AbstractLastFmAuthApiBinding.java

/*
 * Copyright 2011 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.social.lastfm.auth;

import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.converter.ByteArrayHttpMessageConverter;
import org.springframework.http.converter.FormHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.http.converter.json.MappingJacksonHttpMessageConverter;
import org.springframework.social.ApiBinding;
import org.springframework.social.lastfm.api.impl.UserAgentHelper;
import org.springframework.social.lastfm.connect.RestTemplateWithHeaders;
import org.springframework.social.support.ClientHttpRequestFactorySelector;
import org.springframework.web.client.RestTemplate;

/**
 * Base class for LastFm-Auth-based provider API bindings.
 * 
 * @author Michael Lavelle
 */
public abstract class AbstractLastFmAuthApiBinding implements ApiBinding {

	private LastFmAccessGrant lastFmAccessGrant;
 
	private final RestTemplate restTemplate;

	
	
	/**
	 * Constructs the API template without user authorization. This is useful
	 * for accessing operations on a provider's API that do not require user
	 * authorization.
	 */
	protected AbstractLastFmAuthApiBinding() {
		
		this.lastFmAccessGrant = null;
		HttpHeaders headers = new HttpHeaders();
		headers.add("User-Agent", UserAgentHelper.getUserAgent());
		restTemplate = new RestTemplateWithHeaders(
				ClientHttpRequestFactorySelector.getRequestFactory(), headers);
		restTemplate.setMessageConverters(getMessageConverters(true));

		configureRestTemplate(restTemplate);
	}

	/**
	 * Constructs the API template with LastFm credentials necessary to perform
	 * operations on behalf of a user.
	 * 
	 * @param accessToken
	 *            the access token
	 */
	protected AbstractLastFmAuthApiBinding(
			LastFmAccessGrant lastFmAccessGrant) {
		this.lastFmAccessGrant = lastFmAccessGrant;
		HttpHeaders headers = new HttpHeaders();
		headers.add("User-Agent", UserAgentHelper.getUserAgent());

		restTemplate = new RestTemplateWithHeaders(
				ClientHttpRequestFactorySelector.getRequestFactory(), headers);
		restTemplate.setMessageConverters(getMessageConverters(true));
		configureRestTemplate(restTemplate);

	}

	/**
	 * Set the ClientHttpRequestFactory. This is useful when custom
	 * configuration of the request factory is required, such as configuring
	 * custom SSL details.
	 * 
	 * @param requestFactory
	 *            the request factory
	 */
	public void setRequestFactory(ClientHttpRequestFactory requestFactory) {

		restTemplate.setRequestFactory(requestFactory);

	}

	// implementing ApiBinding

	public boolean isAuthorized() {
		return lastFmAccessGrant != null;
	}

	// public implementation operations

	/**
	 * Obtains a reference to the REST client backing this API binding and used
	 * to perform API calls. Callers may use the RestTemplate to invoke other
	 * API operations not yet modeled by the binding interface. Callers may also
	 * modify the configuration of the RestTemplate to support unit testing the
	 * API binding with a mock server in a test environment. During
	 * construction, subclasses may apply customizations to the RestTemplate
	 * needed to invoke a specific API.
	 * 
	 * @see RestTemplate#setMessageConverters(java.util.List)
	 * @see RestTemplate#setErrorHandler(org.springframework.web.client.ResponseErrorHandler)
	 */
	public RestTemplate getRestTemplate() {
		return restTemplate;
	}

	// subclassing hooks

	/**
	 * Subclassing hook to enable customization of the RestTemplate used to
	 * consume provider API resources. An example use case might be to configure
	 * a custom error handler. Note that this method is called after the
	 * RestTemplate has been configured with the message converters returned
	 * from getMessageConverters().
	 * 
	 * @param restTemplate
	 *            the RestTemplate to configure.
	 */
	protected void configureRestTemplate(RestTemplate restTemplate) {
	}

	/**
	 * Returns a list of {@link HttpMessageConverter}s to be used by the
	 * internal {@link RestTemplate}. By default, this includes a
	 * {@link StringHttpMessageConverter}, a
	 * {@link MappingJacksonHttpMessageConverter}, a
	 * {@link ByteArrayHttpMessageConverter}, and a
	 * {@link FormHttpMessageConverter}. The {@link FormHttpMessageConverter} is
	 * set to use "UTF-8" character encoding. Override this method to add
	 * additional message converters or to replace the default list of message
	 * converters.
	 */
	protected List<HttpMessageConverter<?>> getMessageConverters(boolean json) {
		List<HttpMessageConverter<?>> messageConverters = new ArrayList<HttpMessageConverter<?>>();
		messageConverters.add(new StringHttpMessageConverter());
		messageConverters.add(getFormMessageConverter());
		if (json) {
			messageConverters.add(getJsonMessageConverter());
		}
		messageConverters.add(getByteArrayMessageConverter());
		return messageConverters;
	}

	/**
	 * Returns an {@link FormHttpMessageConverter} to be used by the internal
	 * {@link RestTemplate}. By default, the message converter is set to use
	 * "UTF-8" character encoding. Override to customize the message converter
	 * (for example, to set supported media types or message converters for the
	 * parts of a multipart message). To remove/replace this or any of the other
	 * message converters that are registered by default, override the
	 * getMessageConverters() method instead.
	 */
	protected FormHttpMessageConverter getFormMessageConverter() {
		FormHttpMessageConverter converter = new FormHttpMessageConverter();
		converter.setCharset(Charset.forName("UTF-8"));
		return converter;
	}

	/**
	 * Returns a {@link MappingJacksonHttpMessageConverter} to be used by the
	 * internal {@link RestTemplate}. Override to customize the message
	 * converter (for example, to set a custom object mapper or supported media
	 * types). To remove/replace this or any of the other message converters
	 * that are registered by default, override the getMessageConverters()
	 * method instead.
	 */
	protected MappingJackson2HttpMessageConverter getJsonMessageConverter() {
		return new MappingJackson2HttpMessageConverter();
	}

	/**
	 * Returns a {@link ByteArrayHttpMessageConverter} to be used by the
	 * internal {@link RestTemplate} when consuming image or other binary
	 * resources. By default, the message converter supports "image/jpeg",
	 * "image/gif", and "image/png" media types. Override to customize the
	 * message converter (for example, to set supported media types). To
	 * remove/replace this or any of the other message converters that are
	 * registered by default, override the getMessageConverters() method
	 * instead.
	 */
	protected ByteArrayHttpMessageConverter getByteArrayMessageConverter() {
		ByteArrayHttpMessageConverter converter = new ByteArrayHttpMessageConverter();
		converter.setSupportedMediaTypes(Arrays.asList(MediaType.IMAGE_JPEG,
				MediaType.IMAGE_GIF, MediaType.IMAGE_PNG));
		return converter;
	}

}