com.rathravane.till.persistence.ResourceLoader Maven / Gradle / Ivy

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A small collection of classes used in various Rathravane systems.
There is a newer version: 2.1.1
package com.rathravane.till.persistence;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.AmazonS3URI;
import com.amazonaws.services.s3.model.AmazonS3Exception;
import com.amazonaws.services.s3.model.GetObjectRequest;
import com.amazonaws.services.s3.model.S3Object;
import com.rathravane.till.data.rrStreamTools;

/**
 * ResourceLoader is a general purpose tool for loading a data stream by name.
 * @author peter
 *
 */
public class ResourceLoader
{
	public static InputStream load ( String resource ) throws IOException
	{
		return new ResourceLoader().named ( resource ).load ();
	}

	public ResourceLoader ()
	{
	}

	public ResourceLoader named ( String name )
	{
		fNamed = name;
		return this;
	}

	public InputStream load () throws IOException 
	{
		if ( fNamed == null ) return null;

		if ( fNamed.startsWith ( "s3://" ) )
		{
			return loadFromS3 ( fNamed );
		}
		else if ( fNamed.startsWith ( "http://" ) || fNamed.startsWith ( "https://" ) )
		{
			return loadHttp ( fNamed );
		}

		// otherwise...
		InputStream is = null;

		// try as a file
		final File f = new File ( fNamed );
		if ( f.exists () )
		{
			try
			{
				return new FileInputStream ( fNamed );
			}
			catch ( FileNotFoundException x )
			{
				log.warn ( "File not found after exists() returned true.", x );
			}
		}

		is = ResourceLoader.class.getClassLoader().getResourceAsStream ( fNamed );
		if ( is != null )
		{
			return is;
		}

		// now try the system class loaders' resource finder
		is = ClassLoader.getSystemResourceAsStream ( fNamed );
		if ( is != null )
		{
			return is;
		}

		return null;
	}

	private String fNamed = null;
	private static final Logger log = LoggerFactory.getLogger ( ResourceLoader.class );

	private static InputStream loadFromS3 ( String url ) throws IOException
	{
		final AmazonS3URI uri = new AmazonS3URI ( url );
		final AWSCredentials creds = new AWSCredentials ()
		{
			@Override
			public String getAWSAccessKeyId () { return System.getenv ( "AWS_ACCESS_KEY_ID" ); }

			@Override
			public String getAWSSecretKey () { return System.getenv ( "AWS_SECRET_ACCESS_KEY" ); }
		};
		final AmazonS3Client db = new AmazonS3Client ( creds );

		final ByteArrayOutputStream baos = new ByteArrayOutputStream ();
		S3Object object = null;
		try
		{
			object = db.getObject ( new GetObjectRequest ( uri.getBucket (), uri.getKey () ) );
			final InputStream is = object.getObjectContent ();

			// s3 objects must be closed or will leak an HTTP connection
			rrStreamTools.copyStream ( is, baos );
		}
		catch ( AmazonS3Exception x )
		{
			throw new IOException ( x ); 
		}
		finally
		{
			if ( object != null )
			{
				object.close ();
			}
		}
		return new ByteArrayInputStream ( baos.toByteArray () );
	}

	private static InputStream loadHttp ( String url ) throws IOException
	{
		return new URL ( url ).openStream ();
	}
}