eu.cloudwave.wp5.common.rest.AbstractRestClient.java Source code

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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.common.rest;

import java.io.IOException;
import java.util.Collections;
import java.util.List;

import org.springframework.http.HttpRequest;
import org.springframework.http.client.ClientHttpRequestExecution;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.web.client.RestTemplate;

import com.google.common.collect.ImmutableList;

/**
 * Abstract base implementation for a REST-client.
 */
public abstract class AbstractRestClient {

    private RestTemplate restTemplate;

    public AbstractRestClient() {
        this.restTemplate = new RestTemplate();
    }

    /**
     * Creates a {@link RestTemplate} with the given HTTP headers.
     * 
     * @param requestHeaders
     *          the HTTP headers
     * @return the created {@link RestTemplate}
     */
    protected RestTemplate restTemplate(final RestRequestHeader[] requestHeaders) {
        if (hasHeaders(requestHeaders)) {
            addHeaders(requestHeaders);
        } else {
            final List<ClientHttpRequestInterceptor> interceptors = ImmutableList.of();
            restTemplate.setInterceptors(interceptors);
        }
        return restTemplate;
    }

    private boolean hasHeaders(final RestRequestHeader[] requestHeaders) {
        return requestHeaders != null && requestHeaders.length > 0;
    }

    private void addHeaders(final RestRequestHeader[] requestHeaders) {
        final ClientHttpRequestInterceptor interceptor = new ClientHttpRequestInterceptor() {

            @Override
            public ClientHttpResponse intercept(final HttpRequest request, final byte[] body,
                    final ClientHttpRequestExecution execution) throws IOException {

                for (final RestRequestHeader requestHeader : requestHeaders) {
                    request.getHeaders().add(requestHeader.getKey(), requestHeader.getValue());
                }
                return execution.execute(request, body);
            }
        };
        restTemplate.setInterceptors(Collections.singletonList(interceptor));
    }

}