Custom HTTP Header with the HttpClient

Table of Contents

1. Overview
2. Set Header on Request – 4.3 and Above
3. Set Header on Request – Before 4.3
4. Set Default Header on the Client
5. Conclusion

1. Overview

In this tutorial, we’ll look at how to set a custom header with the HttpClient.

If you want to dig deeper and learn other cool things you can do with the HttpClient – head on over to the main HttpClient tutorial.

2. Set Header on Request – 4.3 and Above

HttpClient 4.3 has introduced a new way of building requests – the RequestBuilder. To set a header, we’ll use the setHeader method – on the builder:

HttpClient client = HttpClients.custom().build();
HttpUriRequest request = RequestBuilder.get()
  .setUri(SAMPLE_URL)
  .setHeader(HttpHeaders.CONTENT_TYPE, "application/json")
  .build();
client.execute(request);

3. Set Header on Request – Before 4.3

In versions pre 4.3 of HttpClient, we can set any custom header on a request with a simple setHeader call on the request:

HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(SAMPLE_URL);
request.setHeader(HttpHeaders.CONTENT_TYPE, "application/json");
client.execute(request);

As we can see, we’re setting the Content-Type directly on the request to a custom value – JSON.

4. Set Default Header on the Client

Instead of setting the Header on each and every request, we can also configure it as a default header on the Client itself:

Header header = new BasicHeader(HttpHeaders.CONTENT_TYPE, "application/json");
List<Header> headers = Lists.newArrayList(header);
HttpClient client = HttpClients.custom().setDefaultHeaders(headers).build();
HttpUriRequest request = RequestBuilder.get().setUri(SAMPLE_URL).build();
client.execute(request);

This is extremely helpful when the header needs to be the same for all requests – such as a custom application header.