Java tutorial
/* * Copyright 2016 Johns Hopkins University * * 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.dataconservancy.cos.osf.client.service; import com.fasterxml.jackson.databind.ObjectMapper; import com.github.jasminb.jsonapi.ResourceConverter; import com.github.jasminb.jsonapi.annotations.Type; import com.github.jasminb.jsonapi.retrofit.JSONAPIConverterFactory; import com.squareup.okhttp.OkHttpClient; import com.squareup.okhttp.Request; import io.github.lukehutch.fastclasspathscanner.FastClasspathScanner; import org.dataconservancy.cos.osf.client.config.JacksonOsfConfigurationService; import org.dataconservancy.cos.osf.client.config.JacksonWbConfigurationService; import org.dataconservancy.cos.osf.client.config.OsfConfigurationService; import org.dataconservancy.cos.osf.client.config.WbConfigurationService; import org.dataconservancy.cos.osf.client.support.AuthInterceptor; import retrofit.Retrofit; import java.io.IOException; import java.util.ArrayList; import java.util.List; /** * Factory which wires collaborating objects and produces a Retrofit service interface. * <p> * Defaults for this factory, when not supplied on construction, are: * </p> * <ul> * <li>OsfConfigurationService: JacksonOsfConfigurationService</li> * <li>WbConfigurationService: JacksonWbConfigurationService</li> * <li>OkHttpClient: OkHttpClient (no abstraction)</li> * <li>JSONAPIConverterFactory: JSONAPIConverterFactory (no abstraction)</li> * <li>Default configuration location: /org/dataconservancy/osf/client/config/osf-client.json</li> * </ul> * <p> * This facade hides a lot of complex boilerplate used to configure a Retrofit instance of {@link OsfService}. Retrofit * requires three things: * </p> * <ul> * <li>The base URL of the JSON api</li> * <li>An implementation of {@link retrofit.Converter.Factory}</li> * <li>An HTTP client</li> * </ul> * <p> * The base URL of the JSON api is obtained from the {@link OsfConfigurationService}, the {@code Converter.Factory} * implementation is supplied by an instance of {@link JSONAPIConverterFactory}, and the HTTP client is an instance * of the {@link OkHttpClient}. The different constructors all result in building these collaborators in different * ways. They are either supplied by the caller on construction (in which case they are expected to be fully * configured), or default implementations are instantiated and configured within the constructor. * </p> * <h3>Example usage</h3> * <h4>Typical usage</h4> * <pre> * RetrofitOsfServiceFactory factory = new RetrofitOsfServiceFactory(); * // default configuration resolves to /org/dataconservancy/cos/osf/client/config/osf-client.json * OsfService osfService = factory.getOsfService(OsfService.class); * </pre> * <h4>Custom configuration resource</h4> * <pre> * RetrofitOsfServiceFactory factory = new RetrofitOsfServiceFactory("custom-client-config.json"); * // custom-client-config.json resolved to /org/dataconservancy/cos/osf/client/config/custom-client-config.json * OsfService osfService = factory.getOsfService(OsfService.class); * </pre> * <h4>Custom JSONAPIConverter</h4> * <pre> * List<Class<?>> domainClasses = new ArrayList<>(); * // Add classes annotated with @Type, indicating their participation in the JSON-API Converter framework * domainClasses.add(Foo.class); * domainClasses.add(Bar.class); * * ObjectMapper mapper = new ObjectMapper(); * // Configure the Jackson ObjectMapper if you wish * * // Instantiate the ResourceConverter using the domain classes and ObjectMapper * ResourceConverter resourceConverter = new ResourceConverter(mapper, domainClasses.toArray(new Class[]{})); * * // If you don't plan on resolving links encountered in JSON documents, you can skip the instantiation * // and configuration of the global resolver. * * // Instantiate your favorite HTTP client. It could be OkHttp or any other library. * OkHttpClient httpClient = new OkHttpClient(); * * // Add a global resolver implementation used by the ResourceConverter to resolve URLs encountered in * // JSON documents * resourceConverter.setGlobalResolver(relUrl -> { * com.squareup.okhttp.Call req = httpClient.newCall(new Request.Builder().url(relUrl).build()); * try { * return req.execute().body().bytes(); * } catch (IOException e) { * throw new RuntimeException(e.getMessage(), e); * } * }); * * // Finally instantiate the JSONAPIConverterFactory * JSONAPIConverterFactory jsonApiConverterFactory = new JSONAPIConverterFactory(resourceConverter); * * RetrofitOsfServiceFactory factory = new RetrofitOsfServiceFactory(jsonApiConverterFactory); * // default