PropertiesLoaderUtils

/**
 * Convenient utility methods for loading of <code>java.util.Properties</code>,
 * performing standard handling of input streams.
 *
 * <p>For more configurable properties loading, including the option of a
 * customized encoding, consider using the PropertiesLoaderSupport class.
 *
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @since 2.0
 * @see PropertiesLoaderSupport
 */
public abstract class PropertiesLoaderUtils {

	/**
	 * Load properties from the given resource.
	 * @param resource the resource to load from
	 * @return the populated Properties instance
	 * @throws IOException if loading failed
	 */
	public static Properties loadProperties(Resource resource) throws IOException {
		Properties props = new Properties();
		fillProperties(props, resource);
		return props;
	}

	/**
	 * Fill the given properties from the given resource.
	 * @param props the Properties instance to fill
	 * @param resource the resource to load from
	 * @throws IOException if loading failed
	 */
	public static void fillProperties(Properties props, Resource resource) throws IOException {
		InputStream is = resource.getInputStream();
		try {
			props.load(is);
		}
		finally {
			is.close();
		}
	}

	/**
	 * Load all properties from the given class path resource,
	 * using the default class loader.
	 * <p>Merges properties if more than one resource of the same name
	 * found in the class path.
	 * @param resourceName the name of the class path resource
	 * @return the populated Properties instance
	 * @throws IOException if loading failed
	 */
	public static Properties loadAllProperties(String resourceName) throws IOException {
		return loadAllProperties(resourceName, null);
	}

	/**
	 * Load all properties from the given class path resource,
	 * using the given class loader.
	 * <p>Merges properties if more than one resource of the same name
	 * found in the class path.
	 * @param resourceName the name of the class path resource
	 * @param classLoader the ClassLoader to use for loading
	 * (or <code>null</code> to use the default class loader)
	 * @return the populated Properties instance
	 * @throws IOException if loading failed
	 */
	public static Properties loadAllProperties(String resourceName, ClassLoader classLoader) throws IOException {
		Assert.notNull(resourceName, "Resource name must not be null");
		ClassLoader clToUse = classLoader;
		if (clToUse == null) {
			clToUse = ClassUtils.getDefaultClassLoader();
		}
		Properties properties = new Properties();
		Enumeration urls = clToUse.getResources(resourceName);
		while (urls.hasMoreElements()) {
			URL url = (URL) urls.nextElement();
			InputStream is = null;
			try {
				URLConnection con = url.openConnection();
				con.setUseCaches(false);
				is = con.getInputStream();
				properties.load(is);
			}
			finally {
				if (is != null) {
					is.close();
				}
			}
		}
		return properties;
	}

}