Scala Cookbook

15.10. Sending JSON Data to a POST URL

Problem

You want to send JSON data (or other data) to a POST URL, either from a standalone client, or when using a framework that doesn’t provide this type of service.

Solution

Create a JSON string using your favorite JSON library, and then send the data to the POST URL using the Apache HttpClient library. In the following example, the Gson library is used to construct a JSON string, which is then sent to a server using the methods of the HttpClient library:

import java.io._
import org.apache.commons._
import org.apache.http._
import org.apache.http.client._
import org.apache.http.client.methods.HttpPost
import org.apache.http.impl.client.DefaultHttpClient
import java.util.ArrayList
import org.apache.http.message.BasicNameValuePair
import org.apache.http.client.entity.UrlEncodedFormEntity
import com.google.gson.Gson

case class Person(firstName: String, lastName: String, age: Int)

object HttpJsonPostTest extends App {

  // create our object as a json string
  val spock = new Person("Leonard", "Nimoy", 82)
  val spockAsJson = new Gson().toJson(spock)

  // add name value pairs to a post object
  val post = new HttpPost("http://localhost:8080/posttest")
  val nameValuePairs = new ArrayList[NameValuePair]()
  nameValuePairs.add(new BasicNameValuePair("JSON", spockAsJson))
  post.setEntity(new UrlEncodedFormEntity(nameValuePairs))

  // send the post request
  val client = new DefaultHttpClient
  val response = client.execute(post)
  println("--- HEADERS ---")
  response.getAllHeaders ...