GWT POST request doesn't include parameters

Keywords:
GWT POST request parameters HTTP HTML RequestBuilder AJAX

Problem:
Following the GWT documentation for making a http-post but it's not clear what the post data should look like if you want it to include form parameters. The newer documentation for com.google.gwt.http.client has a bit more detail but the server side code processing the request (a java servlet) says there's no parameters in the request.

Solution:
It's not in the documentation, but if you want to post form data you must set the "Content-type" header value in the request to "application/x-www-form-urlencoded"

For Example:

StringBuffer postData = new StringBuffer();
// note param pairs are separated by a '&' 
// and each key-value pair is separated by a '='
postData.append(URL.encode("YourParameterName")).append("=").append(URL.encode("YourParameterValue"));
postData.append("&");
postData.append(URL.encode("YourParameterName2")).append("=").append(URL.encode("YourParameterValue2"));

RequestBuilder builder = new RequestBuilder(RequestBuilder.POST, "/yourserver/formprocessor"));
builder.setHeader("Content-type", "application/x-www-form-urlencoded");
try {
  builder.sendRequest(postData.toString(), this /* or other RequestCallback impl*/);
} catch (RequestException e) {
  // handle this
}

Notes:
This sample chapter from the JavaScript™ Phrasebook is useful: Sending a POST Request