java spi实现案例

简介

SPI（Service Provider Interface），是JDK内置的一种 服务提供发现机制，可以用来扩展和替换组件，主要是被框架的开发人员使用。

 

核心代码

spi接口定义

public interface UserSpi {

    /**
     * 获取用户信息
     *
     * @param id 用户ID
     * @return 用户信息
     */
    User getUserById(Long id);
}

 

spi实现提供者1

 <!-- 引入spi -->
    <dependencies>
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>spi</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

public class UserSpiImpl1 implements UserSpi {
    @Override
    public User getUserById(Long id) {
        return new User(1L, "张三");
    }
}

 

 

 

spi实现提供者2

 <!-- 引入spi -->
    <dependencies>
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>spi</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

public class UserSpiImpl2 implements UserSpi {
    @Override
    public User getUserById(Long id) {
        return new User(2L, "李四");
    }
}

 

 

 

使用者测试

<!-- spi定义模块 -->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>spi</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <!-- spi实现模块1 -->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>spi-impl1</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <!-- spi实现模块2 -->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>spi-impl2</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

 

public class Test {

    public static void main(String[] args) {
        ServiceLoader<UserSpi> s = ServiceLoader.load(UserSpi.class);
        Iterator<UserSpi> iterator = s.iterator();
        while (iterator.hasNext()) {
            //如果存在多个实现类，则会遍历调用
            UserSpi userSpi = iterator.next();
            User user = userSpi.getUserById(1L);
            System.out.println(user);
        }

    }
}

 

 

源码

github: https://github.com/hdwang123/spitest

 

参考文章

https://blog.csdn.net/weixin_45987961/article/details/121052452

https://blog.csdn.net/qq_35958391/article/details/123406879

https://blog.csdn.net/jjclove/article/details/124379195