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Spring Boot: How to resolve Content-Type when incorrectly received from server

I have the following class in Java. I'm expecting it to issue a GET request to the url, get back a JSON payload, and transform that payload to List<LocationData>.
package ...
import ...
#Repository
public class ProxiedLocationRepo {
public List<LocationData> findAll() throws Exception {
RestTemplate restTemplate = new RestTemplate();
String url = UriComponentsBuilder
.fromUriString("https://my-host/path")
.queryParams("some", "queryParams")
.toUriString();
ResponseEntity<List<LocationData>> res = restTemplate.exchange(
url,
HttpMethod.GET,
null,
new ParameterizedTypeReference<List<LocationData>>(){});
if (res.getStatusCode() == HttpStatus.ACCEPTED) {
return res.getBody();
} else {
throw new ResponseStatusException(res.getStatusCode(), "Did not receive a 200 response from Server.");
}
}
}
However, I'm getting back this error:
org.springframework.http.InvalidMediaTypeException: Invalid mime type "charset=UTF-8": does not contain '/'
Which is expected, because if I do the same request from curl, and check the headers I get this (notice Content-Type line):
$ curl -sfi 'https://my-host/path?some=queryParams'
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 06 Mar 2019 13:58:58 GMT
Content-Type: charset=UTF-8
Content-Length: 1821
Connection: keep-alive
Vary: Accept-Encoding
Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Frame-Options: SAMEORIGIN
... # perfectly formatted JSON payload here
I know that the Content-Type returned from this server is going to be application/json, but it is not providing it to me.
Is there anyway to inform RestTemplate#exchange of what the Content-Type of the response will be? If not, is there any other methodology I could use to resolve this issue besides getting the owners of the server to set the Content-Type correctly?
EDIT:
I have also tried adding the "Accept" header but got the same results:
$ curl -sfi 'https://my-host/path?some=queryParams' \
-H 'Accept: application/json'

Unfortunately I don't think there's any way to fix this while leveraging the Spring framework. Even if you were to create a custom JsonbHttpMessageConverter that accepts a MIME type of ANY, Spring would still fail to parse the incorrect Content-Type received from the request (because it can't find "/" in the Content-Type string).
So the resolution here was to do use java.net.HttpURLConnection to do the networking instead, and then use com.fasterxml.jackson.databind.ObjectMapper to map from the JSON to a POJO.
It works, but at the cost of no longer being able to leverage any of Spring's HTTP handling, which is likely much much more robust than anything I can implement alone.

How to make $batch POST request using Olingo v2 and Java

I am trying to do a $batch request in Java using OData v2.
An example request from the browser would be something like below between the double quotes.
But how can I make this request programatically? Is there a sample call somewhere? Any help is appreciated.
Request URL: https://someUrl/project/odata/project/FOLDER/$batch
Request Method: POST
Status Code: 202 Accepted
Remote Address: 1.2.3.4:1234
Referrer Policy: no-referrer-when-downgrade
content-encoding: gzip
content-length: 5256
content-type: multipart/mixed; boundary=E828EB257B134AC6F567C8D3B67E666E1
dataserviceversion: 2.0
Accept: multipart/mixed
Accept-Encoding: gzip, deflate, br
Accept-Language: en
Connection: keep-alive
Content-Length: 595
Content-Type: multipart/mixed;boundary=batch_4edb-a2cd-948d
Cookie: project-usercontext=project-language=EN&project-client=100;
--Some cookie content--
DataServiceVersion: 2.0
Host: host.myClient.com:1234
MaxDataServiceVersion: 2.0
Origin: https://host.myClient.com:1234
Referer: https://host.myClient.com:1234/project/index.html
project-cancel-on-close: true
project-contextid-accept: header
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/1.2.3.4 Safari/537.36
x-csrf-token: 8Fd53yy2vuCjnaFKrZNuLg==
--batch_4edb-a2cd-948d
Content-Type: application/http
Content-Transfer-Encoding: binary
GET MyEntityDetailsSet HTTP/1.1
project-contextid-accept: header
Accept: application/json
Accept-Language: en
DataServiceVersion: 2.0
MaxDataServiceVersion: 2.0
project-cancel-on-close: true
> --batch_4edb-a2cd-948d
Content-Type: application/http
Content-Transfer-Encoding: binary
GET MyObjectSet HTTP/1.1
project-contextid-accept: header
Accept: application/json
Accept-Language: en
DataServiceVersion: 2.0
MaxDataServiceVersion: 2.0
project-cancel-on-close: true
--batch_4edb-a2cd-948d--

