Java okhttp3 only uses http / 1.1 or http / 2

Try to execute some test cases for HTTP requests I want to distinguish between http / 1.1 and HTTP / 2.0 To do this, I need to know which version I used from the request I also want to force requests to use HTTP / 1.1 or http / 2 I'm using okhttp3 for Java

Request request = new Request.Builder()
            .url(url)
            .build();

Response response = client.newCall(request).execute();
return response.body().string();

Solution

You can force the request to be http / 1.1 using the following code

new OkHttpClient.Builder().protocols(Arrays.asList(Protocol.HTTP_1_1));

You cannot force http / 2 because http / 1.1 must be in the protocols list

However, you can confirm this by checking the protocol on the response object

Request request = new Request.Builder()
        .url("http://publicobject.com/helloworld.txt")
        .build();

Response response = client.newCall(request).execute();

assert(response.protocol() == Protocol.HTTP_2);