D-Net

package eu.dnetlib.validator.service.impls.providers;

import java.io.IOException;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.URL;

import java.net.URLConnection;

import org.apache.commons.io.IOUtils;

import org.apache.log4j.Logger;

public class URLStreamer {

	private transient Logger logger = Logger.getLogger(URLStreamer.class);

	public String getResponse(URL url, int timeout, int delay, int retryDelay, int retryEfforts) throws IOException {

    	try {

			Thread.sleep(delay);

		} catch (InterruptedException e1) {

			logger.error("", e1);

			throw new IOException();

		}

		InputStream inStream = null;

		String ret = null;

		for(int i=1; i<=retryEfforts; i++) {

			try {

				URLConnection urlConn = url.openConnection();

		    	urlConn.setConnectTimeout(timeout);

		    	urlConn.setReadTimeout(timeout);

		    	urlConn.setAllowUserInteraction(false);         

		    	urlConn.setDoOutput(true);

		    	if(urlConn instanceof HttpURLConnection) {

		    		HttpURLConnection huc = (HttpURLConnection) urlConn;

		    		int code = huc.getResponseCode();

		    		if(code < 200 || code >=300) {

		    			logger.error("Status code: "+code+". Retry effort: "+i);

						try {

							logger.debug("Sleeping for "+retryDelay+" millis before retrying");

							Thread.sleep(retryDelay);

						} catch (InterruptedException ex) {

							logger.error("", ex);

							throw new IOException();

						}

		    			continue;

		    		}

		    	}

		    	inStream = urlConn.getInputStream();

		    	ret = IOUtils.toString(inStream, "UTF-8");

			} catch(Exception e) {

				logger.error("Exception raised. Retry effort: "+i, e);

				try {

					logger.debug("Sleeping for "+retryDelay+" millis before retrying");

					Thread.sleep(retryDelay);

				} catch (InterruptedException ex) {

					logger.error("", ex);

					throw new IOException();

				}

				continue;

			} finally {

				if(inStream != null)

					inStream.close();

			}

			return ret;

		}

		return null;

	}

}