How to detect org.apache.http.HttpEntity

[tom08zehn]

Probably a very basic question but I couldn't find any good solution so far.

How can I detect all implementing classes of org.apache.http.HttpEntity [Link]?

As org.apache.http.HttpEntity is an interface I cannot use myObj instanceof org.apache.http.HttpEntity.

Background: I have a wrapper function for HTTP requests (shortened version below). If the submitted body is of type HttpEntity then this should be used for the request, otherwise a new StringEntity is created to build the payload.

function http_post_request(url, body, charset) {
    // ...
    var httpPost = new org.apache.http.client.methods.HttpPost(url);
    // detect entity here: var isEntity = body instanceof org.apache.http.HttpEntity; // this doesn't work
    if(!isEntity) body = new StringEntity(body, charset);
    httpPost.setEntity(body);
    // ...
}

[tom08zehn]

I correct myself: body instanceof org.apache.http.HttpEntity does work perfectly well in my case where I do:

org.apache.http.entity.mime.MultipartEntityBuilder.create()
    // ...
    .build();

... what returns type HttpEntity.

I'd like to share my final solution:

var entity = body instanceof org.apache.http.HttpEntity ? body : new StringEntity(body, charset)
httpRequest.setEntity(entity);