2.设计模式-工厂模式（创建型）
如果没有工厂模式我们写的代码
场景
现在有一个课程，里面有Python、Java、Go语言等课程，并且每个课程都有以下业务
- 观看
- 录播
package start.service;
public interface CourseService {
// 观看
void view();
// 录屏
void record();
}
package start.service.impl;
import start.service.CourseService;
public class JavaCourseServiceImpl implements CourseService
{
@Override
public void view() {
System.out.println("观看Java");
}
@Override
public void record() {
System.out.println("录屏Java");
}
}
package start.service.impl;
import start.service.CourseService;
public class PythonCourseServiceImpl implements CourseService {
@Override
public void view() {
System.out.println("观看Python");
}
@Override
public void record() {
System.out.println("录屏Python");
}
}
package start;
import start.service.CourseService;
import start.service.impl.JavaCourseServiceImpl;
import start.service.impl.PythonCourseServiceImpl;
public class Test {
public static void main(String[] args) {
// Java、Python、Go
// 他们都有这些业务：可以观看、可以录屏
CourseService courseService = new JavaCourseServiceImpl();
courseService.view();
courseService.record();
CourseService courseService2 = new PythonCourseServiceImpl();
courseService2.view();
courseService2.record();
}
}
如果后面课程业务加了很多个课程，比如Go、C#，他们都属于课程，但是每次都要new一次对象，我们可不可以用什么方式给管理起来呢？这个时候工厂模式出现了！
简单工厂
package simple.service;
public interface CourseService {
// 观看
void view();
// 录屏
void record();
}
package simple.service.impl;
import simple.service.CourseService;
public class PythonCourseServiceImpl implements CourseService {
@Override
public void view() {
System.out.println("观看Python");
}
@Override
public void record() {
System.out.println("录屏Python");
}
}
package simple.service.impl;
import simple.service.CourseService;
public class JavaCourseServiceImpl implements CourseService
{
@Override
public void view() {
System.out.println("观看Java");
}
@Override
public void record() {
System.out.println("录屏Java");
}
}
package simple.factory;
import simple.service.CourseService;
import simple.service.impl.GoCourseServiceImpl;
import simple.service.impl.JavaCourseServiceImpl;
import simple.service.impl.PythonCourseServiceImpl;
public class CourseServiceFactory {
public static CourseService get(String name){
if("Java".equals(name)){
return new JavaCourseServiceImpl();
}else if("Python".equals(name)){
return new PythonCourseServiceImpl();
}else if("Go".equals(name)){
return new GoCourseServiceImpl();
}
return null;
}
}
package simple.factory;
import simple.service.CourseService;
public class Test {
public static void main(String[] args) {
CourseService courseService = CourseServiceFactory.get("Go");
courseService.record();
courseService.view();
}
}
虽然用简单工厂管理起来了，但是也有缺点，缺点就是每次加课程，都需要在CourseServiceFactory里添加大量的逻辑代码，所以工厂方法模式出现了！
工厂方法
package function.service;
public interface CourseService {
// 观看
void view();
// 录屏
void record();
// 编写笔记
void edit();
// 下载笔记
void download();
}
package function.service.impl;
import function.service.CourseService;
public class PythonCourseServiceImpl implements CourseService {
@Override
public void view() {
System.out.println("观看Python");
}
@Override
public void record() {
System.out.println("录屏Python");
}
@Override
public void edit() {
}
@Override
public void download() {
}
}
package function.service.impl;
import function.service.CourseService;
public class JavaCourseServiceImpl implements CourseService
{
@Override
public void view() {
System.out.println("观看Java");
}
@Override
public void record() {
System.out.println("录屏Java");
}
@Override
public void edit() {
}
@Override
public void download() {
}
}
package function.service.impl;
import function.service.CourseService;
public class GoCourseServiceImpl implements CourseService
{
@Override
public void view() {
System.out.println("观看Go");
}
@Override
public void record() {
System.out.println("录屏Go");
}
@Override
public void edit() {
}
@Override
public void download() {
}
}
package function.factory;
import function.service.CourseService;
public interface CourseServiceFactory {
CourseService create();
}
package function.factory;
import function.service.CourseService;
import function.service.impl.GoCourseServiceImpl;
public class GoCourseServiceFactory implements CourseServiceFactory{
