"Bad Request: no files uploaded" error While trying to upload a image file with HttpRequest from java client

Question

public static void main(String[] args) throws Exception {            
try {
     HttpClient client = HttpClient.newHttpClient();
     HttpRequest postRequest = (HttpRequest) HttpRequest.newBuilder()
     .uri(new URI("url to upload file and fetch info "))
     .setHeader("Authorization", "Bearer " +tokenKey)
     .setHeader("Content-Type", "multipart/form-data")
    .POST(BodyPublishers.ofFile(Paths.get("\\SpringProject\\ImageProcessing\\src\\image.jpg")))
                .build();
                          
     HttpResponse<String> response = client.send(postRequest, HttpResponse.BodyHandlers.ofString());
     System.out.println(response.body());
} catch(Exception e) {
    e.printStackTrace();
}}

with the above code i am trying to upload a image file and fetch back the details related to that image. But i am getting the below error message from the response body. Please help me to sort out this problem.

{
    "result": "FAILED",
    "data": {
        "error_code": 400004,
        "error_message": "Bad Request: no files uploaded"
    }
} 

Answer 1

I suspect that you have a problem with the line: Paths.get("\\SpringProject\\ImageProcessing\\src\\image.jpg") The problem is that if your parameter to method Paths.get is a valid but non-existent path it will not throw an exception. I.e. path C:\\test is valid regardless of whether this path actually exists or not and path C\#/test\&/ is invalid due to syntactic error. In your case, you provide a relative path. I suggest that you try an absolute path and actually check that it exists before passing it as your parameter. Also if you are interested I may suggest to try and use a simpler 3d party HTTP client. Here how your code may look like:

HttpClient httpClient = new HttpClient();
httpClient.setConnectionUrl("url to upload file and fetch info ");
ResponseHolder<String> responseHolder = null;
try {
    byte[] content = FileUtils.readFileAsByteArray("Absolute path to your file");
    ByteBuffer contentBuff = ByteBuffer.wrap(content);
    Integer length = content.length;
    httpClient.setRequestHeader("content-length", length.toString())
    .setRequestHeader("Authorization", "Bearer " +tokenKey)
    .setRequestHeader("Content-Type", "multipart/form-data");
    responseHolder  = httpClient.sendHttpRequest(HttpClient.HttpMethod.POST, contentBuff);
    String postResponse = responseHolder.getResponseContent();
    System.out.println("Upload (POST) returned String: " + postResponse + "\nresponse: " + responseHolder.getResponseCode() + " " + responseHolder.getResponseMessage());
} catch (IOException ioe) {
    System.out.println(responseHolder.getResponseCode() + " " + responseHolder.getResponseMessage());
}

Note that classes HttpClient and FileUtils in this code come from Open Source MgntUtils library written and maintained by me. Here is HttpClint Javadoc. The library can be obtained from the Maven Central repository or as a jar file from Github (including Javadoc and source code)