narya/src/java/com/threerings/resource/ResourceManager.java

//
// $Id: ResourceManager.java,v 1.1 2001/07/18 21:16:12 mdb Exp $

package com.threerings.resource;

import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * The resource manager is responsible for maintaining a repository of
 * resources that are synchronized with a remote source. This is
 * accomplished in the form of a set of jar files that contain resources
 * and that are updated from a remote resource repository via HTTP.
 */
public class ResourceManager
{
    /**
     * Temporary means by which to construct a resource manager that loads
     * resources from the specified source.
     */
    public ResourceManager (URL source)
    {
        _source = source;
        _rootPath = _source.getPath();
        // make root path end with a slash
        if (!_rootPath.endsWith("/")) {
            _rootPath = _rootPath + "/";
        }
    }

    /**
     * Fetches a resource from the local repository.
     *
     * @param path the path to the resource
     * (ie. "config/miso.properties"). This should not begin with a slash.
     *
     * @exception IOException thrown if a problem occurs locating or
     * reading the resource.
     */
    public InputStream getResource (String path)
        throws IOException
    {
        try {
            String rpath = _rootPath + path;
            URL rurl = new URL(_source, rpath);
            return rurl.openStream();

        } catch (MalformedURLException mue) {
            Log.warning("Unable to construct path to resource " +
                        "[path=" + path + "].");
            return null;
        }
    }

    /**
     * Fetches the requested resource and loads its contents into a byte
     * array, which is returned. Note: this is hugely inefficient because
     * the data is copied twice while reading and then once entirely again
     * when a brand new byte array is returned for you, the caller (thanks
     * to the inflexibility of <code>ByteArrayOutputStream</code>). Anyone
     * reading a lot of resources should obtain an
     * <code>InputStream</code> and read the data directly into where it
     * needs to go.
     *
     * @exception IOException thrown if a problem occurs locating or
     * reading the resource.
     *
     * @see #getResource
     */
    public byte[] getResourceAsBytes (String path)
        throws IOException
    {
        InputStream in = getResource(path);
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte[] buffer = new byte[512];

        // i loathe to while(1), but we need a non-trivial loop condition
        while (true) {
            int bytes = in.read(buffer, 0, buffer.length);
            if (bytes == 0) {
                throw new IOException("Read zero bytes!?");
            } else if (bytes < 0) {
                break;
            }
            out.write(buffer, 0, bytes);
        }

        return out.toByteArray();
    }

    public static void main (String[] args)
    {
        try {
            String root = System.getProperty("root", "");
            URL url = new URL("file:" + root + "/rsrc");
            ResourceManager rmgr = new ResourceManager(url);
            byte[] data = rmgr.getResourceAsBytes("config/miso.properties");
            System.out.println(new String(data));

        } catch (Exception e) {
            e.printStackTrace(System.err);
        }
    }

    protected URL _source;
    protected String _rootPath;
}