@Override
public CourseService create() {
return new GoCourseServiceImpl();
}
}
package function.factory;
import function.service.CourseService;
import function.service.impl.JavaCourseServiceImpl;
public class JavaCourseServiceFactory implements CourseServiceFactory{
@Override
public CourseService create() {
return new JavaCourseServiceImpl();
}
}
package function.factory;
import function.service.CourseService;
import function.service.impl.PythonCourseServiceImpl;
public class PythonCourseServiceFactory implements CourseServiceFactory{
@Override
public CourseService create() {
return new PythonCourseServiceImpl();
}
}
package function.factory;
import function.service.CourseService;
public class Test {
public static void main(String[] args) {
CourseServiceFactory courseServiceFactory = new JavaCourseServiceFactory();
CourseService courseService = courseServiceFactory.create();
courseService.record();
courseService.view();
// Java、Python、Go
// 他们都有这些业务：可以观看、可以录屏、编写笔记、下载笔记
}
}
虽然每个课程都用不同的工厂去进行创建，但是他也有缺点，就是每个课程有可能有不同的业务，比如新增了编写笔记、下载笔记等等，我们都需要去进行每个课程的方法实现。并且呢，如果课程多，我们也需要创建大量的Java类，创建好多个课程共产类，越来越负责，所以这个时候抽象工厂出现了！
抽象工厂
我们给观看、录屏分组，分为视频组。编写笔记和下载笔记分为笔记组
package abstracts.service;
public interface VideoCourseService {
// 观看
void view();
// 录屏
void record();
}
package abstracts.service;
public interface NoteCourseService {
// 编写笔记
void edit();
// 下载笔记
void download();
}
package abstracts.service.Impl;
import abstracts.service.VideoCourseService;
public class PythonVideoCourseServiceImpl implements VideoCourseService
{
@Override
public void view() {
System.out.println("观看Python");
}
@Override
public void record() {
System.out.println("录制Python");
}
}
package abstracts.service.Impl;
import abstracts.service.NoteCourseService;
public class PythonNoteCourseServiceImpl implements NoteCourseService
{
@Override
public void edit() {
System.out.println("编写Python笔记");
}
@Override
public void download() {
System.out.println("下载Python笔记");
}
}
package abstracts.service.Impl;
import abstracts.service.VideoCourseService;
public class JavaVideoCourseServiceImpl implements VideoCourseService
{
@Override
public void view() {
System.out.println("观看Java");
}
@Override
public void record() {
System.out.println("录制Java");
}
}
package abstracts.service.Impl;
import abstracts.service.NoteCourseService;
public class JavaNoteCourseServiceImpl implements NoteCourseService
{
@Override
public void edit() {
System.out.println("编写Java笔记");
}
@Override
public void download() {
System.out.println("下载Java笔记");
}
}
package abstracts.factory;
import abstracts.service.NoteCourseService;
import abstracts.service.VideoCourseService;
public abstract class CourseFactory {
protected abstract NoteCourseService createNoteService();
protected abstract VideoCourseService createVideoService();
}
package abstracts.factory;
import abstracts.service.Impl.JavaNoteCourseServiceImpl;
import abstracts.service.Impl.JavaVideoCourseServiceImpl;
import abstracts.service.NoteCourseService;
import abstracts.service.VideoCourseService;
public class JavaCourseFactory extends CourseFactory{
@Override
protected NoteCourseService createNoteService() {
return new JavaNoteCourseServiceImpl();
}
@Override
protected VideoCourseService createVideoService() {
return new JavaVideoCourseServiceImpl();
}
}
package abstracts.factory;
import abstracts.service.Impl.PythonNoteCourseServiceImpl;
import abstracts.service.Impl.PythonVideoCourseServiceImpl;
import abstracts.service.NoteCourseService;
import abstracts.service.VideoCourseService;
public class PythonCourseFactory extends CourseFactory{
@Override
protected NoteCourseService createNoteService() {
return new PythonNoteCourseServiceImpl();
}
@Override
protected VideoCourseService createVideoService() {
return new PythonVideoCourseServiceImpl();
}
}
package abstracts.factory;
import abstracts.factory.JavaCourseFactory;
public class Test {
public static void main(String[] args) {
// Java、Python、Go
// 他们都有这些业务：可以观看、可以录屏、编写笔记、下载笔记
// 视频：可以观看、可以录屏
// 笔记：编写笔记、下载笔记
JavaCourseFactory javaCourseFactory = new JavaCourseFactory();
javaCourseFactory.createNoteService().edit();
javaCourseFactory.createVideoService().record();
}
}