configuration resolves to /org/dataconservancy/cos/osf/client/config/osf-client.json * OsfService osfService = factory.getOsfService(OsfService.class); * </pre> * Other configuration exercises are left to the reader. */ public class RetrofitOsfServiceFactory { /** * Parameters are: class name, error message */ private static final String ERR_CONFIGURING_CLASS = "Unable to configure the %s: %s"; private static final String DEFAULT_CONFIGURATION_RESOURCE = "osf-client.json"; private static final String NOT_NULL_IAE = "%s must not be null."; /** * Configured OSF configuration service, provides access to the base URL of the OSF v2 API */ private final OsfConfigurationService osfConfigSvc; /** * Configured Waterbutler configuration service, provides access to the base URL of the v1 Waterbutler API */ private final WbConfigurationService wbConfigSvc; /** * The OK HTTP client used by Retrofit for HTTP requests */ private final OkHttpClient httpClient; /** * The JSON-API converter factory used to map JSON documents to Java objects. */ private final JSONAPIConverterFactory jsonApiConverterFactory; /** * Constructs a new RetrofitOsfServiceFactory with the default JSON configuration classpath resource. * Default implementations of the OSF and Waterbutler configuration services, Jackson {@code ObjectMapper}, and * {@code OkHttpClient} will be used. By default this constructor will look for a classpath resource at * {@code /org/dataconservancy/cos/osf/client/config/osf-client.json}. */ public RetrofitOsfServiceFactory() { this(DEFAULT_CONFIGURATION_RESOURCE); } /** * Constructs a new RetrofitOsfServiceFactory with the supplied JSON configuration classpath resource. * Default implementations of the OSF and Waterbutler configuration services, Jackson {@code ObjectMapper}, and * {@code OkHttpClient} will be used. If the classpath resource is <em>not</em> absolute (beginning with a * '{@code /}'), then this constructor will resolve the resource under * {@code /org/dataconservancy/cos/osf/client/config/}. This constructor adds the {@link AuthInterceptor} to the * {@code OkHttpClient} if an {@code authHeader} is found in the configuration for the OSF v2 API. It will * scan the classpath under {@code org.dataconservancy.cos.osf.client.model} for classes with the {@link Type} * annotation, and add them to the {@link com.github.jasminb.jsonapi.ResourceConverter} used to convert JSON * documents to Java objects. The {@code ResourceConverter} is also configured to resolve urls using the * {@code OkHttpClient}. * * @param jsonConfigurationResource classpath resource containing the JSON configuration for the OSF and Waterbutler * HTTP endpoints */ public RetrofitOsfServiceFactory(String jsonConfigurationResource) { try { this.osfConfigSvc = new JacksonOsfConfigurationService(jsonConfigurationResource); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonOsfConfigurationService.class.getName(), e.getMessage()), e); } try { this.wbConfigSvc = new JacksonWbConfigurationService(jsonConfigurationResource); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonWbConfigurationService.class.getName(), e.getMessage()), e); } this.httpClient = new OkHttpClient(); if (osfConfigSvc.getConfiguration().getAuthHeader() != null) { httpClient.interceptors().add(new AuthInterceptor(osfConfigSvc.getConfiguration().getAuthHeader())); } // ... the JSON-API converter used by Retrofit to map JSON documents to Java objects List<Class<?>> domainClasses = new ArrayList<>(); new FastClasspathScanner("org.dataconservancy.cos.osf.client.model") .matchClassesWithAnnotation(Type.class, domainClasses::add).scan(); ResourceConverter resourceConverter = new ResourceConverter(new ObjectMapper(), domainClasses.toArray(new Class[] {})); resourceConverter.setGlobalResolver(relUrl -> { com.squareup.okhttp.Call req = httpClient.newCall(new Request.Builder().url(relUrl).build()); try { return req.execute().body().bytes(); } catch (IOException e) { throw new RuntimeException(e.getMessage(), e); } }); try { this.jsonApiConverterFactory = new JSONAPIConverterFactory(resourceConverter); } catch (Exception e) { throw new IllegalStateException( String.format(ERR_CONFIGURING_CLASS, JSONAPIConverterFactory.class.getName(), e.getMessage()), e); } } /** * Constructs a new RetrofitOsfServiceFactory with the supplied JSON API converter factory. * Default implementations of the OSF and Waterbutler configuration services and {@code OkHttpClient} will be used. * By default this constructor will look for a classpath resource at * {@code /org/dataconservancy/cos/osf/client/config/osf-client.json}. This constructor adds the * {@link AuthInterceptor} to the {@code OkHttpClient} if an {@code authHeader} is found in the configuration for * the OSF v2 API. * * @param jsonApiConverterFactory the configured Retrofit {@code retrofit.Converter.Factory} to use */ public RetrofitOsfServiceFactory(JSONAPIConverterFactory jsonApiConverterFactory) { if (jsonApiConverterFactory == null) { throw new IllegalArgumentException( String.format(NOT_NULL_IAE, JSONAPIConverterFactory.class.getName())); } this.jsonApiConverterFactory = jsonApiConverterFactory; try { this.osfConfigSvc = new JacksonOsfConfigurationService(DEFAULT_CONFIGURATION_RESOURCE); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonOsfConfigurationService.class.getName(), e.getMessage()), e); } try { this.wbConfigSvc = new JacksonWbConfigurationService(DEFAULT_CONFIGURATION_RESOURCE); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonWbConfigurationService.class.getName(), e.getMessage()), e); } this.httpClient = new OkHttpClient(); if (osfConfigSvc.getConfiguration().getAuthHeader() != null) { httpClient.interceptors().add(new AuthInterceptor(osfConfigSvc.getConfiguration().getAuthHeader())); } } /** * Constructs a new RetrofitOsfServiceFactory with the supplied JSON API converter factory and configuration * resource. Default implementations of the OSF and Waterbutler configuration services and {@code OkHttpClient} will * be used. If the classpath resource is <em>not</em> absolute (beginning with a '{@code /}'), then this constructor * will resolve the resource under {@code /org/dataconservancy/cos/osf/client/config/}. This constructor adds the * {@link AuthInterceptor} to the {@code OkHttpClient} if an {@code authHeader} is found in the configuration for * the OSF v2 API. * * @param jsonConfigurationResource classpath resource containing the JSON configuration for the OSF and Waterbutler * HTTP endpoints * @param jsonApiConverterFactory the configured Retrofit {@code retrofit.Converter.Factory} to use */ public RetrofitOsfServiceFactory(String jsonConfigurationResource, JSONAPIConverterFactory jsonApiConverterFactory) { if (jsonApiConverterFactory == null) { throw new IllegalArgumentException( String.format(NOT_NULL_IAE, JSONAPIConverterFactory.class.getName())); } this.jsonApiConverterFactory = jsonApiConverterFactory; try { this.osfConfigSvc = new JacksonOsfConfigurationService(jsonConfigurationResource); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonOsfConfigurationService.class.getName(), e.getMessage()), e); } try { this.wbConfigSvc = new JacksonWbConfigurationService(jsonConfigurationResource); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonWbConfigurationService.class.getName(), e.getMessage()), e); } this.httpClient = new OkHttpClient(); if (osfConfigSvc.getConfiguration().getAuthHeader() != null) { httpClient.interceptors().add(new AuthInterceptor(osfConfigSvc.getConfiguration().getAuthHeader())); } } /** * Constructs a new RetrofitOsfServiceFactory with the default OSF and Waterbutler configuration services. By * default this constructor will look for a classpath resource at * {@code /org/dataconservancy/cos/osf/client/config/osf-client.json} in order to configure the * {@code WbConfigurationService} and {@code OsfConfigurationService}. * * @param httpClient the OK HTTP Client * @param jsonApiConverterFactory the JSON API converter factory */ public RetrofitOsfServiceFactory(JSONAPIConverterFactory jsonApiConverterFactory, OkHttpClient httpClient) { if (httpClient == null) { throw new IllegalArgumentException(String.format(NOT_NULL_IAE, OkHttpClient.class.getName())); } if (jsonApiConverterFactory == null) { throw new IllegalArgumentException( String.format(NOT_NULL_IAE, JSONAPIConverterFactory.class.getName())); } try { this.osfConfigSvc = new JacksonOsfConfigurationService(DEFAULT_CONFIGURATION_RESOURCE); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonOsfConfigurationService.class.getName(), e.getMessage()), e); } try { this.wbConfigSvc = new JacksonWbConfigurationService(DEFAULT_CONFIGURATION_RESOURCE); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonWbConfigurationService.class.getName(), e.getMessage()), e); } this.jsonApiConverterFactory = jsonApiConverterFactory; this.httpClient = httpClient; } /** * Constructs a new RetrofitOsfServiceFactory with the default Waterbutler configuration service. By * default this constructor will look for a classpath resource at * {@code /org/dataconservancy/cos/osf/client/config/osf-client.json} in order