How to set custom User-Agent with apache http client library 4.1?

How to make HTTPClient use custom User-Agent header?

The following code submits empty user-agent. What am I missing?

import java.io.IOException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.CoreProtocolPNames;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;

public class TestHTTP {

        public static v开发者_高级运维oid main(String[] args) throws ClientProtocolException, IOException {
        HttpGet request = new HttpGet("http://tool.keepmeapi.com/echo");

        HttpContext HTTP_CONTEXT = new BasicHttpContext();
        HTTP_CONTEXT.setAttribute(CoreProtocolPNames.USER_AGENT, "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101206 Ubuntu/10.10 (maverick) Firefox/3.6.13");
        request.setHeader("Referer", "http://www.google.com");

        HttpClient httpClient = new DefaultHttpClient();
        HttpResponse response = httpClient.execute(request, HTTP_CONTEXT);

        if (response.getStatusLine().getStatusCode() < 200 || response.getStatusLine().getStatusCode() >= 400) {
            throw new IOException("Got bad response, error code = " + response.getStatusLine().getStatusCode());
        }

        HttpEntity entity = response.getEntity();
        if (entity != null) {
            System.out.println(EntityUtils.toString(entity));
            EntityUtils.consume(entity);
        }
    }

}

Note: The solution is for users using the old httpcomponents 4.2 and before.

The line

request.setHeader("User-Agent", "MySuperUserAgent");

is missing. Add it and enjoy.

Note: Starting from httpcomponents 4.3 this solution is deprecated.

You can also set a global user agent value instead of per request:

String userAgent = "NewUseAgent/1.0";
HttpClient httpClient = new DefaultHttpClient();
httpclient.getParams().setParameter(CoreProtocolPNames.USER_AGENT, userAgent);

With httpcomponents 4.3 you should use the client builder to set the user agent:

HttpClient httpClient = HttpClients.custom()
                            .setUserAgent("my UserAgent 5.0")
                            .build();

httpClient.execute(new HttpGet("http://www.google.de"));