cpfile.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.impl.io.CPFile

   Copyright 2004 The Apache Software Foundation or its licensors, as applicable.

   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.apache.derby.impl.io;

import org.apache.derby.io.StorageFile;

import java.io.InputStream;

import java.io.FileNotFoundException;

/**
 * This class provides a class path based implementation of the StorageFile interface. It is used by the
 * database engine to access persistent data and transaction logs under the classpath subsubprotocol.
 */
class CPFile extends InputStreamFile
{

    private final CPStorageFactory storageFactory;
 
    CPFile( CPStorageFactory storageFactory, String path)
    {
        super( storageFactory, path);
        this.storageFactory = storageFactory;
    }

    CPFile( CPStorageFactory storageFactory, String parent, String name)
    {
        super( storageFactory, parent, name);
        this.storageFactory = storageFactory;
    }

    CPFile( CPFile dir, String name)
    {
        super( dir,name);
        this.storageFactory = dir.storageFactory;
    }

    private CPFile( CPStorageFactory storageFactory, String child, int pathLen)
    {
        super( storageFactory, child, pathLen);
        this.storageFactory = storageFactory;
    }

    /**
     * Tests whether the named file exists.
     *
     * @return <b>true</b> if the named file exists, <b>false</b> if not.
     */
    public boolean exists()
    {
    	ClassLoader cl = Thread.currentThread().getContextClassLoader();
    	if (cl != null)
    		if (cl.getResource(path) != null)
    			return true;
    	// don't assume the context class loader is tied
    	// into the class loader that loaded this class.
    	cl = getClass().getClassLoader();
		// Javadoc indicates implementations can use
		// null as a return from Class.getClassLoader()
		// to indicate the system/bootstrap classloader.
    	if (cl != null)
    	{
    		return (cl.getResource(path) != null);
    	}
    	else
    	{
    		return ClassLoader.getSystemResource(path) != null;
    	}
    } // end of exists

    /**
     * Get the parent of this file.
     *
     * @param pathLen the length of the parent's path name.
     */
    StorageFile getParentDir( int pathLen)
    {
        return new CPFile( storageFactory, path, pathLen);
    }
    
    /**
     * Creates an input stream from a file name.
     *
     * @return an input stream suitable for reading from the file.
     *
     * @exception FileNotFoundException if the file is not found.
     */
    public InputStream getInputStream( ) throws FileNotFoundException
    {
    	//System.out.println("HERE FOR " + toString());
    	InputStream is = null;
    	ClassLoader cl = Thread.currentThread().getContextClassLoader();
    	if (cl != null)
    		is = cl.getResourceAsStream(path);
    	
       	// don't assume the context class loader is tied
    	// into the class loader that loaded this class.
    	if (is == null)
    	{
    		cl = getClass().getClassLoader();
    		// Javadoc indicates implementations can use
    		// null as a return from Class.getClassLoader()
    		// to indicate the system/bootstrap classloader.
    		if (cl != null)
    			is = cl.getResourceAsStream(path);
    		else
    			is = ClassLoader.getSystemResourceAsStream(path);
    	}
    	
    	if (is == null)
    		throw new FileNotFoundException(toString());
    	return is;
    	
    } // end of getInputStream
}