Summary: This post is an excerpt from the Scala Cookbook, partially modified for the internet. This is a short recipe, Recipe 15.13, “How to set HTTP headers when sending a web service request.”
Problem
You need to set URL headers when making an HTTP request in Scala.
Solution
The easiest way to set HTTP headers when calling a web service is to use the Apache HttpClient library to set the headers before making the request, as shown in this example:
import org.apache.http.client.methods.HttpGet
import org.apache.http.impl.client.DefaultHttpClient
object SetUrlHeaders extends App {
val url = "http://localhost:9001/baz"
val httpGet = new HttpGet(url)
// set the desired header values
httpGet.setHeader("KEY1", "VALUE1")
httpGet.setHeader("KEY2", "VALUE2")
// execute the request
val client = new DefaultHttpClient
client.execute(httpGet)
client.getConnectionManager.shutdown
}
Discussion
If you don’t have a web server to test against, you can use a tool like HttpTea to see the results of running this program. HttpTea helps to simulate a server in a test environment. Start HttpTea at the command line to listen on port 9001 like this:
$ java -jar HttpTea.jar -l 9001
Now when you run your client program — such as the program shown in the Solution — you should see the following output from HttpTea, including the headers that were set:
Client>>> GET /baz HTTP/1.1 KEY1: VALUE1 KEY2: VALUE2 Host: localhost:9001 Connection: Keep-Alive User-Agent: Apache-HttpClient/4.1.3 (java 1.5)
See Also
- HttpTea
- Apache HttpClient library
- You may also be able to use the Dispatch library for this purpose