Method Arguments

下表显示所支持的控制器方法参数。

The following table shows the supported controller method arguments.

在需要阻塞 I/O（例如读取请求主体）才能解析的参数上支持响应类型（Reactor、RxJava、or other）。这会在描述列中进行标记。在不需要阻塞的参数上不预期有响应类型。

Reactive types (Reactor, RxJava, or other) are supported on arguments that require blocking I/O (for example, reading the request body) to be resolved. This is marked in the Description column. Reactive types are not expected on arguments that do not require blocking.

JDK 1.8 的 java.util.Optional 支持作为方法参数，并与具有 required 属性的注释（例如，@RequestParam、@RequestHeader 和其他）结合使用，并且等效于 required=false。

JDK 1.8’s java.util.Optional is supported as a method argument in combination with annotations that have a required attribute (for example, @RequestParam, @RequestHeader, and others) and is equivalent to required=false.

Controller method argument Description

Controller method argument	Description
`ServerWebExchange`	Access to the full `ServerWebExchange` — container for the HTTP request and response, request and session attributes, `checkNotModified` methods, and others.
`ServerHttpRequest`, `ServerHttpResponse`	Access to the HTTP request or response.
`WebSession`	Access to the session. This does not force the start of a new session unless attributes are added. Supports reactive types.
`java.security.Principal`	The currently authenticated user — possibly a specific `Principal` implementation class if known. Supports reactive types.
`org.springframework.http.HttpMethod`	The HTTP method of the request.
`java.util.Locale`	The current request locale, determined by the most specific `LocaleResolver` available — in effect, the configured `LocaleResolver`/`LocaleContextResolver`.
`java.util.TimeZone` + `java.time.ZoneId`	The time zone associated with the current request, as determined by a `LocaleContextResolver`.
`@PathVariable`	For access to URI template variables. See URI Patterns.
`@MatrixVariable`	For access to name-value pairs in URI path segments. See Matrix Variables.
`@RequestParam`	For access to query parameters. Parameter values are converted to the declared method argument type. See `@RequestParam`. Note that use of `@RequestParam` is optional — for example, to set its attributes. See “Any other argument” later in this table.
`@RequestHeader`	For access to request headers. Header values are converted to the declared method argument type. See `@RequestHeader`.
`@CookieValue`	For access to cookies. Cookie values are converted to the declared method argument type. See `@CookieValue`.
`@RequestBody`	For access to the HTTP request body. Body content is converted to the declared method argument type by using `HttpMessageReader` instances. Supports reactive types. See `@RequestBody`.
`HttpEntity<B>`	For access to request headers and body. The body is converted with `HttpMessageReader` instances. Supports reactive types. See `HttpEntity`.
`@RequestPart`	For access to a part in a `multipart/form-data` request. Supports reactive types. See Multipart Content and Multipart Data.
`java.util.Map` or `org.springframework.ui.Model`	For access to the model that is used in HTML controllers and is exposed to templates as part of view rendering.
`@ModelAttribute`	For access to an existing attribute in the model (instantiated if not present) with data binding and validation applied. See `@ModelAttribute` as well as `Model` and `DataBinder`. Note that use of `@ModelAttribute` is optional — for example, to set its attributes. See “Any other argument” later in this table.
`Errors` or `BindingResult`	For access to errors from validation and data binding for a command object, i.e. a `@ModelAttribute` argument. An `Errors` or `BindingResult` argument must be declared immediately after the validated method argument.
`SessionStatus` + class-level `@SessionAttributes`	For marking form processing complete, which triggers cleanup of session attributes declared through a class-level `@SessionAttributes` annotation. See `@SessionAttributes` for more details.
`UriComponentsBuilder`	For preparing a URL relative to the current request’s host, port, scheme, and context path. See URI Links.
`@SessionAttribute`	For access to any session attribute — in contrast to model attributes stored in the session as a result of a class-level `@SessionAttributes` declaration. See `@SessionAttribute` for more details.
`@RequestAttribute`	For access to request attributes. See `@RequestAttribute` for more details.
Any other argument	If a method argument is not matched to any of the above, it is, by default, resolved as a `@RequestParam` if it is a simple type, as determined by BeanUtils#isSimpleProperty, or as a `@ModelAttribute`, otherwise.

ServerWebExchange

Access to the full ServerWebExchange — container for the HTTP request and response, request and session attributes, checkNotModified methods, and others.

ServerHttpRequest, ServerHttpResponse

Access to the HTTP request or response.

WebSession

Access to the session. This does not force the start of a new session unless attributes are added. Supports reactive types.

java.security.Principal

The currently authenticated user — possibly a specific Principal implementation class if known. Supports reactive types.

org.springframework.http.HttpMethod

The HTTP method of the request.

java.util.Locale

The current request locale, determined by the most specific LocaleResolver available — in effect, the configured LocaleResolver/LocaleContextResolver.

java.util.TimeZone + java.time.ZoneId

The time zone associated with the current request, as determined by a LocaleContextResolver.

@PathVariable

For access to URI template variables. See URI Patterns.

@MatrixVariable

For access to name-value pairs in URI path segments. See Matrix Variables.

@RequestParam

For access to query parameters. Parameter values are converted to the declared method argument type. See @RequestParam.

Note that use of @RequestParam is optional — for example, to set its attributes. See “Any other argument” later in this table.

@RequestHeader

For access to request headers. Header values are converted to the declared method argument type. See @RequestHeader.

@CookieValue

For access to cookies. Cookie values are converted to the declared method argument type. See @CookieValue.

@RequestBody

For access to the HTTP request body. Body content is converted to the declared method argument type by using HttpMessageReader instances. Supports reactive types. See @RequestBody.

HttpEntity<B>

For access to request headers and body. The body is converted with HttpMessageReader instances. Supports reactive types. See HttpEntity.

@RequestPart

For access to a part in a multipart/form-data request. Supports reactive types. See Multipart Content and Multipart Data.

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

For access to the model that is used in HTML controllers and is exposed to templates as part of view rendering.

@ModelAttribute

For access to an existing attribute in the model (instantiated if not present) with data binding and validation applied. See @ModelAttribute as well as Model and DataBinder.

Note that use of @ModelAttribute is optional — for example, to set its attributes. See “Any other argument” later in this table.

Errors or BindingResult

For access to errors from validation and data binding for a command object, i.e. a @ModelAttribute argument. An Errors or BindingResult argument must be declared immediately after the validated method argument.

SessionStatus + class-level @SessionAttributes

For marking form processing complete, which triggers cleanup of session attributes declared through a class-level @SessionAttributes annotation. See @SessionAttributes for more details.

UriComponentsBuilder

For preparing a URL relative to the current request’s host, port, scheme, and context path. See URI Links.

@SessionAttribute

For access to any session attribute — in contrast to model attributes stored in the session as a result of a class-level @SessionAttributes declaration. See @SessionAttribute for more details.

@RequestAttribute

For access to request attributes. See @RequestAttribute for more details.

Any other argument

If a method argument is not matched to any of the above, it is, by default, resolved as a @RequestParam if it is a simple type, as determined by BeanUtils#isSimpleProperty, or as a @ModelAttribute, otherwise.