Java tutorial
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We also recommend that a * file or class name and description of purpose be included on the * same "printed page" as the copyright notice for easier * identification within third-party archives. * * Copyright 2016 Ian Kelly * * 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 cognitivej.core; import cognitivej.core.error.*; import cognitivej.core.error.exceptions.CognitiveException; import cognitivej.vision.face.CognitiveContext; import com.google.gson.Gson; import com.google.gson.GsonBuilder; import com.mashape.unirest.http.HttpMethod; import com.mashape.unirest.http.HttpResponse; import com.mashape.unirest.http.Unirest; import com.mashape.unirest.http.exceptions.UnirestException; import com.mashape.unirest.request.HttpRequest; import com.mashape.unirest.request.HttpRequestWithBody; import org.apache.commons.io.IOUtils; import org.apache.http.HttpStatus; import org.jetbrains.annotations.NotNull; import org.json.JSONObject; import java.io.IOException; import java.io.InputStream; import java.lang.reflect.Type; import java.util.HashMap; import java.util.Map; public abstract class RestAction<T> { private static final String PROJECTOXFORD_AI = "https://api.projectoxford.ai/"; public static final String IMAGE_INPUT_STREAM_KEY = "imageInputStream"; private final CognitiveContext cognitiveContext; private Map<Integer, ErrorHandler> errorHandlers = new HashMap<>(); private Gson gson; public RestAction(@NotNull CognitiveContext cognitiveContext) { this.cognitiveContext = cognitiveContext; gson = new GsonBuilder().create(); } /** * Invoke the HTTP REST call. * * @return The valid Result from the server */ public T withResult() { return ExponentialBackOff.execute(this::doWork); } private T doWork() { try { setupErrorHandlers(); WorkingContext workingContext = workingContext(); HttpRequest builtRequest = buildUnirest(workingContext).queryString(workingContext.getQueryParams()) .headers(workingContext.getHeaders()) .header("Ocp-Apim-Subscription-Key", cognitiveContext.subscriptionKey); if (!workingContext.getHttpMethod().equals(HttpMethod.GET) && workingContext().getPayload().size() > 0) { buildBody((HttpRequestWithBody) builtRequest); } HttpResponse response; if (typedResponse() == InputStream.class) response = builtRequest.asBinary(); else response = builtRequest.asString(); checkForError(response); return postProcess(typeResponse(response.getBody())); } catch (UnirestException | IOException e) { throw new CognitiveException(e); } } /** * Invoke the HTTP REST call. will not return a response */ public void withNoResult() { withResult(); } private void setupErrorHandlers() { errorHandlers.put(HttpStatus.SC_UNAUTHORIZED, new UnAuthorizedErrorHandler()); errorHandlers.put(HttpStatus.SC_FORBIDDEN, new ForbiddenErrorHandler()); errorHandlers.put(429, new RateLimitExceededErrorHandler()); errorHandlers.put(409, new ConcurrentOperationConflictErrorHandler()); customErrorHandlers(errorHandlers); } private void buildBody(HttpRequestWithBody builtRequest) throws IOException { if (workingContext().getPayload().containsKey(IMAGE_INPUT_STREAM_KEY)) { builtRequest.header("content-type", "application/octet-stream").body( IOUtils.toByteArray((InputStream) workingContext().getPayload().get(IMAGE_INPUT_STREAM_KEY))); } else { builtRequest.header("content-type", "application/json") .body(new JSONObject(workingContext().getPayload())); } } private Object typeResponse(Object responseBody) { if (typedResponse() == null || responseBody instanceof InputStream) return responseBody; return gson.fromJson((String) responseBody, typedResponse()); } private void checkForError(HttpResponse response) { if (response.getStatus() == HttpStatus.SC_ACCEPTED || response.getStatus() == HttpStatus.SC_OK) return; ErrorHandler errorHandler = errorHandlers.getOrDefault(response.getStatus(), new ErrorHandler()); errorHandler.publishError(response); } private HttpRequest buildUnirest(WorkingContext workingContext) { String url = String.format("%s%s", PROJECTOXFORD_AI, workingContext.getPathBuilt()); switch (workingContext.getHttpMethod()) { case GET: return Unirest.get(url); case PUT: return Unirest.put(url); case DELETE: return Unirest.delete(url); case PATCH: return Unirest.patch(url); } return Unirest.post(url); } protected abstract WorkingContext workingContext(); protected Type typedResponse() { return null; } protected void customErrorHandlers(Map<Integer, ErrorHandler> errorHandlers) { } @SuppressWarnings("unchecked") protected T postProcess(Object response) { return (T) response; } }