详解java构建者模式Builder

package com.example.myjavademo;
 
/**
 * 计算机的组装过程较为复杂，并且组装过程不固定，为了易于理解，我们把计算机组装过程简化为
 * 构建主机、设置操作系统、设置显示器3步，然后通过Directer和具体Builder来构建计算机对象
 *
 */
public class BuilderDesignDemo {
 public static void main(String []args){
 //方式一
 Builder builder=new MACBookBuilder();
 Director director=new Director(builder);
 director.construct("intel","AOC");
 System.out.println(builder.create().toString());
 
 
 //方式2
 System.out.println(new MACBookBuilder().
  buildBoard("intel").buildDisplay("AOC").create().toString());
 
 
 }
}
 
/**
 * 计算机抽象类，即Product角色
 */
abstract class Computer{
 
 protected String mBoard;
 protected String mDisplay;
 protected String mOS;
 protected Computer(){
 
 }
 public void setBoard(String board){//具体什么实现进行了隐藏
 
 this.mBoard=board;
 }
 public void setDisplay(String display){//具体什么实现进行了隐藏
 this.mDisplay=display;
 }
 public abstract void setOS();
 
 @Override
 public String toString() {
 return "Computer:="+mBoard+",="+mOS+",="+mDisplay;
 }
}
 
/**
 * 具体的Computer类
 */
 
class MACBook extends Computer{
 protected MACBook(){};
 @Override
 public void setOS() {
 mOS="MAC OS X";
 }
}
 
/**
 * 抽象Builder类
 */
abstract class Builder{
 //设置主机
 public abstract Builder buildBoard(String board);
 //设置操作系统
 public abstract Builder buildOS();
 //设置显示器
 public abstract Builder buildDisplay(String display);
 //创建Computer
 public abstract Computer create();
}
 
/**
 * 具体Builder类，MACBookBuilder
 */
class MACBookBuilder extends Builder{
 private Computer computer=new MACBook();
 
 @Override
 public Builder buildBoard(String board) {
 computer.setBoard(board);
 return this;
 }
 
 @Override
 public Builder buildOS() {
 computer.setOS();
 return this;
 }
 
 @Override
 public Builder buildDisplay(String display) {
 computer.setDisplay(display);
 return this;
 }
 
 @Override
 public Computer create() {//Mac的操作系统肯定是MAC OS的；这部分对外部隐藏
 computer.setOS();
 return computer;
 }
}
 
/**
 * Director类，负责构建Computer
 */
class Director{
 Builder builder=null;
 
 public Director(Builder builder) {
 this.builder = builder;
 }
 /**
 * 构建对象
 */
 public void construct(String board,String display){
 builder.buildBoard(board);
 builder.buildDisplay(display);
 
 }
}