org.wso2.carbon.connector.powerbi.auth.PowerBIAccessTokenGenerator.java Source code

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Here is the source code for org.wso2.carbon.connector.powerbi.auth.PowerBIAccessTokenGenerator.java

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/*
 * Copyright (c) 2016, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
 *
 *   WSO2 Inc. licenses this file to you 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.wso2.carbon.connector.powerbi.auth;

import com.google.gson.Gson;
import org.apache.synapse.MessageContext;
import org.json.JSONException;
import org.json.JSONObject;
import org.wso2.carbon.connector.core.AbstractConnector;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.Charset;

/**
 * Class which associate with retrieving access token through refresh token and
 * authorization code.
 **/
public class PowerBIAccessTokenGenerator extends AbstractConnector {

    /**
     * Connector method which is executed at the specified point within the
     * corresponding Synapse template within the connector.
     *
     * @param messageContext
     *           Synapse Message Context
     */
    @Override
    public void connect(MessageContext messageContext) {
        String apiUrl = (String) messageContext.getProperty(Constants.API_URL);
        String requestQuery = (String) messageContext.getProperty(Constants.REQUEST_QUERY);
        JSONObject responseObject = null;
        try {
            responseObject = sendRequest(apiUrl, Constants.HTTP_METHOD, Constants.CONTENT_TYPE, requestQuery);
            messageContext.setProperty(Constants.RESULT_OBJECT, new Gson().toJson(responseObject));
        } catch (IOException ioException) {
            log.error("Failed to contact server:", ioException);
        } catch (JSONException jsonException) {
            log.error("Failed to create Json Object:", jsonException);
        }

    }

    /**
     * Method used to retrieve a JSON object with access token by accessing the
     * web service.
     *
     * @param endPoint
     *           End point to retrieve access token.
     * @param httpMethod
     *           Method type for HTTP call.
     * @param contentType
     *           Content type of the method call.
     * @param requestQuery
     *           Parameters for the method call.
     * @return JSONObject with access token.
     * @throws IOException
     *            If an error occurs on PowerBI API end.
     * @throws JSONException
     *            If an object creation error occurred.
     */
    private JSONObject sendRequest(String endPoint, String httpMethod, String contentType, String requestQuery)
            throws IOException, JSONException {
        HttpURLConnection httpConnection = writeRequest(endPoint, httpMethod, contentType, requestQuery);

        String responseString = readResponse(httpConnection);
        JSONObject jsonObject = null;
        if (isValidJSON(responseString)) {
            jsonObject = new JSONObject(responseString);
        }
        return jsonObject;

    }

    /**
     * Method use to write the request.
     *
     * @param endPoint
     *           End point to retrieve access token.
     * @param httpMethod
     *           Method type for HTTP call.
     * @param contentType
     *           Content type of the method call.
     * @param requestQuery
     *           Parameters for method call.
     * @return HttpURLConnection httpUrlConnection object.
     * @throws IOException
     *            If an error occurs on PowerBI API end.
     */
    private HttpURLConnection writeRequest(String endPoint, String httpMethod, String contentType,
            String requestQuery) throws IOException {

        OutputStream output = null;

        URL url = new URL(endPoint);
        HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection();
        httpConnection.setInstanceFollowRedirects(false);
        httpConnection.setRequestMethod(httpMethod);
        httpConnection.setRequestProperty("Content-Type", contentType);
        httpConnection.setDoOutput(true);
        try {

            output = httpConnection.getOutputStream();
            output.write(requestQuery.getBytes(Charset.defaultCharset()));

        } finally {

            if (output != null) {
                try {
                    output.close();
                } catch (IOException ioException) {
                    log.error("Failed to contact server:", ioException);
                }
            }

        }
        return httpConnection;
    }

    /**
     * Method used to read the response.
     *
     * @param httpConnection
     *           httpUrlConnection object.
     * @return String response string.
     * @throws IOException
     *            If an error occurs reading the response.
     */
    private String readResponse(HttpURLConnection httpConnection) throws IOException {

        InputStream responseStream = null;
        String responseString = null;
        if (httpConnection.getResponseCode() >= 400) {
            responseStream = httpConnection.getErrorStream();
        } else {
            responseStream = httpConnection.getInputStream();
        }

        if (responseStream != null) {

            StringBuilder stringBuilder = new StringBuilder();
            byte[] bytes = new byte[1024];
            int len;

            while ((len = responseStream.read(bytes)) != -1) {
                stringBuilder.append(new String(bytes, 0, len));
            }

            if (!stringBuilder.toString().trim().isEmpty()) {
                responseString = stringBuilder.toString();
            }

        }

        return responseString;
    }

    /**
     * Method used to check for a JSON object.
     *
     * @param json
     *           String query.
     * @return boolean
     *           returns true if valid JSON or returns false.
     */
    private boolean isValidJSON(String json) {

        try {
            new JSONObject(json);
            return true;
        } catch (JSONException ex) {
            return false;
        }
    }
}