eu.cloudwave.wp5.feedbackhandler.metricsources.AbstractMetricSourceClient.java Source code

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Here is the source code for eu.cloudwave.wp5.feedbackhandler.metricsources.AbstractMetricSourceClient.java

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/*******************************************************************************
 * Copyright 2015 Software Evolution and Architecture Lab, University of Zurich
 * 
 * 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 eu.cloudwave.wp5.feedbackhandler.metricsources;

import java.io.IOException;

import org.springframework.http.HttpStatus;
import org.springframework.web.client.HttpServerErrorException;
import org.springframework.web.client.HttpStatusCodeException;

import eu.cloudwave.wp5.common.error.ErrorType;

/**
 * An abstract base implementation for {@link MetricSourceClient}'s.
 */
public abstract class AbstractMetricSourceClient implements MetricSourceClient {

    /**
     * This method can be used by subclass for error handling. It directly handles 404 Errors and general errors that are
     * not treated specially and calls the hook {@link #handleHttpServerException(HttpServerErrorException)} for errors
     * that have to be treated specially by subclasses. By implementing the hook methods subclasses can handles those
     * errors individually.
     * 
     * @param throwable
     *          the exception
     * @throws MetricSourceClientException
     *           for errors that do not have to be treated specially by subclasses
     */
    protected final void handleException(final Throwable throwable) throws MetricSourceClientException {
        if (throwable instanceof HttpStatusCodeException) {
            final HttpStatusCodeException httpError = (HttpStatusCodeException) throwable;

            // handle errors individually by subclasses
            try {
                handleHttpServerException(httpError);
            } catch (final IOException e) {
                /**
                 * This error can occur while trying to identify the cause for the original error. It is ignored and the
                 * original error is thrown instead.
                 */
            }

            // handle 404 NOT FOUND errors
            if (httpError.getStatusCode().equals(HttpStatus.NOT_FOUND)) {
                throw new MetricSourceClientException(ErrorType.METRIC_SOURCE_NOT_AVAILABLE, httpError);
            }
        }

        // if no precise cause could be identified, throw the original exception
        throw new MetricSourceClientException(ErrorType.NEW_RELIC__GENERAL, throwable);
    }

    /**
     * Has to be implemented by subclasses to individually handle {@link HttpStatusCodeException}'s.
     * 
     * @param httpError
     *          the HTTP error
     * @throws MetricSourceClientException
     *           according to the particular {@link HttpStatusCodeException}
     * @throws IOException
     *           if the server response error could not be parsed correctly.
     */
    protected abstract void handleHttpServerException(HttpStatusCodeException httpError)
            throws MetricSourceClientException, IOException;

}