ResourceLoader.java

package de.dhbw.humbuch.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Properties;

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

import com.lowagie.text.BadElementException;
import com.lowagie.text.Image;
import com.vaadin.server.StreamResource.StreamSource;

/**
 * Util class for loading image, text and binary resources
 * 
 * @author davherrmann
 * @author Benjamin Räthlein
 */
public class ResourceLoader implements StreamSource{
	private static final long serialVersionUID = 7205541400825272604L;
	private final static Logger LOG = LoggerFactory
			.getLogger(ResourceLoader.class);

	private String name = "";

	/**
	 * Sets the name of the resource to load
	 * 
	 * @param name
	 *            filename of the resource including the relative or absolute
	 *            path
	 */
	public ResourceLoader(String name) {
		this.name = name;
	}

	/**
	 * Provides a stream to the specified resource
	 * 
	 * @return {@link InputStream} to the resource
	 */
	public InputStream getStream() {
		ClassLoader classLoader = Thread.currentThread()
				.getContextClassLoader();
		return classLoader.getResourceAsStream(name);
	}

	/**
	 * Read content from the specified file
	 * 
	 * @return content of the file as {@link String} if no error occurred,
	 *         otherwise an empty {@link String}
	 */
	public String getContent() {
		StringBuilder stringBuilder = new StringBuilder();

		if (getStream() == null) {
			LOG.error("stream to file '" + name + "' is null");
		} else {
			BufferedReader bufferedReader = new BufferedReader(
					new InputStreamReader(getStream()));

			try {
				String line;
				while ((line = bufferedReader.readLine()) != null) {
					stringBuilder.append(line).append("\n");
				}
				return stringBuilder.toString();
			} catch (IOException ex) {
				LOG.error("couldn't read " + name);
			}
		}

		return null;
	}
	
	/**
	 * Return specified file as Image object
	 * 
	 * @return content of the file as {@link Image} if no error occurred,
	 *         otherwise null
	 */
	public Image getImage() {
		if (getStream() == null) {
			LOG.error("stream to file '" + name + "' is null");
		}
		else {
			int bufferLength = 8192;
			byte[] buffer = new byte[bufferLength];
			InputStream inputStream = getStream();

			try {
				ArrayList<byte[]> buffers = new ArrayList<>();
				int readByte = inputStream.read(buffer, 0, bufferLength);
				buffers.add(buffer);
				
				while (readByte == bufferLength) {
					buffer = new byte[bufferLength];
					readByte = inputStream.read(buffer, 0, bufferLength);
					buffers.add(buffer);
				}

				ByteBuffer byteBuffer = ByteBuffer.allocate(buffers.size()*bufferLength);
				for(byte[] b : buffers) {
					byteBuffer.put(b);
				}
				
				return Image.getInstance(byteBuffer.array());
			}
			catch (IOException | BadElementException ex) {
				LOG.error("couldn't read " + name);
			}
		}

		return null;
	}

	/**
	 * Load properties from the specified file
	 * 
	 * @return {@link Properties}
	 */
	public Properties loadProperties() {
		Properties properties = new Properties();
		try {
			properties.load(getStream());
		} catch (IOException e) {
			LOG.error(e.getMessage());
		}
		return properties;
	}
}