工厂设计模式
2. 工厂设计模式
工厂模式分为三种更加细分的类型:简单工厂、工厂方法和抽象工厂。
2.1 如何实现工厂模式
2.1.1 简单工厂(Simple Factory)
简单工厂叫作静态工厂方法模式(Static Factory Method Pattern)。
现在有一个场景,需要一个资源加载器,根据不同的url进行资源加载,如果将所有的加载实现代码全部封装在了一个load方法中,就会导致一个类很大,同时扩展性也非常差,当要添加新的前缀解析其他类型的url时,发现需要修改大量的源代码,首先定义两个之后会用到的类:
*** 类描述:资源类** @Author crysw* @Version 1.0* @Date 2023/11/14 20:41*/
@AllArgsConstructor
@NoArgsConstructor
@Data
public class Resource {private String url;
}// 加载资源异常
public class ResourceLoadException extends RuntimeException {public ResourceLoadException() {super("加载资源发生异常");}public ResourceLoadException(String message) {super(message);}
}
源码如下:
/*** 类描述:加载资源的处理类** @Author crysw* @Version 1.0* @Date 2023/11/14 20:44*/
public class ResourceLoader {/*** 加载资源,获取资源对象** @param url* @return*/public Resource load(String url) {String prefix = getPrefix(url);if (Objects.equals("http", prefix)) {// 下载资源return new Resource(url);} else if (Objects.equals("file", prefix)) {// 文件流资源return new Resource(url);} else if (Objects.equals("classpath", prefix)) {// 类路径下的资源return new Resource(url);} else {return new Resource(("default"));}}/*** 获取资源路径的前缀** @param url* @return*/private String getPrefix(String url) {if (url == null || StringUtils.isEmpty(url) || !url.contains(":")) {throw new ResourceLoadException("此资源url不合法");}String[] split = url.split(":");return split[0];}
}
上面案例中的ResourceLoader#load存在很多的if分支,如果分支数量不多且不需要扩展,这样的编写方式可以接受。在实际的工作场景中,我们的业务代码可能会很多,分支逻辑也可能十分复杂,这个时候简单工厂设计模式就要发挥作用了。
不管有多少个分支逻辑,他的本质就是需要创造一个资源产品,我们只需要创建一个工厂类,将创建资源的能力交给工厂即可:
/*** 类描述:资源工厂** @Author crysw* @Version 1.0* @Date 2023/11/14 20:51*/
public class ResourceFactory {// 使用简单工厂模式(静态工厂方法模式),创建资源对象public static Resource create(String prefix, String url) {if (Objects.equals("http", prefix)) {// 下载资源return new Resource(url);} else if (Objects.equals("file", prefix)) {// 文件流资源return new Resource(url);} else if (Objects.equals("classpath", prefix)) {// 类路径下的资源return new Resource(url);} else {return new Resource(("default"));}}
}
我们将【创建资源产品】这个单一的能力赋予上面的产品工厂,这样能更好的符合单一原则。有了简单工厂之后,加载资源ResourceLoader#load的逻辑可以这样简化:
/*** 类描述:加载资源的处理类** @Author crysw* @Version 1.0* @Date 2023/11/14 20:44*/
public class ResourceLoader {/*** 优化,使用简单工厂模式的资源工厂类{@link ResourceFactory#create(String, String)}来创建资源对象** @param url* @return*/public Resource load(String url) {String prefix = getPrefix(url);// 根据前缀处理不同的资源return ResourceFactory.create(prefix, url);}/*** 获取资源路径的前缀** @param url* @return*/private String getPrefix(String url) {if (url == null || StringUtils.isEmpty(url) || !url.contains(":")) {throw new ResourceLoadException("此资源url不合法");}String[] split = url.split(":");return split[0];}
}
上面的案例过程就是简单工厂设计模式的应用,通过提取一个简单工厂类,将创建对象的过程交给简单工厂类、其他业务需要某个产品时,直接使用create方法根据传入的不同的类型创建不同的产品即可;
这样的好处是:
- 简单工厂将创建的过程进行封装,不需要关心创建的细节,更加符合面向对象思想
- 主要的业务逻辑不会被创建对象的代码干扰,代码更易阅读
- 产品的创建可以独立测试,将更容易测试
- 独立的工厂类只负责创建产品,更加符合单一原则
2.1.2 工厂方法(Factory Method)
如果有一天,我们的if分支逻辑不断膨胀,就有必要将 if 分支逻辑去掉,那又该怎么办呢?
