org.springframework.core.ResolvableTypeProvider Java Examples

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Example #1
Source File: MultipartHttpMessageWriter.java    From spring-analysis-note with MIT License 4 votes vote down vote up
@SuppressWarnings("unchecked")
private <T> Flux<DataBuffer> encodePart(byte[] boundary, String name, T value, DataBufferFactory bufferFactory) {
	MultipartHttpOutputMessage outputMessage = new MultipartHttpOutputMessage(bufferFactory, getCharset());
	HttpHeaders outputHeaders = outputMessage.getHeaders();

	T body;
	ResolvableType resolvableType = null;
	if (value instanceof HttpEntity) {
		HttpEntity<T> httpEntity = (HttpEntity<T>) value;
		outputHeaders.putAll(httpEntity.getHeaders());
		body = httpEntity.getBody();
		Assert.state(body != null, "MultipartHttpMessageWriter only supports HttpEntity with body");
		if (httpEntity instanceof ResolvableTypeProvider) {
			resolvableType = ((ResolvableTypeProvider) httpEntity).getResolvableType();
		}
	}
	else {
		body = value;
	}
	if (resolvableType == null) {
		resolvableType = ResolvableType.forClass(body.getClass());
	}

	if (!outputHeaders.containsKey(HttpHeaders.CONTENT_DISPOSITION)) {
		if (body instanceof Resource) {
			outputHeaders.setContentDispositionFormData(name, ((Resource) body).getFilename());
		}
		else if (resolvableType.resolve() == Resource.class) {
			body = (T) Mono.from((Publisher<?>) body).doOnNext(o -> outputHeaders
					.setContentDispositionFormData(name, ((Resource) o).getFilename()));
		}
		else {
			outputHeaders.setContentDispositionFormData(name, null);
		}
	}

	MediaType contentType = outputHeaders.getContentType();

	final ResolvableType finalBodyType = resolvableType;
	Optional<HttpMessageWriter<?>> writer = this.partWriters.stream()
			.filter(partWriter -> partWriter.canWrite(finalBodyType, contentType))
			.findFirst();

	if (!writer.isPresent()) {
		return Flux.error(new CodecException("No suitable writer found for part: " + name));
	}

	Publisher<T> bodyPublisher =
			body instanceof Publisher ? (Publisher<T>) body : Mono.just(body);

	// The writer will call MultipartHttpOutputMessage#write which doesn't actually write
	// but only stores the body Flux and returns Mono.empty().

	Mono<Void> partContentReady = ((HttpMessageWriter<T>) writer.get())
			.write(bodyPublisher, resolvableType, contentType, outputMessage, DEFAULT_HINTS);

	// After partContentReady, we can access the part content from MultipartHttpOutputMessage
	// and use it for writing to the actual request body

	Flux<DataBuffer> partContent = partContentReady.thenMany(Flux.defer(outputMessage::getBody));

	return Flux.concat(
			generateBoundaryLine(boundary, bufferFactory),
			partContent,
			generateNewLine(bufferFactory));
}