to configure the * {@code JacksonWbConfigurationService}. * * @param osfConfigSvc the OSF configuration service * @param httpClient the OK HTTP Client * @param jsonApiConverterFactory the JSON API converter factory */ public RetrofitOsfServiceFactory(OsfConfigurationService osfConfigSvc, OkHttpClient httpClient, JSONAPIConverterFactory jsonApiConverterFactory) { if (osfConfigSvc == null) { throw new IllegalArgumentException( String.format(NOT_NULL_IAE, OsfConfigurationService.class.getName())); } if (httpClient == null) { throw new IllegalArgumentException(String.format(NOT_NULL_IAE, OkHttpClient.class.getName())); } if (jsonApiConverterFactory == null) { throw new IllegalArgumentException( String.format(NOT_NULL_IAE, JSONAPIConverterFactory.class.getName())); } this.osfConfigSvc = osfConfigSvc; try { this.wbConfigSvc = new JacksonWbConfigurationService(DEFAULT_CONFIGURATION_RESOURCE); } catch (Exception e) { throw new IllegalStateException( String.format(ERR_CONFIGURING_CLASS, WbConfigurationService.class.getName(), e.getMessage()), e); } this.httpClient = httpClient; this.jsonApiConverterFactory = jsonApiConverterFactory; } /** * Constructs a new RetrofitOsfServiceFactory with the default OSF configuration service. By * default this constructor will look for a classpath resource at * {@code /org/dataconservancy/cos/osf/client/config/osf-client.json} in order to configure the * {@code JacksonOsfConfigurationService}. * * @param wbConfigSvc the Waterbutler configuration service * @param httpClient the OK HTTP Client * @param jsonApiConverterFactory the JSON API converter factory */ public RetrofitOsfServiceFactory(WbConfigurationService wbConfigSvc, OkHttpClient httpClient, JSONAPIConverterFactory jsonApiConverterFactory) { if (wbConfigSvc == null) { throw new IllegalArgumentException(String.format(NOT_NULL_IAE, WbConfigurationService.class.getName())); } if (httpClient == null) { throw new IllegalArgumentException(String.format(NOT_NULL_IAE, OkHttpClient.class.getName())); } if (jsonApiConverterFactory == null) { throw new IllegalArgumentException( String.format(NOT_NULL_IAE, JSONAPIConverterFactory.class.getName())); } try { this.osfConfigSvc = new JacksonOsfConfigurationService(DEFAULT_CONFIGURATION_RESOURCE); } catch (Exception e) { throw new IllegalStateException(String.format(ERR_CONFIGURING_CLASS, JacksonOsfConfigurationService.class.getName(), e.getMessage()), e); } this.wbConfigSvc = wbConfigSvc; this.httpClient = httpClient; this.jsonApiConverterFactory = jsonApiConverterFactory; } /** * Constructs a new RetrofitOsfServiceFactory with all the required collaborators. * * @param osfConfigSvc the OSF configuration service * @param wbConfigSvc the Waterbutler configuration service * @param httpClient the OK HTTP Client * @param jsonApiConverterFactory the JSON API converter factory * */ public RetrofitOsfServiceFactory(OsfConfigurationService osfConfigSvc, WbConfigurationService wbConfigSvc, OkHttpClient httpClient, JSONAPIConverterFactory jsonApiConverterFactory) { if (osfConfigSvc == null) { throw new IllegalArgumentException( String.format(NOT_NULL_IAE, OsfConfigurationService.class.getName())); } if (wbConfigSvc == null) { throw new IllegalArgumentException(String.format(NOT_NULL_IAE, WbConfigurationService.class.getName())); } if (httpClient == null) { throw new IllegalArgumentException(String.format(NOT_NULL_IAE, OkHttpClient.class.getName())); } if (jsonApiConverterFactory == null) { throw new IllegalArgumentException( String.format(NOT_NULL_IAE, JSONAPIConverterFactory.class.getName())); } this.osfConfigSvc = osfConfigSvc; this.wbConfigSvc = wbConfigSvc; this.httpClient = httpClient; this.jsonApiConverterFactory = jsonApiConverterFactory; } /** * Answers a configured Retrofit-based OSF client that communicates with the OSF V2 API at the base URL obtained * from the OSF configuration service. The JSON responses from the OSF V2 API will be mapped to Java objects * according to the JSON API converter factory. HTTP requests and responses are sent via the OK HTTP client. * * @param osfService the Retrofit interface that contains the methods used by the developer to communicate with the * OSF API. * @param <T> the Retrofit interface type * @return a configured Retrofit interface, ready to service requests. */ public <T> T getOsfService(Class<T> osfService) { Retrofit retrofit = new Retrofit.Builder().baseUrl(osfConfigSvc.getConfiguration().getBaseUri().toString()) .addConverterFactory(jsonApiConverterFactory).client(httpClient).build(); return retrofit.create(osfService); } }