如何在 Micronaut 中获取反应流?

How to get reactive streams in Micronaut?

在SpringBoot中,对于Webflux项目,我们通过在HTTP请求中发送一个header——“Accept:application/stream+json”来请求数据流。

如果我们发送“接受:application/json”,我们会得到一个有效的 Json。

然而,在 Micronaut 中,如果我发送“接受:application/stream+json”,它会抛出一个错误。

{
    "message": "Specified Accept Types [application/x-json-stream] not supported. Supported types: [application/json]",
    "_links": {
        "self": {
            "href": "/carts/reactive",
            "templated": false
        }
    }
}

Micronaut 中的“接受:application/stream+json”等价于什么?

What is the equivalent of "Accept: application/stream+json" in Micronaut?

正如评论中已经提到的,它是 application/x-json-stream。 (遗憾的是,没有人为流式传输的内容类型制定标准 json,至少现在还没有。)

The question here is to how the client can control the response type - Json/stream. You are using produces = {MediaType.APPLICATION_JSON_STREAM, which means the return type is always stream. In spring boot, we can use Accept header to control what response type we want. I was expecting the same behaviour from Micronaut.

Micronaut 也可以做到这一点 - 你可以将多个值传递给 produces 参数,它会 return 相应地流式传输或标准 JSON:

@Get(value = "/", produces = {MediaType.APPLICATION_JSON_STREAM, MediaType.APPLICATION_JSON})
public Flux<Foo> getFoos() {
    return Flux.range(1, 3).map(i -> new Foo("Number " + i));
}

@Value
class Foo {
    private String content;
}

然后我们可以使用 application/x-json-stream 查询端点以检索 JSON 流:

 > curl localhost:8080 -H "Accept: application/x-json-stream"
{"content":"Number 1"}{"content":"Number 2"}{"content":"Number 3"}

...或普通 application/json 检索标准 JSON 数组:

 > curl localhost:8080 -H "Accept: application/json"
[{"content":"Number 1"},{"content":"Number 2"},{"content":"Number 3"}]

如果您希望对每种接受类型的行为进行更多自定义控制 header,那么您可以完全定义单独的控制器方法:

@Get(value = "/", produces = MediaType.APPLICATION_JSON_STREAM)
public Flux<Foo> getFoosStream() {
    return Flux.range(1, 3).map(i -> new Foo("Reactive " + i));
}

@Get(value = "/", produces = MediaType.APPLICATION_JSON)
public List<Foo> getFoosStandard() {
    return List.of(new Foo("Standard 1"), new Foo("Standard 2"), new Foo("Standard 3"));
}

...并且根据您发送的 header,将执行不同的方法(如上所述,您将能够看到标准 curl 命令的区别。)