URLResource.java

// ========================================================================
// Copyright 1996-2005 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at 
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ========================================================================
package org.mortbay.resource;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.security.Permission;

import org.mortbay.log.Log;
import org.mortbay.util.URIUtil;

/* ------------------------------------------------------------ */
/** Abstract resource class.
 *
 * @author Nuno Pregui�a
 * @author Greg Wilkins (gregw)
 */
public class URLResource extends Resource
{

    
    protected URL _url;
    protected String _urlString;
    protected transient URLConnection _connection;
    protected transient InputStream _in=null;
    transient boolean _useCaches = Resource.__defaultUseCaches;
    
    /* ------------------------------------------------------------ */
    protected URLResource(URL url, URLConnection connection)
    {
        _url = url;
        _urlString=_url.toString();
        _connection=connection;
    }
    
    protected URLResource (URL url, URLConnection connection, boolean useCaches)
    {
        this (url, connection);
        _useCaches = useCaches;
    }

    /* ------------------------------------------------------------ */
    protected synchronized boolean checkConnection()
    {
        if (_connection==null)
        {
            try{
                _connection=_url.openConnection();
                _connection.setUseCaches(_useCaches);
            }
            catch(IOException e)
            {
                Log.ignore(e);
            }
        }
        return _connection!=null;
    }

    /* ------------------------------------------------------------ */
    /** Release any resources held by the resource.
     */
    public synchronized void release()
    {
        if (_in!=null)
        {
            try{_in.close();}catch(IOException e){Log.ignore(e);}
            _in=null;
        }

        if (_connection!=null)
            _connection=null;
    }

    /* ------------------------------------------------------------ */
    /**
     * Returns true if the respresened resource exists.
     */
    public boolean exists()
    {
        try
        {
            synchronized(this)
            {
                if (checkConnection() && _in==null )
                    _in = _connection.getInputStream();
            }
        }
        catch (IOException e)
        {
            Log.ignore(e);
        }
        return _in!=null;
    }

    /* ------------------------------------------------------------ */
    /**
     * Returns true if the respresenetd resource is a container/directory.
     * If the resource is not a file, resources ending with "/" are
     * considered directories.
     */
    public boolean isDirectory()
    {
        return exists() && _url.toString().endsWith("/");
    }


    /* ------------------------------------------------------------ */
    /**
     * Returns the last modified time
     */
    public long lastModified()
    {
        if (checkConnection())
            return _connection.getLastModified();
        return -1;
    }


    /* ------------------------------------------------------------ */
    /**
     * Return the length of the resource
     */
    public long length()
    {
        if (checkConnection())
            return _connection.getContentLength();
        return -1;
    }

    /* ------------------------------------------------------------ */
    /**
     * Returns an URL representing the given resource
     */
    public URL getURL()
    {
        return _url;
    }

    /* ------------------------------------------------------------ */
    /**
     * Returns an File representing the given resource or NULL if this
     * is not possible.
     */
    public File getFile()
        throws IOException
    {
        // Try the permission hack
        if (checkConnection())
        {
            Permission perm = _connection.getPermission();
            if (perm instanceof java.io.FilePermission)
                return new File(perm.getName());
        }

        // Try the URL file arg
        try {return new File(_url.getFile());}
        catch(Exception e) {Log.ignore(e);}

        // Don't know the file
        return null;    
    }

    /* ------------------------------------------------------------ */
    /**
     * Returns the name of the resource
     */
    public String getName()
    {
        return _url.toExternalForm();
    }

    /* ------------------------------------------------------------ */
    /**
     * Returns an input stream to the resource
     */
    public synchronized InputStream getInputStream()
        throws java.io.IOException
    {
        if (!checkConnection())
            throw new IOException( "Invalid resource");

        try
        {    
            if( _in != null)
            {
                InputStream in = _in;
                _in=null;
                return in;
            }
            return _connection.getInputStream();
        }
        finally
        {
            _connection=null;
        }
    }


    /* ------------------------------------------------------------ */
    /**
     * Returns an output stream to the resource
     */
    public OutputStream getOutputStream()
        throws java.io.IOException, SecurityException
    {
        throw new IOException( "Output not supported");
    }

    /* ------------------------------------------------------------ */
    /**
     * Deletes the given resource
     */
    public boolean delete()
        throws SecurityException
    {
        throw new SecurityException( "Delete not supported");
    }

    /* ------------------------------------------------------------ */
    /**
     * Rename the given resource
     */
    public boolean renameTo( Resource dest)
        throws SecurityException
    {
        throw new SecurityException( "RenameTo not supported");
    }

    /* ------------------------------------------------------------ */
    /**
     * Returns a list of resource names contained in the given resource
     */
    public String[] list()
    {
        return null;
    }

    /* ------------------------------------------------------------ */
    /**
     * Returns the resource contained inside the current resource with the
     * given name
     */
    public Resource addPath(String path)
        throws IOException,MalformedURLException
    {
        if (path==null)
            return null;

        path = URIUtil.canonicalPath(path);

        return newResource(URIUtil.addPaths(_url.toExternalForm(),path));
    }

    /* ------------------------------------------------------------ */
    public String toString()
    {
        return _urlString;
    }

    /* ------------------------------------------------------------ */
    public int hashCode()
    {
        return _url.hashCode();
    }
    
    /* ------------------------------------------------------------ */
    public boolean equals( Object o)
    {
        return o instanceof URLResource &&
            _url.equals(((URLResource)o)._url);
    }

    public boolean getUseCaches ()
    {
        return _useCaches;
    }
}