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package org.nakedobjects.metamodel.commons.lang;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Properties;


/**
 * Adapted from Ibatis Common.
 */
public class Resources {

    /**
     * Returns the URL, or null if not available.
     */
    public static URL getResourceURL(final String resource) {

        // try thread's classloader
        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        URL url = classLoader.getResource(resource);
        if (url != null) {
            return url;
        }

        // try this class' classloader
        classLoader = Resources.class.getClassLoader();
        url = classLoader.getResource(resource);
        if (url != null) {
            return url;
        }

        // try system class loader (could return null)
        // wrapping in a try...catch because when running tests by Maven for a non-existing
        // resource, seems to bomb out. Is okay when run from Eclipse. A bit of a puzzle.
        try {
            return ClassLoader.getSystemResource(resource);
        } catch (final NullPointerException ignore) {
            return null;
        }
    }

    public static InputStream getResourceAsStream(final String resource) {

        // try thread's classloader
        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        InputStream is = classLoader.getResourceAsStream(resource);
        if (is != null) {
            return is;
        }

        // try this class' classloader
        classLoader = Resources.class.getClassLoader();
        is = classLoader.getResourceAsStream(resource);
        if (is != null) {
            return is;
        }

        // try system class loader (could return null)
        // have wrapped in a try...catch because for same reason as getResourceURL
        try {
            return ClassLoader.getSystemResourceAsStream(resource);
        } catch (final NullPointerException ignore) {
            return null;
        }
    }

    public static File getResourceAsFile(final String resource) {
        final URL url = getResourceURL(resource);
        if (url == null) {
            return null;
        }

        return new File(url.getFile());
    }

    public static Properties getResourceAsProperties(final String resource) {

        final InputStream is = getResourceAsStream(resource);
        if (is == null) {
            return null;
        }

        final Properties props = new Properties();
        try {
            props.load(is);
        } catch (final IOException ex) {
            throw new RuntimeException(ex);
        } finally {
            try {
                is.close();
            } catch (final IOException ignore) {
                // ignore
            }
        }

        return props;
    }

}

// Copyright (c) Naked Objects Group Ltd.