建造者模式

拼搏现实的明天。 2021-09-24 07:52 357阅读 0赞

*  找商家买电脑：

public class Computer {
    	private String brand;
    	private String screan;
    	private String mainboard;
    	private String memory;
        
        // getter and setter
    	@Override
    	public String toString() {
    		return "Computer [brand=" + brand + ", screan=" + screan + ", mainboard=" + mainboard + ", memory=" + memory
    				+ "]";
    	}
    }

只需告诉他，你要 lenove 的电脑，他会帮你搞定。商家从厂商拿货，你从商家拿货：

class BuyComputer {
    	public static void main(String[] args) {
    		Director seller = new Director(new LenovoBuilder());
    		Computer computer = seller.build();
    		System.out.println(computer);
    	}
    }

所有厂商都是对电脑组装：

public abstract class ComputerBuilder {
    	abstract void buildBrand();
    	abstract void buildScrean();
    	abstract void buildMainboard();
    	abstract void buildMemory();
    	abstract Computer build();
    }

其中 lenovo 的厂商这样制造：

public class LenovoBuilder extends ComputerBuilder {
    	private Computer computer = new Computer();
    	@Override
    	public Computer build() {
    		return this.computer;
    	}
    	@Override
    	public void buildBrand() {
    		this.computer.setBrand("lenovo");
    	}
    	@Override
    	public void buildScrean() {
    		this.computer.setScrean("lenovo screan");
    	}
    	@Override
    	public void buildMainboard() {
    		this.computer.setMainboard("lenovo mainboard");
    	}
    	@Override
    	public void buildMemory() {
    		this.computer.setMemory("lenovo memory");
    	}
    }

商家具体做的事情就是联系厂商，及组装什么配件：

public class Director {
    	private ComputerBuilder builder;
    	public Director(ComputerBuilder builder) {
    		this.builder = builder;
    	}
    	public Computer build() {
    		this.builder.buildBrand();
    		this.builder.buildScrean();
    		this.builder.buildMainboard();
    		this.builder.buildMemory();
    		return this.builder.build();
    	}
    }

--------------------

*  自己从 JD 买电脑配件：

public static void main(String[] args) {
    		JD jd = new Computer.JD();
    		Computer computer = jd.setBrand("lenovo").setMainboard("lenovo mainboard")
    			.setMemory("suming memory").setScrean("aiguo screan")
    			.build();
    		System.out.println(computer);
    	}

具体实现：

public class Computer {
    	private String brand;
    	private String screan;
    	private String mainboard;
    	private String memory;
    	
    	private Computer() {}; // 对外屏蔽，对内开放
    	private Computer(JD jd) {
    		this.brand = jd.brand;
    		this.screan = jd.screan;
    		this.mainboard = jd.mainboard;
    		this.memory = jd.memory;
    	}
    	
    	public static final class JD {
    		private String brand;
    		private String screan;
    		private String mainboard;
    		private String memory;
    		
    		public Computer build() {
    			return new Computer(this);
    		}
    		
    		public JD setBrand(String brand) {
    			this.brand = brand;
    			return this;
    		}
    		public JD setScrean(String screan) {
    			this.screan = screan;
    			return this;
    		}
    		public JD setMainboard(String mainboard) {
    			this.mainboard = mainboard;
    			return this;
    		}
    		public JD setMemory(String memory) {
    			this.memory = memory;
    			return this;
    		}
    	}
    	
    	@Override
    	public String toString() {
    		return "Computer [brand=" + brand + ", screan=" + screan + ", mainboard=" + mainboard + ", memory=" + memory
    				+ "]";
    	}
    	
    }