Calling a Spring Boot 2 REST service with multipart/form-data with Postman results in a EOFException

Question

While working on a personal project on Spring Boot, I have to develop a web service that accepts a file and some metadata, and I have decided to test with a Postman client.

Versions I am using:

Postman version: Postman for Mac Version 7.8.0 OS X 18.7.0 / x64
Java version: 1.8.0_212
Spring boot version: 2.1.1.RELEASE

As metadata will potentially be quite structured, I have decided to use the multipart/form-data content type, consisting in two parts:

a "file" part containing the file
a "body" part containing the json with the metadata

I've configured the call in Postman like this

Now, Spring boot configuration. First of all, I've added the following lines to application.properties:

## MULTIPART (MultipartProperties)
# Enable multipart uploads
spring.servlet.multipart.enabled=true
# Threshold after which files are written to disk.
spring.servlet.multipart.file-size-threshold=2KB
# Max file size.
spring.servlet.multipart.max-file-size=20MB
# Max Request Size
spring.servlet.multipart.max-request-size=25MB

I've then created my controller with the endpoint

@PostMapping(Paths.Registrations.BASE)
@ResponseBody
public PostRegistrationResponseDto postRegistration(@RequestParam("file") MultipartFile file, @RequestParam("body") PostRegistrationRequestDto req) {
    PostRegistrationResponseDto resp = new PostRegistrationResponseDto();
    resp.setId(new Random().nextLong());
    resp.setFileName(req.getFileName());
    resp.setRegistrationTime(LocalDateTime.now());

    return resp;
}

Unfortunately, the call does not even arrive to Spring: I receive a HTTP 500 error with this body

<!doctype html>
<html lang="en">

<head>
    <title>HTTP Status 500 – Internal Server Error</title>
    <style type="text/css">
        ...
    </style>
</head>

<body>
    <h1>HTTP Status 500 – Internal Server Error</h1>
</body>

</html>

In my server log I get no exception, but when I set the debugger to block on exceptions I saw that tomcat launches an EOF exception with this stack trace

java.io.EOFException
at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.fillReadBuffer(NioEndpoint.java:1208)
at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.read(NioEndpoint.java:1142)
at org.apache.coyote.http11.Http11InputBuffer.fill(Http11InputBuffer.java:729)
at org.apache.coyote.http11.Http11InputBuffer.parseRequestLine(Http11InputBuffer.java:352)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:294)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:791)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)

I admit I do not even know where to start from... can someone give me some hints of what I'm doing wrong?

Thanks :)

score 0 · Answer 1 · answered Oct 14 '19 at 08:20

In the end, what I discovered is that Tomcat throws a lot of exceptions, not always meaningful.

The problem I had was not related to that exception, but to the fact that Spring doesn't automatically map the String part to the Dto.

To make everything work, I had to write this component:

package it.aegidea.proofy.api.converters;

import com.fasterxml.jackson.databind.ObjectMapper;
import it.aegidea.proofy.api.dtos.proofyapi.PostRegistrationRequestDto;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.convert.converter.Converter;
import org.springframework.stereotype.Component;

import java.io.IOException;

@Component
public class PostRegistrationRequestDtoConverter implements Converter<String, PostRegistrationRequestDto> {

    private final ObjectMapper objectMapper;

    @Autowired
    public PostRegistrationRequestDtoConverter(final ObjectMapper objectMapper) {
        this.objectMapper = objectMapper;
    }

    @Override
    public PostRegistrationRequestDto convert(String source) {
        try {
            return objectMapper.readValue(source, PostRegistrationRequestDto.class);
        } catch (IOException e) {
            return null;
        }
    }

}

This way, Spring understood how to map the string to a PostRegistrationRequestDto and could successfully map the request to the types on the endpoint.

Calling a Spring Boot 2 REST service with multipart/form-data with Postman results in a EOFException

1 Answers1