Dubbo-spi-demo與Adaptive使用

建立API子產品-dubbo-spi-demo-api

• api添加依賴

<dependencies>
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo</artifactId>
            <version>2.7.5</version>
        </dependency>
    </dependencies>


           

• 建立Service-添加spi注解

@SPI
public interface HelloService {

    String  sayHello();
}

           

• 建立實作-依賴上面的子產品

  

public class DogHelloServiceImpl implements HelloService {
    @Override
    public String sayHello() {
        return "hello dog";
    }
}
public class HumanHelloServiceImpl implements HelloService {

    @Override
    public String sayHello() {
        return "hello Human";
    }
}


           

• 在resources目錄下建立META-INF/dubbo目錄

  

  檔案名就是接口名-内容key=value

dog=com.liu.service.impl.DogHelloServiceImpl
human=com.liu.service.impl.HumanHelloServiceImpl
           

• 測試

ExtensionLoader<HelloService> extensionLoader = ExtensionLoader.getExtensionLoader(HelloService.class);


        Set<String> supportedExtensions = extensionLoader.getSupportedExtensions();

        supportedExtensions.forEach(s->{
            System.out.println(extensionLoader.getExtension(s).sayHello());
        });
           

hello dog

hello Human

• 添加spi預設-在接口上

@SPI("dog")
public interface HelloService {

    String  sayHello();
}


           

• 測試修改

public static void main(String[] args) {

        ExtensionLoader<HelloService> extensionLoader = ExtensionLoader.getExtensionLoader(HelloService.class);


        Set<String> supportedExtensions = extensionLoader.getSupportedExtensions();

        supportedExtensions.forEach(s->{
            System.out.println(extensionLoader.getExtension(s).sayHello());
        });

        System.out.println("===============");
        HelloService defaultExtension = extensionLoader.getDefaultExtension();
        System.out.println(defaultExtension.sayHello());

    }
}

           

hello dog

hello Human

===============

hello dog

getDefaultExtension可以擷取預設配置的是哪個接口實作

• JDK 标準的 SPI 會一次性執行個體化擴充點所有實作，如果有擴充實作初始化很耗時，但如果沒用上也加

  載，會很浪費資源

• 如果有擴充點加載失敗，則所有擴充點無法使用

Adaptive

@SPI("dog")
public interface HelloService {

    String  sayHello();

    @Adaptive
    String sayHello(URL url);
}

public class DogHelloServiceImpl implements HelloService {
    @Override
    public String sayHello() {
        return "hello dog";
    }

    @Override
    public String sayHello(URL url) {
        return "hello dog : "+url;
    }
}

public class HumanHelloServiceImpl implements HelloService {

    @Override
    public String sayHello() {
        return "hello Human";
    }

    @Override
    public String sayHello(URL url) {
        return "hello Human   "+url;
    }
}


           

public class AdaptiveMain {
    public static void main(String[] args) {
        /**
         * 這裡注意?後面
         * hello.service=HelloService
         * =後面就是在配置檔案中的key
         */
        URL   url  = URL.valueOf("test://localhost/hello?hello.service=human");
        ExtensionLoader<HelloService> extensionLoader = ExtensionLoader.getExtensionLoader(HelloService.class);

        HelloService helloService = extensionLoader.getAdaptiveExtension();

        System.out.println(helloService.sayHello(url));
    }
}

           

hello Human test://localhost/hello?hello.service=human

如果不寫就調用@SPI注解配置的，

public class AdaptiveMain {
    public static void main(String[] args) {
        /**
         * 這裡注意?後面
         * hello.service=HelloService
         * =後面就是在配置檔案中的key
         * ?hello.service=human
         */
        URL   url  = URL.valueOf("test://localhost/hello");
        ExtensionLoader<HelloService> extensionLoader = ExtensionLoader.getExtensionLoader(HelloService.class);

        HelloService helloService = extensionLoader.getAdaptiveExtension();

        System.out.println(helloService.sayHello(url));
    }
}
           

hello dog : test://localhost/hello