How to best get a byte array from a ClientResponse from Spring WebClient?
ClientResponse.bodyToMono()
in the end uses some org.springframework.core.codec.Decoder
which claims to support the specified class.
So we should check the class hierarchy of the Decoder
, in particular where and how the decodeToMono()
method is implemented.
There is a StringDecoder
which supports decoding to String
, a bunch of Jackson-related decoders (used in your DTO example under the hood), and there is also a ResourceDecoder
which is of particular interest.
ResourceDecoder
supports org.springframework.core.io.InputStreamResource
and org.springframework.core.io.ByteArrayResource
. ByteArrayResource
is essentially a wrapper around byte[]
, so the following code will provide an access to the response body as a byte array:
Mono<byte[]> mono = client.get()
...
.exchange()
.flatMap(response -> response.bodyToMono(ByteArrayResource.class))
.map(ByteArrayResource::getByteArray);
Oleg Estekhin's answer gives the OP what he asked for, but it's loading the entire response content in the memory, which is an issue for large responses. To get a chunk of bytes at a time instead, we can do the following:
client.get()
.uri("uri")
.exchange()
.flatMapMany { it.body(BodyExtractors.toDataBuffers()) }
The size of these buffers would be 8192 kb by default; see this answer for changing that if needed.
Note that attempting to do dataBuffer.asByteBuffer().array()
thrwos an exception if the ByteBuffer
is not backed by an array.