设计模式之四建造者模式
基本介绍
建造者模式的四个角色
1)product(产品角色):一个具体的产品对象
2)builder(抽象建造者):创建一个product对象的各个部件指定的 接口/抽象类。
3)concreteBuilder(具体建造者):实现接口,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。它主要是用于创建一个复杂的对象。它主要有两个作用,一是:隔离了客户与对象的生产过程,二是:负责控制产品对象的生产过程。
类图
案例演示
建房子,过程为打桩、砌墙、封顶;放子有各种各样的,比如普通房,高楼,别墅,各种房子过程一样,但是要求不同。
传统做法
代码演示:
package com.hy.builder; /** * @author hanyong * @date 2020/11/10 0:28 */ public abstract class AbstractHouse { public abstract void buildBasic(); public abstract void buildWalls(); public abstract void roofed(); public void build() { buildBasic(); buildWalls(); roofed(); } } package com.hy.builder; /** * @author hanyong * @date 2020/11/10 0:31 */ public class CommonHouse extends AbstractHouse { @Override public void buildBasic() { // TODO Auto-generated method stub System.out.println(" 普通房子打地基 "); } @Override public void buildWalls() { // TODO Auto-generated method stub System.out.println(" 普通房子砌墙 "); } @Override public void roofed() { // TODO Auto-generated method stub System.out.println(" 普通房子封顶 "); } } package com.hy.builder; /** * @author hanyong * @date 2020/11/10 0:32 */ public class Client { public static void main(String[] args) { // TODO Auto-generated method stub CommonHouse commonHouse = new CommonHouse(); commonHouse.build(); } }
传统方式问题所在:没有设计缓存层对象,程序的扩展和维护不好,也就是说,这种设计方案,把产品(房子)和创建产品的过程(建房子的流程)封装在一起,耦合性增强了。
建造者模式类图
代码演示
package com.hy.builder.improve; /** * @author hanyong * @date 2020/11/10 0:45 */ public class House { private String baise; private String wall; private String roofed; public String getBaise() { return baise; } public void setBaise(String baise) { this.baise = baise; } public String getWall() { return wall; } public void setWall(String wall) { this.wall = wall; } public String getRoofed() { return roofed; } public void setRoofed(String roofed) { this.roofed = roofed; } } package com.hy.builder.improve; /** * @author hanyong * @date 2020/11/10 0:46 */ public abstract class HouseBuilder { protected House house = new House(); //将建造的流程写好, 抽象的方法 public abstract void buildBasic(); public abstract void buildWalls(); public abstract void roofed(); public House buildHouse() { return house; } } package com.hy.builder.improve; /** * @author hanyong * @date 2020/11/10 0:53 */ public class CommonHouse extends HouseBuilder { @Override public void buildBasic() { // TODO Auto-generated method stub System.out.println(" 普通房子打地基5米 "); } @Override public void buildWalls() { // TODO Auto-generated method stub System.out.println(" 普通房子砌墙10cm "); } @Override public void roofed() { // TODO Auto-generated method stub System.out.println(" 普通房子屋顶 "); } } package com.hy.builder.improve; /** * @author hanyong * @date 2020/11/10 0:49 */ public class HighBuilding extends HouseBuilder { @Override public void buildBasic() { // TODO Auto-generated method stub System.out.println(" 高楼的打地基100米 "); } @Override public void buildWalls() { // TODO Auto-generated method stub System.out.println(" 高楼的砌墙20cm "); } @Override public void roofed() { // TODO Auto-generated method stub System.out.println(" 高楼的透明屋顶 "); } } package com.hy.builder.improve; /** * @author hanyong * @date 2020/11/10 0:51 */ public class HouseDirector { HouseBuilder houseBuilder=null; //构造器传入 houseBuilder public HouseDirector(HouseBuilder houseBuilder) { this.houseBuilder = houseBuilder; } //通过setter 传入 houseBuilder public void setHouseBuilder(HouseBuilder houseBuilder) { this.houseBuilder = houseBuilder; } //如何处理建造房子的流程,交给指挥者 public House constructHouse() { houseBuilder.buildBasic(); houseBuilder.buildWalls(); houseBuilder.roofed(); return houseBuilder.buildHouse(); } } package com.hy.builder.improve; /** * @author hanyong * @date 2020/11/10 0:53 */ public class Client { public static void main(String[] args) { //盖普通房子 CommonHouse commonHouse = new CommonHouse(); //准备创建房子的指挥者 HouseDirector houseDirector = new HouseDirector(commonHouse); //完成盖房子,返回产品(普通房子) House house = houseDirector.constructHouse(); //System.out.println("输出流程"); System.out.println("--------------------------"); //盖高楼 HighBuilding highBuilding = new HighBuilding(); //重置建造者 houseDirector.setHouseBuilder(highBuilding); //完成盖房子,返回产品(高楼) houseDirector.constructHouse(); } }