java的SPI机制和Dubbo的SPI机制

心已赠人 2022-12-27 01:19 175阅读 0赞

## java的SPI机制和Dubbo的SPI机制 ##

#### 简介 ####

SPI ，全称为 Service Provider Interface，是一种服务发现机制。它通过在ClassPath路径下的META-INF/services文件夹查找文件，自动加载文件里所定义的类。

#### Java的SPI实现 ####

1.接口，Hello

package com.ls.spi.jdk;
    
    /** * Created by ls on 2020/12/6. */
    public interface Hello { 
      void sayHi();
    }

2.下面是两个实现类

package com.ls.spi.jdk;
    
    /** * Created by ls on 2020/12/6. */
    public class GoHello implements Hello { 
    
      @Override
      public void sayHi() { 
        System.out.println("go hello");
      }
    }

package com.ls.spi.jdk;
    
    /** * Created by ls on 2020/12/6. */
    public class JavaHello implements Hello { 
    
      @Override
      public void sayHi() { 
        System.out.println("java hello");
      }
    }

package com.ls.spi.jdk;
    
    import java.util.ServiceLoader;
    
    /** * Created by ls on 2020/12/6. */
    public class TestRun { 
    
      public static void main(String[] args) { 
        ServiceLoader<Hello> load = ServiceLoader.load(Hello.class);
        load.forEach(Hello::sayHi);
      }
    }

5.在classpath下创建META-INF/services的文件，创建文件名为：com.ls.spi.jdk.Hello：如下图  
![在这里插入图片描述][2020120619321948.png]  
**6.运行结果**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0_size_16_color_FFFFFF_t_70]

## Dubbo的SPI ##

官网：http://dubbo.apache.org/zh/docs/v2.7/dev/impls/protocol/  
案例实现：

@SPI
    public interface ISend { 
    
      void send();
    
    }

public class QqSend implements ISend{ 
    
      @Override
      public void send() { 
        System.out.println("qq");
      }
    }

public class WxSend implements ISend{ 
    
      @Override
      public void send() { 
        System.out.println("wx");
      }
    }

public class TestRun { 
    
      public static void main(String[] args) { 
        ExtensionLoader<ISend> extensionLoader = ExtensionLoader.getExtensionLoader(ISend.class);
        ISend qq = extensionLoader.getExtension("qq");
        qq.send();
      }
    }

配置文件：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0_size_16_color_FFFFFF_t_70 1]

运行结果：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0_size_16_color_FFFFFF_t_70 2]  
Maven依赖

<dubbo.version>2.7.7</dubbo.version>
        
        <dependency>
          <groupId>org.apache.dubbo</groupId>
          <artifactId>dubbo</artifactId>
          <version>${dubbo.version}</version>
        </dependency>
        <dependency>
          <groupId>org.apache.dubbo</groupId>
          <artifactId>dubbo-dependencies-zookeeper</artifactId>
          <version>${dubbo.version}</version>
        </dependency>

[2020120619321948.png]: /images/20221120/f189a625dffc4bc7938416827ed89274.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20201206193420766.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20201206194215663.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20201206193727468.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMTk4MDA0,size_16,color_FFFFFF,t_70