比较经典的处理方法就是按照多态的实现思路,对上面的代码进行重构。我们会为每一个 Resource 创建一个独立的工厂类,将每一个实例的创建过程交给工厂类完成;
之前是一个大而全的工厂,一个工厂需要创建不同的产品,工厂方法讲究的是工厂要专而精,一个工厂只创建一种资源(产品),奔驰工厂只负责生产奔驰,宝马工厂只负责生产宝马。
回到我们的例子中,每一种url加载成不同的资源产品,那每一种资源都可以由一个独立的ResourceLoaderFactory生产,为了实现这一种场景,我们需要将生产资源的工厂类进行抽象:
/*** 接口描述:抽象工厂,资源加载的抽象** @Author crysw* @Version 1.0* @Date 2023/11/14 22:12*/
public interface IResourceLoaderFactory {Resource load(String url);
}
并为每一种资源创建与之匹配的具体实现(资源工厂):
public class ClassPathResourceLoaderFactory implements IResourceLoaderFactory {@Overridepublic Resource load(String url) {// 中间省略复杂的创建过程return new Resource(url);}
}public class DefaultResourceLoaderFactory implements IResourceLoaderFactory {@Overridepublic Resource load(String url) {// 中间省略复杂的创建过程return new Resource(url);}
}public class FileResourceLoaderFactory implements IResourceLoaderFactory {@Overridepublic Resource load(String url) {// 中间省略复杂的创建过程return new Resource(url);}
}public class HttpResourceLoaderFactory implements IResourceLoaderFactory {@Overridepublic Resource load(String url) {// 中间省略复杂的创建过程return new Resource(url);}
}
这就是工厂方法模式的典型代码实现。当需要新增一种读取资源的方式时,只需要新增一个工厂实现,并实现 IResourceLoaderFactory 接口即可。可见,工厂方法模式
比起简单工厂模式
更加符合开闭原则。
使用资源工厂的代码就变成如下:
/*** 类描述:加载资源类** @Author crysw* @Version 1.0* @Date 2023/11/14 22:20*/
public class ResourceLoader {/*** V1,加载资源,获取资源对象** @param url* @return*/public Resource load(String url) {String prefix = getPrefix(url);IResourceLoaderFactory resourceLoaderFactory = null;if (Objects.equals("http", prefix)) {// 下载资源resourceLoaderFactory = new HttpResourceLoaderFactory();} else if (Objects.equals("file", prefix)) {// 文件流资源resourceLoaderFactory = new FileResourceLoaderFactory();} else if (Objects.equals("classpath", prefix)) {// 类路径下的资源resourceLoaderFactory = new ClassPathResourceLoaderFactory();} else {resourceLoaderFactory = new DefaultResourceLoaderFactory();}return resourceLoaderFactory.load(url);}/*** 获取资源路径的前缀** @param url* @return*/private String getPrefix(String url) {if (url == null || StringUtils.isEmpty(url) || !url.contains(":")) {throw new ResourceLoadException("此资源url不合法");}String[] split = url.split(":");if (split.length > 1) {return split[0];} else {return "classpath";}}
}
ResourceLoader#load中还是存在if判断,当需要新增读取资源的场景时仍然要增加if判断,仍然不符合开闭原则。 为了解决上述的问题我们可以创建一个缓存来统一管理工厂实例,以后使用工厂就会更加的简单,代码如下:
/*** 类描述:加载资源类** @Author crysw* @Version 1.0* @Date 2023/11/14 22:20*/
public class ResourceLoader {// V2, 使用缓存管理工厂实例private static Map<String, IResourceLoaderFactory> resourceLoaderFactoryCacheV2 = new HashMap<>();static {resourceLoaderFactoryCacheV2.put("http", new HttpResourceLoaderFactory());resourceLoaderFactoryCacheV2.put("file", new FileResourceLoaderFactory());resourceLoaderFactoryCacheV2.put("classpath", new ClassPathResourceLoaderFactory());resourceLoaderFactoryCacheV2.put("default", new DefaultResourceLoaderFactory());}/*** V2,加载资源,获取资源对象。 新增场景不再需要if判断了** @param url* @return*/public Resource load2(String url) {String prefix = getPrefix(url);return resourceLoaderFactoryCacheV2.get(prefix).load(url);}/*** 获取资源路径的前缀** @param url* @return*/private String getPrefix(String url) {if (url == null || StringUtils.isEmpty(url) || !url.contains(":")) {throw new ResourceLoadException("此资源url不合法");}String[] split = url.split(":");if (split.length > 1) {return split[0];} else {return "classpath";}}
}
新增场景,版本V2仍然需要修改static中的代码,可以写一个配置文件resourceLoader.properties
,将工厂类进行配置:
