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 java.lang.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
    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class and 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 and Description
      ResponseBodyEmitter()
      Create a new ResponseBodyEmitter instance.
      ResponseBodyEmitter(java.lang.Long timeout)
      Create a ResponseBodyEmitter with a custom timeout value.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method and 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(java.lang.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.
      java.lang.Long getTimeout()
      Return the configured timeout value, if any.
      void onCompletion(java.lang.Runnable callback)
      Register code to invoke when the async request completes.
      void onError(java.util.function.Consumer<java.lang.Throwable> callback)
      Register code to invoke for an error during async request processing.
      void onTimeout(java.lang.Runnable callback)
      Register code to invoke when the async request times out.
      void send(java.lang.Object object)
      Write the given object to the response.
      void send(java.lang.Object object, MediaType mediaType)
      Overloaded variant of send(Object) that also accepts a MediaType hint for how to serialize the given Object.
      java.lang.String toString() 
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Constructor Detail

      • ResponseBodyEmitter

        public ResponseBodyEmitter()
        Create a new ResponseBodyEmitter instance.
      • ResponseBodyEmitter

        public ResponseBodyEmitter(java.lang.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

        @Nullable
        public java.lang.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(java.lang.Object object)
                  throws java.io.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:
        java.io.IOException - raised when an I/O error occurs
        java.lang.IllegalStateException - wraps any other errors
      • send

        public void send(java.lang.Object object,
                         @Nullable
                         MediaType mediaType)
                  throws java.io.IOException
        Overloaded variant of send(Object) that also accepts a MediaType hint for how to serialize the given Object.
        Parameters:
        object - the object to write
        mediaType - a MediaType hint for selecting an HttpMessageConverter
        Throws:
        java.io.IOException - raised when an I/O error occurs
        java.lang.IllegalStateException - 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(java.lang.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(java.lang.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(java.util.function.Consumer<java.lang.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(java.lang.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.
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object