server returns java.io.IOException: Server returned HTTP response code: 400 for URL

Question

I am trying to call rest API which is documented like this

curl -X POST "https://url/api/v1/className/doSomething" -H "accept: application/json" -H "Authorization: Bearer token" -H "Content-Type: application/json" -d

Here is my code sends http post. It works good with all http apis I used before but not for this.

        String result = "";

        RequestProcess process = LogManager.getInstance().newProcess();
        process.setProcessName(url);
        process.setRequestContent(requestContent);

        ObjectMapper mapper = new ObjectMapper().registerModule(new Jdk8Module()).registerModule(new JavaTimeModule());


        String rawData = mapper.writeValueAsString(requestContent);

        String charset = "UTF-8";
        HttpURLConnection connection = (HttpURLConnection)new URL(url).openConnection();
        connection.setDoOutput(true);
        connection.setRequestProperty("Accept-Charset", charset);
        connection.setRequestProperty("Content-Type", "application/json;charset=" + charset);
        connection.setRequestProperty("User-Agent", USER_AGENT);
        connection.setRequestMethod("POST");

        try (OutputStream output = connection.getOutputStream()) {
            output.write(rawData.getBytes(charset));
        }

        InputStream inputStream = connection.getInputStream();
        result = StreamUtil.toString(inputStream);

        process.setResponseContent(result);
        LogManager.getInstance().endProcess(process);

        return result;

I am getting an error

java.io.IOException: Server returned HTTP response code: 400 for URL: url

I tried to do the same from postman and it works. Any ideas?

Answer 1

What do you send as Data? at least you should send -d {} for empty data or remove -d

Answer 2

If it is running in POSTMAN, you can get the corresponding curl request from it. By clicking on Code and select cURL from available options.

Answer 3

I've solved it by removing charset in the Content-Type section. After modification this line looks like this

connection.setRequestProperty("Content-Type", "application/json");