[FIXED] How to upload files using JDK 11 java.net.http.HttpClient?

Issue

I recently encountered some problems with java.net.http.HttpClient that comes with JDK 11. I don't know how to use file upload. Found the ofInputStream() in java.net.http.BodyPublishers. I don't know if I using this method file upload. Here are the examples I wrote.

    public HttpResponse<String> post(String url, Supplier<? extends InputStream> streamSupplier, String... headers) throws IOException, InterruptedException {
        HttpRequest.Builder builder = HttpRequest.newBuilder()
                .uri(URI.create(url))
                .headers(headers)
                .POST(null == streamSupplier ?
                        HttpRequest.BodyPublishers.noBody() : HttpRequest.BodyPublishers.ofInputStream(streamSupplier));
        HttpRequest request = builder.build();
        log.debug("Execute HttpClient Method:『{}』, Url:『{}』", request.method(), request.uri().toString());
        return client.send(request, HttpResponse.BodyHandlers.ofString());
    }

Solution

The java.net.http.HttpClient handles bytes supplied through the BodyPublisher as raw body data, without any interpretation. Whether you use HttpRequest.BodyPublishers::ofFile(Path) or HttpRequest.BodyPublishers::ofByteArray(byte[]) is therefore semantically irrelevant: what changes is simply how the bytes that will be transmitted are obtained. In case of file upload - your server probably expects that the request body will be formatted in certain ways. It might also expect some specific headers to be transmitted with the request (such as Content-Type etc). The HttpClient will not do that magically for you. This is something you need to implement at the caller level.

Answered By - daniel

Answer Checked By - Marie Seifert (PHPFixing Admin)