How to send byte[] array in retrofit

How do you send byte[] array in retrofit call. I just need to send over byte[]. I get this exception when I have been trying to send a retrofit call.

retrofit.RetrofitError: retrofit.converter.ConversionException: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException:  Expected a string but was BEGIN_OBJECT at line 1 column 2

What is the way I can make the call using retrofit.

I was simply passing byte array as a ByteMessage encapsulated in the object class.

public class ByteMessage {
    
    private byte[] byteArray;
    
    byte[] getByteArray() {
        return byteArray;
    }

    setByteArray(byte[] bytes){
        byteArray = bytes;
    }

}

@POST("/send")
sendBytes(ByteMesssage msg);

Server side:

sendBytes(ByteMessage msg) {
    byte[] byteArray = msg.getByte();
    ...doSomething... 
}

I could not find resources on the stack overflow or googling for a proper solution passing byte arrays through retrofit call.

Can anyone please help with this.

Thanks Dhiren

Answer

For this purpose you can use TypedByteArray

Your Retrofit service will look like this:

@POST("/send")
void upload(@Body TypedInput bytes, Callback<String> cb);

Your client code:

    byte[] byteArray = ...
    TypedInput typedBytes = new TypedByteArray("application/octet-stream",  byteArray);
    remoteService.upload(typedBytes, new Callback<String>() {
        @Override
        public void success(String s, Response response) {
            //Success Handling
        }

        @Override
        public void failure(RetrofitError retrofitError) {
            //Error Handling
        }
    }); 

“application/octet-stream” – instead this MIME-TYPE, you maybe want to use your data format type. Detail information you can find here: http://www.freeformatter.com/mime-types-list.html

And Spring MVC controller (if you need one):

@RequestMapping(value = "/send", method = RequestMethod.POST)
public ResponseEntity<String> receive(@RequestBody byte[] data) {
    //handle data
    return new ResponseEntity<>(HttpStatus.CREATED);
}