uk.ac.sanger.cgp.dbcon.util.resources.UrlResource.java Source code

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Here is the source code for uk.ac.sanger.cgp.dbcon.util.resources.UrlResource.java

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/*
##########################################################################
#                          COPYRIGHT NOTICE                              #
##########################################################################
#                                                                        #
# Copyright (c) 2006 Genome Research Ltd.                                #
# Author: The Cancer Genome Project IT group cancerit@sanger.ac.uk       #
#                                                                        #
# THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       #
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     #
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. #
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   #
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   #
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      #
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 #
#                                                                        #
# This code is free software; you can redistribute it and/or modify it   #
# under the terms of the BSD License.                                    #
#                                                                        #
# Any redistribution or derivation in whole or in part including any     #
# substantial portion of this code must include this copyright and       #
# permission notice.                                                     #
#                                                                        #
##########################################################################
*/

package uk.ac.sanger.cgp.dbcon.util.resources;

import java.io.ByteArrayInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;

import org.apache.commons.io.IOUtils;

import uk.ac.sanger.cgp.dbcon.exceptions.DbConException;
import uk.ac.sanger.cgp.dbcon.util.InputOutputUtils;

/**
 * Implementation of the resource pattern which streams input from valid
 * URLs and will also clean up error streams if an exception is
 * detected. This is very important in the Sun implementation of the URL
 * classes since the Java VM is not fast enough to clear the backlog itself
 * and this will cause a decrease in the number of available sockets on the 
 * machine (normally these are idle sockets as well)
 * 
 * @author ayates
 */
public class UrlResource extends AbstractResource {

    public UrlResource(String location) {
        super(location);
    }

    protected InputStream getActualInputStream() {
        InputStream is = null;
        URLConnection connection = null;

        try {
            URL url = URI.create(getLocation()).toURL();
            connection = url.openConnection();
            connection.connect();
            InputStream bytesInput = connection.getInputStream();
            byte[] bytes = IOUtils.toByteArray(bytesInput);
            is = new ByteArrayInputStream(bytes);
        } catch (MalformedURLException e) {
            cleanUpHttpURLConnection(connection);
            throw new DbConException("Detected a malformed URL; aborting", e);
        } catch (FileNotFoundException e) {
            cleanUpHttpURLConnection(connection);
            throw new DbConException("Could not find the specified file at the given URL", e);
        } catch (IOException e) {
            cleanUpHttpURLConnection(connection);
            throw new DbConException("Detected IO problems whilst reading URL's content", e);
        }

        return is;
    }

    /**
     * Used to provide a clean up procedure when dealing with URLs
     */
    private void cleanUpHttpURLConnection(URLConnection connection) throws DbConException {

        if (connection == null) {
            getLog().fatal("Input HttpURLConnection was null ... will not perform cleanup");
        } else if (HttpURLConnection.class.isAssignableFrom(connection.getClass())) {
            InputStream errorStream = null;
            try {
                HttpURLConnection httpUrlConnection = (HttpURLConnection) connection;
                errorStream = httpUrlConnection.getErrorStream();
                if (errorStream != null) {
                    byte[] errorOutput = IOUtils.toByteArray(errorStream);
                    if (getLog().isDebugEnabled()) {
                        String lengthOfError = (errorOutput == null) ? "NULL STREAM"
                                : Integer.toString(errorOutput.length);
                        getLog().debug("Length of error stream (in bytes): " + lengthOfError);
                    }
                }

                int responseCode = httpUrlConnection.getResponseCode();
                if (getLog().isDebugEnabled()) {
                    getLog().debug("Detected response code: " + responseCode);
                }

            } catch (IOException e) {
                throw new DbConException("Detected IOException when retriving errorStream", e);
            } finally {
                InputOutputUtils.closeQuietly(errorStream);
            }
        } else {
            getLog().debug("Input URLConnection was not a HttpURLConnection; " + "will not perform cleanup");
        }
    }
}