SpringMVC-Handler-Return Values返回值

Controller method return value

Description

@ResponseBody

The return value is converted through HttpMessageConverters and written to the response. See @ResponseBody.

返回值通过HttpMessageConverters转换并写入响应。 请参阅@ResponseBody。

处理器功能处理方法的返回值作为响应体（通过HttpMessageConverter进行类型转换）；

作用： 该注解用于将Controller的方法返回的对象，通过适当的HttpMessageConverter转换为指定格式后，写入到Response对象的body数据区。

使用时机：返回的数据不是html标签的页面，而是其他某种格式的数据时（如json、xml等）使用；

HttpEntity<B>, ResponseEntity<B>

The return value specifies the full response including HTTP headers and body be converted through HttpMessageConverters and written to the response. See ResponseEntity.

返回值指定完整响应，包括HTTP标头和正文通过HttpMessageConverters转换并写入响应。 请参阅ResponseEntity。

HttpHeaders

For returning a response with headers and no body.

为了返回一个响应头和没有正文。

String

A view name to be resolved with ViewResolver's and used together with the implicit model — determined through command objects and @ModelAttribute methods. The handler method may also programmatically enrich the model by declaring a Model argument (see above).

一个视图名称，用ViewResolver解决，并与隐式模型一起使用 - 通过命令对象和@ModelAttribute方法确定。 处理程序方法也可以通过声明一个Model参数来以编程方式丰富模型（参见上文）。

View

A View instance to use for rendering together with the implicit model — determined through command objects and @ModelAttribute methods. The handler method may also programmatically enrich the model by declaring a Model argument (see above).

用于与隐式模型一起渲染的View实例 - 通过命令对象和@ModelAttribute方法确定。 处理程序方法也可以通过声明一个Model参数来以编程方式丰富模型（参见上文）。

java.util.Map, org.springframework.ui.Model

Attributes to be added to the implicit model with the view name implicitly determined through a RequestToViewNameTranslator.

要通过RequestToViewNameTranslator隐式确定的视图名称添加到隐式模型的属性。

@ModelAttribute

An attribute to be added to the model with the view name implicitly determined through a RequestToViewNameTranslator.

Note that @ModelAttribute is optional. See "Any other return value" further below in this table.

要通过RequestToViewNameTranslator隐式确定的视图名称添加到模型的属性。

请注意@ModelAttribute是可选的。 请参阅本表下面的“任何其他返回值”。

ModelAndView object

The view and model attributes to use, and optionally a response status.

要使用的视图和模型属性，以及可选的响应状态。

void

A method with a void return type (or null return value) is considered to have fully handled the response if it also has a ServletResponse, or an OutputStream argument, or an @ResponseStatus annotation. The same is true also if the controller has made a positive ETag or lastModified timestamp check (see @Controller caching for details).

If none of the above is true, a void return type may also indicate "no response body" for REST controllers, or default view name selection for HTML controllers.

具有void返回类型（或返回值为null）的方法如果还有ServletResponse，OutputStream参数或@ResponseStatus注释，则认为它已完全处理响应。 如果控制器进行了积极的ETag或lastModified时间戳检查（请参阅@Controller缓存了解详细信息），情况也是如此。

如果以上都不是这样，那么void返回类型也可能指示REST控制器的“无响应主体”，或HTML控制器的默认视图名称选择。

DeferredResult<V>

Produce any of the above return values asynchronously from any thread — e.g. possibly as a result of some event or callback. See Async Requests and DeferredResult.

从任何线程异步生成任何上述返回值 - 例如 可能是由于某些事件或回调。 请参阅异步请求和延期结果。

Callable<V>

Produce any of the above return values asynchronously in a Spring MVC managed thread. See Async Requests and Callable.

ListenableFuture<V>, java.util.concurrent.CompletionStage<V>, java.util.concurrent.CompletableFuture<V>

Alternative to DeferredResult as a convenience for example when an underlying service returns one of those.

在Spring MVC托管线程中异步生成上述任何返回值。 请参阅异步请求和可调用

ResponseBodyEmitter, SseEmitter

Emit a stream of objects asynchronously to be written to the response with HttpMessageConverter's; also supported as the body of a ResponseEntity. See Async Requests and HTTP Streaming.

用HttpMessageConverter's异步发出一个对象流写入响应; 也支持作为ResponseEntity的主体。 请参阅异步请求和HTTP流。

StreamingResponseBody

Write to the response OutputStream asynchronously; also supported as the body of a ResponseEntity. See Async Requests and HTTP Streaming.

异步写入响应的OutputStream; 也支持作为ResponseEntity的主体。请参阅异步请求和HTTP流程。

Reactive types — Reactor, RxJava, or others via ReactiveAdapterRegistry

Alternative to `DeferredResult with multi-value streams (e.g. Flux, Observable) collected to a List.

For streaming scenarios — e.g. text/event-stream, application/json+stream —  SseEmitter and ResponseBodyEmitter are used instead, where ServletOutputStream blocking I/O is performed on a Spring MVC managed thread and back pressure applied against the completion of each write.

See Async Requests and Reactive types.

具有多值流的DeferredResult（例如Flux，Observable）的替代方法被收集到列表中。

对于流式场景 - 例如 text / event-stream，application / json + stream - 使用SseEmitter和ResponseBodyEmitter，而在Spring MVC托管线程上执行ServletOutputStream阻塞I / O，并在每次写入完成时施加背压。

请参阅异步请求和反应类型。

Any other return value

If a return value is not matched to any of the above, by default it is treated as a view name, if it is String or void (default view name selection via RequestToViewNameTranslator applies); or as a model attribute to be added to the model, unless it is a simple type, as determined by BeanUtils#isSimpleProperty in which case it remains unresolved.

如果返回值与以上任何一个不匹配，默认情况下它被视为视图名称，如果它是String或void（通过RequestToViewNameTranslator应用的默认视图名称选择）; 或者作为要添加到模型的模型属性，除非它是一个简单的类型，由BeanUtils＃isSimpleProperty确定，在这种情况下，它仍然未解决。