Fusion

Instructions（模块说明）

Fusion has a set of capabilities for changing method execution, including modifying return values, conditional execution with failure feedback.

Fusion具有改变方法执行的一系列功能，包含修改返回值、条件执行与失败反馈。

Dependencies（依赖）

<dependency>
  <groupId>com.github.yizzuide</groupId>
  <artifactId>milkomeda-spring-boot-starter</artifactId>
  <version>${milkomeda-last-version}</version>
</dependency>

Enable with annotation（启用模块）

@EnableFusion
@SpringBootApplication
public class MilkomedaDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(MilkomedaDemoApplication.class, args);
    }
}

Example of change return value（修改返回值案例）

1. Register fusion handler

// Add the `@FusionHandler` annotation to the class to implement the self-registration of the processor
// 在类上添加注解 `@FusionHandler`以实现处理器的自注册
@FusionHandler
public class APIResponseDataHandler {
    // Add the `@FusionAction` on method, `tag` of attribute method used for classification processing, method parameter must be `FusionMetaData`
    // 在方法上添加`@FusionAction`注解，它的属性方法`tag`用于多分类处理，方法参数必须为`FusionMetaData`类型
    @FusionAction(tag = "api")
    public ReturnVO<?> apiAction(FusionMetaData<Product> metaData) {
        // Return error if build with `FusionConverter.buildError`
        // 如果使用`FusionConverter.buildError`构建的返回，就是失败类型的返回
        if (metaData.isError()) {
            return new ReturnVO<>().error(metaData.getMsg());
        }
        return new ReturnVO<>().ok(metaData.getReturnData());
    }
}

2. Usage（使用例子）

    // The modified method must return an Object
    @Fusion(tag = "api")
    @RequestMapping("product/pull")
    public Object pull() {
        // Return success data
        // 返回成功的数据
        // return productService.pull();
        // Return error
        // 返回错误
        return FusionConverter.buildError("query fail");
    }

Example of conditional execution（条件执行案例）

The allowed and fallback attribute method of @Fusion are support Spring EL，which first is condition, second is invoke method, fallback will invoke replace original if allowed is return false.

@Fusion注解的属性allowed和fallback都支持Spring EL，第一个是条件表达式，第二个方法调用。如果allowed返回为false，源业务方法会被替换为fallback指定的方法调用

@Slf4j
@Service("productService")
public class ProductServiceImpl implements ProductService {
    @Fusion(allowed = "@env.get('spring.profiles.active') == 'prod'", fallback = "@productService.pushNotCheck(#product, #delay)")
    @Override
    public void push(Product product, boolean delay) {
        log.info("push product：{}", product.getName());
    }

   public void pushNotCheck(Product product, boolean delay) {
        log.info("Not push at dev environment：{}, product.getName());
   }
}