http=cn.itcast.designPatterns.factoryMethod.resourceFactory.HttpResourceLoaderFactory
file=cn.itcast.designPatterns.factoryMethod.resourceFactory.FileResourceLoaderFactory
classpath=cn.itcast.designPatterns.factoryMethod.resourceFactory.ClassPathResourceLoaderFactory
default=cn.itcast.designPatterns.factoryMethod.resourceFactory.DefaultResourceLoaderFactory
static中的缓存加载优化后完全满足开闭原则,代码如下:
/*** 类描述:加载资源类** @Author crysw* @Version 1.0* @Date 2023/11/14 22:20*/
public class ResourceLoader {// V3private static Map<String, IResourceLoaderFactory> resourceLoaderFactoryCacheV3 = new HashMap<>();static {InputStream inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("resourceLoader.properties");Properties properties = new Properties();try {properties.load(inputStream);for (Map.Entry<Object, Object> entry : properties.entrySet()) {String key = entry.getKey().toString();Class clazz = Class.forName(entry.getValue().toString());IResourceLoaderFactory resourceLoaderFactory = (IResourceLoaderFactory) clazz.getConstructor().newInstance();resourceLoaderFactoryCacheV3.put(key, resourceLoaderFactory);}} catch (IOException | ClassNotFoundException | InstantiationException | IllegalAccessException |NoSuchMethodException | InvocationTargetException e) {throw new RuntimeException(e);}}/*** V3,加载资源,获取资源对象。新增场景不再需要if判断了** @param url* @return*/public Resource load3(String url) {String prefix = getPrefix(url);return resourceLoaderFactoryCacheV3.get(prefix).load(url);}/*** 获取资源路径的前缀** @param url* @return*/private String getPrefix(String url) {if (url == null || StringUtils.isEmpty(url) || !url.contains(":")) {throw new ResourceLoadException("此资源url不合法");}String[] split = url.split(":");if (split.length > 1) {return split[0];} else {return "classpath";}}
}
以后我们想新增或删除一个资源工厂只需要写一个类实现IResourceLoaderFactory接口,并在配置文件中进行配置即可。如此就完全看不到if-else的影子了。
上面的代码中产品是简单单一的Resource类,在实际工作中,我们的产品可能是及其复杂的,我们同样需要对整个产品线进行抽象。将Resource进行抽象:
/*** 类描述:资源(产品)的抽象** @Author crysw* @Version 1.0* @Date 2023/11/15 22:32*/
public abstract class AbstractResource {private String url;public AbstractResource() {}public AbstractResource(String url) {this.url = url;}protected void shared() {System.out.println("这是共享方法");}/*** 每个子类需要独自实现的方法** @return 字节流*/public abstract InputStream getInputStream();
}
具体的产品需要继承这个抽象类:
/*** 类描述:classpath资源(产品)** @Author crysw* @Version 1.0* @Date 2023/11/15 22:35*/
public class ClassPathResource extends AbstractResource {public ClassPathResource() {}public ClassPathResource(String url) {super(url);}@Overridepublic InputStream getInputStream() {return null;}
}
其他产品同理,我们的工厂类也需要面向产品的抽象进行编程:
/*** 类描述:classpath资源工厂** @Author crysw* @Version 1.0* @Date 2023/11/14 22:15*/
public class ClassPathResourceLoaderFactory2 implements IResourceLoaderFactory2 {@Overridepublic AbstractResource load(String url) {// 中间省略复杂的创建过程return new ClassPathResource(url);}
}
resourceLoader2.properties
配置工厂类:
http=cn.itcast.designPatterns.factoryMethod.resourceFactory.HttpResourceLoaderFactory2
file=cn.itcast.designPatterns.factoryMethod.resourceFactory.FileResourceLoaderFactory2
classpath=cn.itcast.designPatterns.factoryMethod.resourceFactory.ClassPathResourceLoaderFactory2
default=cn.itcast.designPatterns.factoryMethod.resourceFactory.DefaultResourceLoaderFactory2
加载资源工厂:
/*** 类描述:加载资源类** @Author crysw* @Version 1.0* @Date 2023/11/14 22:20*/
