org.springframework.web.servlet.mvc.method.annotation

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, a ResponseBodyEmitter can be used to send multiple objects where each object is written with a compatible HttpMessageConverter.

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

Constructor Summary

Constructors

Constructor and Description
ResponseBodyEmitter() Create a new ResponseBodyEmitter instance.
ResponseBodyEmitter(Long timeout) Create a ResponseBodyEmitter with a custom timeout value.

Method Summary

Modifier and Type	Method and Description
void	complete() Complete request processing.
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	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) Write the given object to the response also using a MediaType hint.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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 - timeout value in milliseconds

Method Detail

getTimeout

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.

Parameters:

object - the object to write

Throws:

IOException - raised when an I/O error occurs

IllegalStateException - wraps any other errors

send

public void send(Object object,
                 MediaType mediaType)
          throws IOException

Write the given object to the response also using a MediaType hint.

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.

Parameters:

object - the object to write

mediaType - a MediaType hint for selecting an HttpMessageConverter

Throws:

IOException - raised when an I/O error occurs

IllegalStateException - wraps any other errors

complete

public void complete()

Complete request processing.

A dispatch is made into the app server where Spring MVC completes asynchronous request processing.

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.

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.

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 a ResponseBodyEmitter instance is no longer usable.