com.ibm.watson.developer_cloud.util.ResponseUtils.java Source code

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Here is the source code for com.ibm.watson.developer_cloud.util.ResponseUtils.java

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/**
 * Copyright 2017 IBM Corp. All Rights Reserved.
 *
 * 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 com.ibm.watson.developer_cloud.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.stream.JsonReader;
import com.ibm.watson.developer_cloud.service.model.GenericModel;

import okhttp3.Response;

/**
 * Utility class to manage service responses.
 *
 * @see Response
 */
public final class ResponseUtils {
    private static final String ERROR_MESSAGE = "Error reading the http response";
    private static final Logger LOG = Logger.getLogger(ResponseUtils.class.getName());

    private ResponseUtils() {
        // This is a utility class - no instantiation allowed.
    }

    /**
     * Returns the HTTP Response {@link InputStream}.
     *
     * @param response an HTTP response
     * @return the content body as an InputStream
     */
    public static InputStream getInputStream(Response response) {
        return response.body().byteStream();
    }

    /**
     * Return a {@link JsonElement} representation of the response.
     *
     * @param response the Response
     * @return the content body as JSON
     */
    public static JsonElement getJsonElement(Response response) {
        return new JsonParser().parse(response.body().charStream());
    }

    /**
     * Returns a {@link JsonObject} representation of the response.
     *
     * @param response an HTTP response
     * @return the content body as JSONArray
     */
    public static JsonObject getJsonObject(Response response) {
        return getJsonElement(response).getAsJsonObject();
    }

    /**
     * Returns a {@link JsonObject} representation of the provided JSON String.
     *
     * @param jsonString the JSON String
     * @return the content body as a JsonObject
     */
    public static JsonObject getJsonObject(String jsonString) {
        return new JsonParser().parse(jsonString).getAsJsonObject();
    }

    /**
     * Parses the {@link Response} into the POJO representation.
     *
     * @param <T> the generic type to use when parsing the response
     * @param response the HTTP response
     * @param type the type of the response
     * @return the POJO
     */
    public static <T extends GenericModel> T getObject(Response response, Class<? extends T> type) {
        JsonReader reader;
        try {
            reader = new JsonReader(response.body().charStream());
            return GsonSingleton.getGsonWithoutPrettyPrinting().fromJson(reader, type);
        } finally {
            response.body().close();
        }
    }

    /**
     * Returns a String representation of the response.
     *
     * @param response an HTTP response
     * @return the content body as String
     */
    public static String getString(Response response) {
        try {
            return response.body().string();
        } catch (final IOException e) {
            LOG.log(Level.SEVERE, ERROR_MESSAGE, e);
            throw new RuntimeException(ERROR_MESSAGE, e);
        }
    }

}