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/*
* ================================================================================
* Copyright (c) 2018 AT&T Intellectual Property. 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.
* ============LICENSE_END=========================================================
*
*/
package org.onap.dcae.analytics.model.util.function;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.Optional;
import java.util.Scanner;
import java.util.function.Function;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Simple Function that calls http 'GET' on given URL and returns the response as String if successful. This function
* has side effects and only used for convenience in lambda expressions
* <p>
* NOTE: Suitable for only light weight http get requests as this will be a blocking call
*
* @author Rajiv Singla
*/
public class URLToHttpGetFunction implements Function<URL, Optional<String>> {
private static final Logger logger = LoggerFactory.getLogger(URLToHttpGetFunction.class);
@Override
public Optional<String> apply(final URL url) {
try {
final HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection();
httpConnection.setRequestMethod("GET");
logger.info("Sending 'GET' request to URL : {}", url);
final int responseCode = httpConnection.getResponseCode();
if (responseCode == 200) {
final StringBuilder responseString = new StringBuilder();
try (Scanner scanner = new Scanner(httpConnection.getInputStream(), StandardCharsets.UTF_8.name())) {
while (scanner.hasNext()) {
responseString.append(scanner.next());
}
}
logger.info("Successful Response: {}", responseString);
return Optional.of(responseString.toString());
}
logger.error("Unsuccessful Response Code: {} when calling URL: {}", responseCode, url);
} catch (IOException e) {
logger.error("Unable to create HTTP URL Connection to URL:" + url, e);
}
return Optional.empty();
}
}
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