provider泛型类型为Float时返回Double类型

[natsumm]

• [X] I have searched the issues of this repository and believe that this is not a duplicate.

Environment

• Dubbo version: 3.0.7
• Operating System version: Linux Ubuntu-20.04
• Java version: 1.8

Steps to reproduce this issue

1. provider返回泛型为Float
2. consumer以Float接收返回参数

Demo地址: https://github.com/natsumm/dubbo-generic-float-issue

Expected Behavior

返回Float类型参数

Actual Behavior

返回了Double类型参数，并抛出java.lang.ClassCastException

Detail

1. provider端代码

@DubboService
public class DemoServiceImpl implements DemoService {

    @Override
    public String sayHello(String name) {
        return "Hello " + name;
    }

    //此处定义为Float类型
    @Override
    public List<Float> getFloats() {
        List<Float> floats = new ArrayList<>();
        floats.add(35.3F);
        floats.add(45.1F);
        return floats;
    }
}

2. consumer端代码

@SpringBootApplication
@Service
@EnableDubbo
public class ConsumerApplication {

    @DubboReference
    private DemoService demoService;

    public static void main(String[] args) {

        ConfigurableApplicationContext context = SpringApplication.run(ConsumerApplication.class, args);
        ConsumerApplication application = context.getBean(ConsumerApplication.class);
        String result = application.doSayHello("world");
        System.out.println("result: " + result);

        //此处返回了Double类型
        List<Float> floats = application.getFloats();
        System.out.println("floats = " + floats);
        Float aFloat = floats.get(0);
    }

    public String doSayHello(String name) {
        return demoService.sayHello(name);
    }

    public List<Float> getFloats() {
        return demoService.getFloats();
    }
}

3. 预期返回Float类型实际Double

[natsumm]

经验证，dubbo 3.0.0~3.1.5均存在此问题

[mytang0]

Yes, the problem is caused by serialization of float by hessian.

[natsumm]

However, when I used other serialization protocols(like kryo and sft), it still returned Double type except nativejava.

[mytang0]

However, when I used other serialization protocols(like kryo and sft), it still returned Double type except nativejava.

Thank you for your feedback. Let's wait for the fix.

[natsumm]

Thank you for your feedback. Let's wait for the fix.

Ok, thank you for the reply.

[KamToHung]

I try to use fastjson2, kryo and sft that it return float. I think the problem is hessian serialization. org.apache.dubbo.rpc.protocol.dubbo.DecodeableRpcResult#handleValue http://hessian.caucho.com/doc/hessian-serialization.html

dubbo version: 3.1.5

        <dependency>
            <groupId>org.apache.dubbo.extensions</groupId>
            <artifactId>dubbo-serialization-kryo</artifactId>
            <version>1.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.dubbo.extensions</groupId>
            <artifactId>dubbo-serialization-fst</artifactId>
            <version>1.0.0</version>
        </dependency>

[natsumm]

我目前是这么处理的 dubbo.version = 3.1.5

1 application.yml

dubbo:
  protocols:
    dubbo:
      name: dubbo
      serialization: fst

2 pom.xml

<dependency>
    <groupId>org.apache.dubbo</groupId>
    <artifactId>dubbo-serialization-fst</artifactId>
</dependency>

[natsumm]

我目前是这么处理的 dubbo.version = 3.1.5

1 application.yml

dubbo:
  protocols:
    dubbo:
      name: dubbo
      serialization: fst

2 pom.xml

<dependency>
    <groupId>org.apache.dubbo</groupId>
    <artifactId>dubbo-serialization-fst</artifactId>
</dependency>

使用fst插件的版本为 2.7.22