage;return this;}public BookBuilder buildTotalWord(Integer totalWord) {this.totalWord = totalWord;return this;}public Book build(){return new Book(this);}
}

简化对象实现

public class BuilderTest {public static void main(String[] args) {Director director = new Director(new IphoneBuilder());MobilePhone construct = director.construct();System.out.println(construct);Director director1 = new Director(new SanXinBuilder());MobilePhone construct1 = director1.construct();System.out.println(construct1);}
}@Getter
@Setter
class MobilePhone{private String name;private String cpu;private String screen;public MobilePhone(){}@Overridepublic String toString(){return this.name+"-"+this.cpu+"-"+this.screen;}
}
// 定义builder接口
abstract class Builder {public static final MobilePhone mobilePhone = new MobilePhone();private String name;private String cpu;private String screen;abstract void buildName();abstract void buildCpu();abstract void buildScreen();public MobilePhone createPhone(){return mobilePhone;}
}
class IphoneBuilder extends Builder{@Overridepublic void buildName() {mobilePhone.setName("iphoneName");}@Overridepublic void buildCpu() {mobilePhone.setCpu("iphoneCpu");}@Overridepublic void buildScreen() {mobilePhone.setScreen("iphoneScreen");}@Overridepublic MobilePhone createPhone() {return mobilePhone;}
}
class SanXinBuilder extends Builder{@Overridepublic void buildName() {mobilePhone.setName("三星1.0");}@Overridepublic void buildCpu() {mobilePhone.setCpu("三星8G");}@Overridepublic void buildScreen() {mobilePhone.setScreen("三星56寸");}@Overridepublic MobilePhone createPhone() {return mobilePhone;}
}
// 创建Director 通过有参构造器注入一个具体的builder，在核心方法construct方法完成各个组件的具体组装，并返回最后组装出来的对象
class Director{private Builder builder;public Director(Builder builder){this.builder = builder;}public MobilePhone construct(){builder.buildName();builder.buildCpu();builder.buildScreen();return builder.createPhone();}
}