Spring for Android form data post to server

HttpPostFormDataActivity.java

/*
 * Copyright 2010-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.android.showcase.rest;

import org.springframework.android.showcase.AbstractAsyncActivity;
import org.springframework.android.showcase.R;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;

import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

/**
 * @author Roy Clarkson
 */
public class HttpPostFormDataActivity extends AbstractAsyncActivity {

	protected static final String TAG = HttpPostFormDataActivity.class.getSimpleName();

	// ***************************************
	// Activity methods
	// ***************************************
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		this.setContentView(R.layout.http_post_form_data_layout);

		// Initiate the POST request when the button is selected
		final Button button = (Button) findViewById(R.id.button_post_form_data);
		button.setOnClickListener(new View.OnClickListener() {
			public void onClick(View v) {
				new PostMessageTask().execute();
			}
		});
	}

	// ***************************************
	// Private methods
	// ***************************************
	private void showResult(String result) {
		if (result != null) {
			// display a notification to the user with the response information
			Toast.makeText(this, result, Toast.LENGTH_LONG).show();
		} else {
			Toast.makeText(this, "I got null, something happened!", Toast.LENGTH_LONG).show();
		}
	}

	// ***************************************
	// Private classes
	// ***************************************
	private class PostMessageTask extends AsyncTask<Void, Void, String> {

		private MultiValueMap<String, Object> formData;

		@Override
		protected void onPreExecute() {
			showLoadingProgressDialog();

			Resource resource = new ClassPathResource("res/drawable/spring09_logo.png");

			// populate the data to post
			formData = new LinkedMultiValueMap<String, Object>();
			formData.add("description", "Spring logo");
			formData.add("file", resource);
		}

		@Override
		protected String doInBackground(Void... params) {
			try {
				// The URL for making the POST request
				final String url = getString(R.string.base_uri) + "/postformdata";

				HttpHeaders requestHeaders = new HttpHeaders();

				// Sending multipart/form-data
				requestHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);

				// Populate the MultiValueMap being serialized and headers in an HttpEntity object to use for the request
				HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<MultiValueMap<String, Object>>(
						formData, requestHeaders);

				// Create a new RestTemplate instance
				RestTemplate restTemplate = new RestTemplate(true);

				// Make the network request, posting the message, expecting a String in response from the server
				ResponseEntity<String> response = restTemplate.exchange(url, HttpMethod.POST, requestEntity,
						String.class);

				// Return the response body to display to the user
				return response.getBody();
			} catch (Exception e) {
				Log.e(TAG, e.getMessage(), e);
			}

			return null;
		}

		@Override
		protected void onPostExecute(String result) {
			dismissProgressDialog();
			showResult(result);
		}

	}

}