public class ResourceLoader {// V4private static Map<String, IResourceLoaderFactory2> resourceLoaderFactoryCacheV4 = new HashMap<>();static {InputStream inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("resourceLoader2.properties");Properties properties = new Properties();try {properties.load(inputStream);for (Map.Entry<Object, Object> entry : properties.entrySet()) {String key = entry.getKey().toString();Class clazz = Class.forName(entry.getValue().toString());IResourceLoaderFactory2 resourceLoaderFactory2 = (IResourceLoaderFactory2) clazz.getConstructor().newInstance();resourceLoaderFactoryCacheV4.put(key, resourceLoaderFactory2);}} catch (IOException | ClassNotFoundException | InstantiationException | IllegalAccessException |NoSuchMethodException | InvocationTargetException e) {throw new RuntimeException(e);}}/*** V4,加载资源,获取资源对象。抽象资源(产品)** @param url* @return*/public AbstractResource load4(String url) {return resourceLoaderFactoryCacheV4.get(getPrefix(url)).load(url);}/*** 获取资源路径的前缀** @param url* @return*/private String getPrefix(String url) {if (url == null || StringUtils.isEmpty(url) || !url.contains(":")) {throw new ResourceLoadException("此资源url不合法");}String[] split = url.split(":");if (split.length > 1) {return split[0];} else {return "classpath";}}
}
我们编写测试用例进行测试:
/*** 类描述:设计模式的测试用例** @Author crysw* @Version 1.0* @Date 2023/11/6 22:43*/
@Slf4j
public class DesignPatternTest {@Testpublic void testFactoryMethod() {String url = "file://D://a.txt";// 测试简单工厂ResourceLoader resourceLoader = new cn.itcast.designPatterns.simpleFactory.ResourceLoader();Resource resource = resourceLoader.load(url);log.info("resource --> {}", resource.getClass().getName());// 测试工厂方法cn.itcast.designPatterns.factoryMethod.ResourceLoader resourceLoader1 = new cn.itcast.designPatterns.factoryMethod.ResourceLoader();Resource resource1 = resourceLoader1.load3(url);log.info("resource --> {}", resource.getClass().getName());// 测试工厂方法,抽象资源(产品)String url2 = "classpath:resourceLoader2.properties";AbstractResource abstractResource = resourceLoader1.load4(url2);log.info("resource --> {}", abstractResource.getClass().getName());// 解决此处SLF4J的打日志的问题:https://www.cnblogs.com/fangjb/p/12964710.html}
}
测试结果:
[main] INFO cn.itcast.designPattern.DesignPatternTest - resource --> cn.itcast.designPatterns.simpleFactory.Resource
[main] INFO cn.itcast.designPattern.DesignPatternTest - resource --> cn.itcast.designPatterns.simpleFactory.Resource
[main] INFO cn.itcast.designPattern.DesignPatternTest - resource --> cn.itcast.designPatterns.factoryMethod.product.ClassPathResource
2.1.3 抽象工厂(Abstract Factory)
为创建一组相关或者相互依赖的对象提供一个接口,而且无须指定他们的具体类。
抽象工厂模式是工厂方法模式的升级版本,在有多个业务品种、业务分类时,通过抽象工厂模式生产需要的对象。
在简单工厂和工厂方法中,往往只需要创建一种类型的产品
,但是如果需求改变,需要增加多种类型的产品
,即增加产品族
,假设需求是创建各种类型的资源,我们在上面案例的基础上再增加一个维度,如图片资源、视频资源、文本资源等。
为了管理产品族,将资源(产品)进行抽象, 抽象出picture,text,video产品的抽象资源类,都实现Resource接口。
/*** 接口描述:资源(产品)抽象接口** @Author crysw* @Version 1.0* @Date 2023/11/16 21:55*/
public interface Resource {/*** 读取资源,返回流对象** @param url* @return*/InputStream getStream(String url);
}/*** 类描述:picture资源(产品)的抽象,产品族** @Author crysw* @Version 1.0* @Date 2023/11/16 22:00*/
public class AbstractPictureResource implements Resource {// 图片的一些公用的成员变量,方法都可以定义在这个类中private String url;public AbstractPictureResource() {}public AbstractPictureResource(String url) {this.url = url;}@Overridepublic InputStream getStream(String url) {try {return new FileInputStream(url);} catch (FileNotFoundException e) {throw new RuntimeException(e);}}
