设计模式 -- 建造者模式（Builder pattern）_pattern builder os-优快云博客

本文链接：https://blog.youkuaiyun.com/scoryy/article/details/123637592

封装一个复杂对象的构建过程，可以按照流程来构建对象。

优点：它可以将一个复杂对象的构建与表示相分离，同一个构建过程，可以构成出不同的产品，简化了投建逻辑。
缺点：如果构建流程特别复杂，就是导致这个构建系统过于庞大，不利于控制。

// 产品类
public class Computer {
    private String cpu;//必须
    private String ram;//必须
    private int usbCount;//可选
    private String keyboard;//可选
    private String display;//可选


    public Computer(String cpu, String ram) {
        this.cpu = cpu;
        this.ram = ram;
    }
    public void setUsbCount(int usbCount) {
        this.usbCount = usbCount;
    }
    public void setKeyboard(String keyboard) {
        this.keyboard = keyboard;
    }
    public void setDisplay(String display) {
        this.display = display;
    }
    @Override
    public String toString() {
        return "Computer{" +
                "cpu='" + cpu + '\'' +
                ", ram='" + ram + '\'' +
                ", usbCount=" + usbCount +
                ", keyboard='" + keyboard + '\'' +
                ", display='" + display + '\'' +
                '}';
    }
}


// 抽象建造者
public abstract class ComputerBuilder {
    public abstract void setUsbCount();
    public abstract void setKeyboard();
    public abstract void setDisplay();


    public abstract Computer getComputer();
}


// 苹果电脑构建者类
public class MacComputerBuilder extends ComputerBuilder {
    private Computer computer;
    public MacComputerBuilder(String cpu, String ram) {
        computer = new Computer(cpu, ram);
    }
    @Override
    public void setUsbCount() {
        computer.setUsbCount(2);
    }
    @Override
    public void setKeyboard() {
        computer.setKeyboard("苹果键盘");
    }
    @Override
    public void setDisplay() {
        computer.setDisplay("苹果显示器");
    }
    @Override
    public Computer getComputer() {
        return computer;
    }
}


// 联想电脑构建者类
public class LenovoComputerBuilder extends ComputerBuilder {
    private Computer computer;
    public LenovoComputerBuilder(String cpu, String ram) {
        computer=new Computer(cpu,ram);
    }
    @Override
    public void setUsbCount() {
        computer.setUsbCount(4);
    }
    @Override
    public void setKeyboard() {
        computer.setKeyboard("联想键盘");
    }
    @Override
    public void setDisplay() {
        computer.setDisplay("联想显示器");
    }
    @Override
    public Computer getComputer() {
        return computer;
    }
}


// 指导者类（Director）
public class ComputerDirector {
    public Computer makeComputer(ComputerBuilder builder){
        builder.setUsbCount();
        builder.setDisplay();
        builder.setKeyboard();
        return builder.getComputer();
    }
}


// 使用
public static void main(String[] args) {
        ComputerDirector director=new ComputerDirector();//1
        ComputerBuilder builder=new MacComputerBuilder("I5处理器","三星125");//2
        Computer macComputer = director.makeComputer(builder);//3
        System.out.println("mac computer:"+macComputer.toString());


        ComputerBuilder lenovoBuilder=new LenovoComputerBuilder("I7处理器","海力士222");
        Computer lenovoComputer=director.makeComputer(lenovoBuilder);
        System.out.println("lenovo computer:"+lenovoComputer.toString());
}

简化版

public class Product {
    private String board;     
    private String display;     
    private String os;     
     
    public String getBoard() {
        return board;     
    }      
    
    public String getDisplay() {         
        return display;     
    }     
     
    public String getOs() {         
        return os;     
    }      
    
    private Product(Builder builder) {         
        // 进行构建         
        this.board = builder.board;         
        this.display = builder.display;         
        this.os = builder.os;     
    }     
     
    public static class Builder {         
        // 建造者模式还可以设置默认值         
        private String board = "default value";         
        private String display = "default value";         
        private String os = "default value";  
                
        public void setBoard(String board) {             
            this.board = board;         
        }         
         
        public void setDisplay(String display) {                 
            this.display = display;         
        }       
           
        public void setOs(String os) {             
            this.os = os;         
        }   
                
        public Product build() {             
            return new Product(this);         
        }     
    } 
}

根据以下文章总结：