You can use Olingo V2 as an OData client (although a rather ugly one in my opinion). There is a full tutorial dedicated to this usage on the official Olingo site: How to use Apache Olingo as client library.
Olingo knows to build requests and parse responses, but you need an underlying mechanism to execute the HTTP calls. My recommendation would be to not rely on manually opening HttpURLConnections like in the above example, but to use something like Apache Http Client or some other dedicated library instead (in order to reduce the amount of code you write and also to have access to more advanced concepts like connection polling).
In a nutshell, you must first read and parse the metadata of the service that you want to consume:
// content = read the metadata as an InputStream
Edm dataModel = EntityProvider.readMetadata(content, false);
You can build a batch request via a fluent-style API:
BatchQueryPart part = BatchQueryPart.method("GET")
.uri("/Employees('1')")
.build();
// here you could have a larger list of parts, not just a singleton list
InputStream payload = EntityProvider.writeBatchRequest(
Collections.singletonList(part), "batch_boundary");
Then you have to just execute it using your HTTP request execution mechanism of choice (method = "POST" and body = the payload variable). Afterwards, you can parse the obtained response using Olingo:
// body = the response body received
// contentType = the Content-Type header received
List<BatchSingleResponse> responses =
EntityProvider.parseBatchResponse(responseBody, contentType);
// you can obtain the body for each request from the response list
String partBody = responses.get(0).getBody();
InputStream partStream = new ByteArrayInputStream(partBody.getBytes());
String partType = responses.get(0).getHeader(HttpHeaders.CONTENT_TYPE);
Lastly, using the Edm from the first step you can also parse each individual body based on the type of request that you build. For example you could use the readEntry method to de-serialize a single entity read:
// first we have to find the entity set you used to make the request
EdmEntitySet entitySet = edm.getDefaultEntityContainer()
.getEntitySet("Employees");
ODataEntry entry = EntityProvider.readEntry(partType, entitySet,
partStream, EntityProviderReadProperties.init().build())
Lastly, you can use the entry methods to get e.g. the properties.

Parsing Multipart/mixed in Spring

I want to parse requests like the following in my RestController
POST http://#.#.#.#:#/report HTTP/1.1
User-Agent: Android
Accept: text/html,application/xml,application/json,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Content-Type: multipart/mixed; boundary=%&REPORT_DIVIDER&%
Authorization: Basic ***
Content-Length: 23236
Host: #.#.#.#:#
Connection: Keep-Alive
Accept-Encoding: gzip
--%&REPORT_DIVIDER&%
Content-Type: application/json
{"content-excluded":true}
--%&REPORT_DIVIDER&%
Content-Disposition: attachment; filename="INSTALLATION"
Content-Type: application/octet-stream
609903cf-fcc0-460c-87db-958e031ac156
--%&REPORT_DIVIDER&%--
This message is conform to rfc1341, yet I cannot find a way to parse this in Spring.
Note that the number of files may vary.
I've already tried using CommonsMultipartResolver or StandardServletMultipartResolver, but both only support multipart/form-data (rfc1867).
Is there any way to parse these request in Spring besides writing my own parser?

While it is not a very nice solution, it was the only one I found:
I essentially reimplemented ServletFileUpload with this class and then loaded it into the apache library with this simple subclass of CommonsMultipartResolver

#Path("api")
#PUT
#Consumes("multipart/mixed")
#Produces("multipart/mixed")
public MultiPart twelve( MultiPart multiPart) throws IOException {
List<BodyPart> bodyParts = multiPart.getBodyParts();
BodyPartEntity bpe = (BodyPartEntity) bodyParts.get(1).getEntity();
}
This is for jersey based spring boot project.

How to Read Json data in Restful web services using jax-rs

How to pass json as input to restful web services and how to insert the json data in to database.

Usually you pass JSON payload sending request with POST or PUT method and setting Content-Type header to application/json. Then on the server it converts to an object representation with help of library, for example Jackson.
POST /rest/sms/templates HTTP/1.1
Host: your-host.com
Accept: application/json
Content-Type: application/json
Cache-Control: no-cache
{
"template": "Hello, ${userName}"
}

parsing form parameters from raw http requests in java

I'm trying to extract some information from raw HTTP Request messages (like the one below) and store them into instances of the org.apache.http.message.BasicHttpRequest (https://hc.apache.org/httpcomponents-core-ga/httpcore/apidocs/index.html) class.
I was able to employ org.apache.http.message.BasicLineParser class and its method parseHeader(String value, LineParser parser) to process (parse + store) the headers, but I don't know how to deal with the parameters passed with the form.
POST https://gist.github.com:443/gists HTTP/1.1
Host: gist.github.com
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en,fr;q=0.8,it-it;q=0.6,it;q=0.4,en-us;q=0.2
Accept-Encoding: gzip, deflate
DNT: 1
Referer: https://gist.github.com/
Connection: keep-alive
Content-Type: multipart/form-data; boundary=-------------------------10314229756379422411656878663
Content-Length: 1242
-----------------------------10314229756379422411656878663
Content-Disposition: form-data; name="parameter_name"
parameter_value
Do you know an utility which can parse the content starting after the header above (i.e. after the first empty line)? What I am interest in collecting are all the pairs <"parameter_name","parameter_value"> present in the request body.
I have already read similar answers/questions such as Parsing raw HTTP Request but I did not find anything helpful on the form-data component
Thanks in advance for your help and time

What you are seeing is MIME encoded content body. HttpClient is content agnostic and therefore does not provide a means of parsing such content. One can however use Apache Mime4J to do so.