}public class AbstractTextResource implements Resource {// text文本的一些公用的成员变量,方法都可以定义在这个类中private String url;public AbstractTextResource() {}public AbstractTextResource(String url) {this.url = url;}@Overridepublic InputStream getStream(String url) {try {return new FileInputStream(url);} catch (FileNotFoundException e) {throw new RuntimeException(e);}}
}public class AbstractVideoResource implements Resource {// 视频video的一些公用的成员变量,方法都可以定义在这个类中private String url;public AbstractVideoResource() {}public AbstractVideoResource(String url) {this.url = url;}@Overridepublic InputStream getStream(String url) {try {return new FileInputStream(url);} catch (FileNotFoundException e) {throw new RuntimeException(e);}}
}
再来看看抽象资源(产品)的具体实现, 根据不同类型编写对于的具体实现:
/*** 类描述:classpath图片资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:11*/
@Slf4j
public class ClassPathPictureResource extends AbstractPictureResource {public ClassPathPictureResource() {}public ClassPathPictureResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}/*** 类描述:classpath文本资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:34*/
@Slf4j
public class ClassPathTextResource extends AbstractTextResource {public ClassPathTextResource() {}public ClassPathTextResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}/*** 类描述:classpath视频资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:32*/
@Slf4j
public class ClassPathVideoResource extends AbstractVideoResource {public ClassPathVideoResource() {}public ClassPathVideoResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}/*** 类描述:默认图片资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:11*/
@Slf4j
public class DefaultPictureResource extends AbstractPictureResource {public DefaultPictureResource() {}public DefaultPictureResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}
/*** 类描述:默认文本资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:34*/
@Slf4j
public class DefaultTextResource extends AbstractTextResource {public DefaultTextResource() {}public DefaultTextResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}/*** 类描述:默认视频资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:32*/
@Slf4j
public class DefaultVideoResource extends AbstractVideoResource {public DefaultVideoResource() {}public DefaultVideoResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {return super.getStream(url);}
}
/*** 类描述:file图片资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:11*/
@Slf4j
public class FilePictureResource extends AbstractPictureResource {public FilePictureResource() {}public FilePictureResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}
/*** 类描述:file文本资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:34*/
@Slf4j
public class FileTextResource extends AbstractTextResource {public FileTextResource() {}public FileTextResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}
/*** 类描述:file视频资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:32*/
@Slf4j
public class FileVideoResource extends AbstractVideoResource {public FileVideoResource() {}public FileVideoResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}/*** 类描述:http图片资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:11*/
@Slf4j
public class HttpPictureResource extends AbstractPictureResource {public HttpPictureResource() {}public HttpPictureResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}/*** 类描述:http文本资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:34*/
