Class ResponseBodyEmitter
- java.lang.Object
- org.springframework.web.servlet.mvc.method.annotation.ResponseBodyEmitter
- Direct Known Subclasses:
SseEmitter
public class ResponseBodyEmitter extends Object
A controller method return value type for asynchronous request processing where one or more objects are written to the response.While
DeferredResult
is used to produce a single result, aResponseBodyEmitter
can be used to send multiple objects where each object is written with a compatibleHttpMessageConverter
.Supported as a return type on its own as well as within a
ResponseEntity
.@RequestMapping(value="/stream", method=RequestMethod.GET) public ResponseBodyEmitter handle() { ResponseBodyEmitter emitter = new ResponseBodyEmitter(); // Pass the emitter to another component... return emitter; } // in another thread emitter.send(foo1); // and again emitter.send(foo2); // and done emitter.complete();
- Since:
- 4.2
- Author:
- Rossen Stoyanchev, Juergen Hoeller
Nested Class Summary
Nested Classes Modifier and Type Class Description static class
ResponseBodyEmitter.DataWithMediaType
A simple holder of data to be written along with a MediaType hint for selecting a message converter to write with.
Constructor Summary
Constructors Constructor Description ResponseBodyEmitter()
Create a new ResponseBodyEmitter instance.ResponseBodyEmitter(Long timeout)
Create a ResponseBodyEmitter with a custom timeout value.
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
complete()
Complete request processing by performing a dispatch into the servlet container, where Spring MVC is invoked once more, and completes the request processing lifecycle.void
completeWithError(Throwable ex)
Complete request processing with an error.protected void
extendResponse(ServerHttpResponse outputMessage)
Invoked after the response is updated with the status code and headers, if the ResponseBodyEmitter is wrapped in a ResponseEntity, but before the response is committed, i.e.Long
getTimeout()
Return the configured timeout value, if any.void
onCompletion(Runnable callback)
Register code to invoke when the async request completes.void
onError(Consumer<Throwable> callback)
Register code to invoke for an error during async request processing.void
onTimeout(Runnable callback)
Register code to invoke when the async request times out.void
send(Object object)
Write the given object to the response.void
send(Object object, MediaType mediaType)
Overloaded variant ofsend(Object)
that also accepts a MediaType hint for how to serialize the given Object.String
toString()
Constructor Detail
ResponseBodyEmitter
public ResponseBodyEmitter()
Create a new ResponseBodyEmitter instance.
ResponseBodyEmitter
public ResponseBodyEmitter(Long timeout)
Create a ResponseBodyEmitter with a custom timeout value.By default not set in which case the default configured in the MVC Java Config or the MVC namespace is used, or if that's not set, then the timeout depends on the default of the underlying server.
- Parameters:
timeout
- the timeout value in milliseconds
Method Detail
getTimeout
@Nullable public Long getTimeout()
Return the configured timeout value, if any.
extendResponse
protected void extendResponse(ServerHttpResponse outputMessage)
Invoked after the response is updated with the status code and headers, if the ResponseBodyEmitter is wrapped in a ResponseEntity, but before the response is committed, i.e. before the response body has been written to.The default implementation is empty.
send
public void send(Object object) throws IOException
Write the given object to the response.If any exception occurs a dispatch is made back to the app server where Spring MVC will pass the exception through its exception handling mechanism.
Note: if the send fails with an IOException, you do not need to call
completeWithError(Throwable)
in order to clean up. Instead the Servlet container creates a notification that results in a dispatch where Spring MVC invokes exception resolvers and completes processing.- Parameters:
object
- the object to write- Throws:
IOException
- raised when an I/O error occursIllegalStateException
- wraps any other errors
send
public void send(Object object, @Nullable MediaType mediaType) throws IOException
Overloaded variant ofsend(Object)
that also accepts a MediaType hint for how to serialize the given Object.- Parameters:
object
- the object to writemediaType
- a MediaType hint for selecting an HttpMessageConverter- Throws:
IOException
- raised when an I/O error occursIllegalStateException
- wraps any other errors
complete
public void complete()
Complete request processing by performing a dispatch into the servlet container, where Spring MVC is invoked once more, and completes the request processing lifecycle.Note: this method should be called by the application to complete request processing. It should not be used after container related events such as an error while
sending
.
completeWithError
public void completeWithError(Throwable ex)
Complete request processing with an error.A dispatch is made into the app server where Spring MVC will pass the exception through its exception handling mechanism. Note however that at this stage of request processing, the response is committed and the response status can no longer be changed.
Note: this method should be called by the application to complete request processing with an error. It should not be used after container related events such as an error while
sending
.
onTimeout
public void onTimeout(Runnable callback)
Register code to invoke when the async request times out. This method is called from a container thread when an async request times out.
onError
public void onError(Consumer<Throwable> callback)
Register code to invoke for an error during async request processing. This method is called from a container thread when an error occurred while processing an async request.- Since:
- 5.0
onCompletion
public void onCompletion(Runnable callback)
Register code to invoke when the async request completes. This method is called from a container thread when an async request completed for any reason including timeout and network error. This method is useful for detecting that aResponseBodyEmitter
instance is no longer usable.