How to get raw binary data from a POST request processed by Spring?

Question

I need to write an application which would be able to process binary data sent by CUrl, such as:

curl localhost:8080/data --data-binary @ZYSF15A46K1.txt

I've created a POST processing method as follows:

@RequestMapping(method = RequestMethod.POST, value = "/data")
    public void acceptData(HttpEntity<byte[]> requestEntity) throws Exception {
        process(requestEntity.getBody());
    }

However it doesn't seem to be returning raw binary data. I've tried sending a GZip file and after going through Spring it is now longer decompressible, which leads me to believe I'm either getting too much data or too little data.

How do I solve this issue and get raw binary data?

Sadfaced

Try to use HttpServletDequest as the input parameter of your controller and read raw data from it's InputStream. – Meagre

@GeminiKeith tried that as well, it's always returning an empty object for some reason. – Sadfaced

have you ever set the character encoding? You can check the Content-Length to make sure you get the right request. If Content-Length valid, you can read it from InputStream with specific length. If not please check your request. – Meagre

@GeminiKeith Thank you! I looked a bit more into HttpServletRequest and the issue was solved (see my answer). – Sadfaced

Answer 1

It's as easy as declaring an InputStream in your controller method's parameters:

@RequestMapping(method = RequestMethod.POST, value = "/data")
public void acceptData(InputStream dataStream) throws Exception {
    processText(dataStream);
}

You shouldn't need to disable HiddenHttpMethodFilter, if you do it's probably that your request is wrong in some way. See https://github.com/spring-projects/spring-boot/issues/5676.

Hokusai

"wrong in some way" = check that Content-Type header is set in request and that it is not multipart/form-data or application/x-www-form-url-encoded – Yonit

what annotation shall I use to get binary data from postman to spring boot? – Europe

it depends on how you send it with postman. See this learning.getpostman.com/docs/postman/sending-api-requests/…. If you send "raw" data, you can use the declaration above as-is. – Hokusai

Answer 2

I was able to resolve this using the following code:

@Bean
public FilterRegistrationBean registration(HiddenHttpMethodFilter filter) {
    FilterRegistrationBean registration = new FilterRegistrationBean(filter);
    registration.setEnabled(false);
    return registration;
}

@RequestMapping(method = RequestMethod.POST, value = "/data")
public void acceptData(HttpServletRequest requestEntity) throws Exception {
    byte[] processedText = IOUtils.toByteArray(requestEntity.getInputStream());
    processText(processedText);
}

Spring does pre-processing by default, which causes the HttpServletRequest to be empty by the time it reaches the RequestMapping. Adding the FilterRegistrationBean Bean solves that issue.

Sadfaced

Yes, I've forgot that. Input Stream default can only be read once. – Meagre

My hunch is that funky HiddenHttpMethodFilter disable is to turn off auto multipart filtering: https://mcmap.net/q/361950/-springboot-large-streaming-file-upload-using-apache-commons-fileupload – Trifocal