@Slf4j
public class HttpTextResource extends AbstractTextResource {public HttpTextResource() {}public HttpTextResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}/*** 类描述:http视频资源** @Author crysw* @Version 1.0* @Date 2023/11/16 22:32*/
@Slf4j
public class HttpVideoResource extends AbstractVideoResource {public HttpVideoResource() {}public HttpVideoResource(String url) {super(url);}@Overridepublic InputStream getStream(String url) {log.info(">>>{}, url: {}", this.getClass().getSimpleName(), url);return super.getStream(url);}
}
抽象资源工厂:
/*** 接口描述:抽象工厂,每一个工厂实例都可以生产一个产品族** @Author crysw* @Version 1.0* @Date 2023/11/14 22:12*/
public interface IResourceLoaderFactory {/*** 加载图片资源的工厂方法** @param url* @return*/AbstractPictureResource loadPcitureResource(String url);/*** 加载视频资源的工厂方法** @param url* @return*/AbstractVideoResource loadVideoResource(String url);/*** 加载文本资源的工厂方法** @param url* @return*/AbstractTextResource loadTextResource(String url);
}/*** 类描述:抽象的工厂** @Author crysw* @Version 1.0* @Date 2023/11/16 22:23*/
public abstract class AbstractResourceLoaderFactory implements IResourceLoaderFactory {// 可以提供共享的方法、模板、共享的变量资源等
}
根据不同的url类型编写具体的资源工厂实现:
/*** 类描述:classpath资源工厂的实现** @Author crysw* @Version 1.0* @Date 2023/11/16 22:16*/
public class ClasspathResourceLoaderFactory extends AbstractResourceLoaderFactory {@Overridepublic AbstractPictureResource loadPcitureResource(String url) {return new ClassPathPictureResource(url);}@Overridepublic AbstractVideoResource loadVideoResource(String url) {return new ClassPathVideoResource(url);}@Overridepublic AbstractTextResource loadTextResource(String url) {return new ClassPathTextResource(url);}
}/*** 类描述:default默认资源工厂的实现** @Author crysw* @Version 1.0* @Date 2023/11/16 22:16*/
public class DefaultResourceLoaderFactory extends AbstractResourceLoaderFactory {@Overridepublic AbstractPictureResource loadPcitureResource(String url) {return new DefaultPictureResource(url);}@Overridepublic AbstractVideoResource loadVideoResource(String url) {return new DefaultVideoResource(url);}@Overridepublic AbstractTextResource loadTextResource(String url) {return new DefaultTextResource(url);}
}/*** 类描述:file资源工厂的实现** @Author crysw* @Version 1.0* @Date 2023/11/16 22:16*/
public class FileResourceLoaderFactory extends AbstractResourceLoaderFactory {@Overridepublic AbstractPictureResource loadPcitureResource(String url) {return new FilePictureResource(url);}@Overridepublic AbstractVideoResource loadVideoResource(String url) {return new FileVideoResource(url);}@Overridepublic AbstractTextResource loadTextResource(String url) {return new FileTextResource(url);}
}/*** 类描述:http资源工厂的实现** @Author crysw* @Version 1.0* @Date 2023/11/16 22:16*/
public class HttpResourceLoaderFactory extends AbstractResourceLoaderFactory {@Overridepublic AbstractPictureResource loadPcitureResource(String url) {return new HttpPictureResource(url);}@Overridepublic AbstractVideoResource loadVideoResource(String url) {return new HttpVideoResource(url);}@Overridepublic AbstractTextResource loadTextResource(String url) {return new HttpTextResource(url);}
}
resourceLoader3.properties
http=cn.itcast.designPatterns.abstractFactory.resourceFactory.impl.HttpResourceLoaderFactory
file=cn.itcast.designPatterns.abstractFactory.resourceFactory.impl.FileResourceLoaderFactory
classpath=cn.itcast.designPatterns.abstractFactory.resourceFactory.impl.ClasspathResourceLoaderFactory
default=cn.itcast.designPatterns.abstractFactory.resourceFactory.impl.DefaultResourceLoaderFactory
使用资源工厂加载资源:
/*** 类描述:加载资源类** @Author crysw* @Version 1.0* @Date 2023/11/19 17:04*/
public class ResourceLoader {private static Map<String, IResourceLoaderFactory> resourceLoaderFactoryCache = new HashMap<>();static {InputStream inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("resourceLoader3.properties");Properties properties = new Properties();try {properties.load(inputStream);for (Map.Entry<Object, Object> entry : properties.entrySet()) {String key = (String) entry.getKey();Class<?> clazz = Class.forName(entry.getValue().toString());IResourceLoaderFactory resourceLoaderFactory = (IResourceLoaderFactory) clazz.getConstructor().newInstance();resourceLoaderFactoryCache.put(key, resourceLoaderFactory);}} catch (IOException | ClassNotFoundException | NoSuchMethodException | InstantiationException |IllegalAccessException | InvocationTargetException e) {throw new RuntimeException(e);}}/*** 加载picture资源** @param url* @return*/public AbstractPictureResource loadPictureResource(String url) {return resourceLoaderFactoryCache.get(getPrefix(url)).loadPcitureResource(getUrl(url));}/*** 加载视频资源** @param url* @return*/public AbstractVideoResource loadVideoResource(String url) {return resourceLoaderFactoryCache.get(getPrefix(url)).loadVideoResource(getUrl(url));}/*** 加载文本资源** @param url* @return*/public AbstractTextResource loadTextResource(String url) {return resourceLoaderFactoryCache.get(getPrefix(url)).loadTextResource(getUrl(url));}/*** 获取资源路径的前缀** @param url* @return*/private String getPrefix(String url) {if (url == null || StringUtils.isEmpty(url) || !url.contains(":")) {throw new ResourceLoadException("此资源url不合法");}String[] split = url.split(":");if (split.length > 1) {return split[0];} else {return "classpath";}}/*** 获取正确的url路径** @param url* @return*/public String getUrl(String url) {if (url == null || StringUtils.isEmpty(url) || !url.contains(":")) {throw new ResourceLoadException("此资源url不合法");}return url.substring(url.indexOf("://") + "://".length());}
}
测试抽象工厂:
@Test
public void testAbstractFactory() {String url = "file://D:/Personal/note.txt";cn.itcast.designPatterns.abstractFactory.resourceFactory.ResourceLoader resourceLoader = new cn.itcast.designPatterns.abstractFactory.resourceFactory.ResourceLoader();log.info(">>>{}", resourceLoader.loadPictureResource(url).getStream(resourceLoader.getUrl(url)));log.info(">>>{}", resourceLoader.loadVideoResource(url).getStream(resourceLoader.getUrl(url)));log.info(">>>{}", resourceLoader.loadTextResource(url).getStream(resourceLoader.getUrl(url)));}
测试结果:
[main] INFO cn.itcast.designPatterns.abstractFactory.product.impl.FilePictureResource - >>>FilePictureResource, url: D:/Personal/note.txt
[main] INFO cn.itcast.designPattern.DesignPatternTest - >>>java.io.FileInputStream@1f554b06
[main] INFO cn.itcast.designPatterns.abstractFactory.product.impl.FileVideoResource - >>>FileVideoResource, url: D:/Personal/note.txt
[main] INFO cn.itcast.designPattern.DesignPatternTest - >>>java.io.FileInputStream@131276c2
[main] INFO cn.itcast.designPatterns.abstractFactory.product.impl.FileTextResource - >>>FileTextResource, url: D:/Personal/note.txt
[main] INFO cn.itcast.designPattern.DesignPatternTest - >>>java.io.FileInputStream@711f39f9
2.2 源码应用
//todo