Bug 173582 Run servlet should not be affected by values in document.[0000]
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
* @return
	 */
	public static String getImageTempFolder( HttpServletRequest request )
	{
		String tempFolder = imageFolder;
		
		String sessionId = request.getSession( ).getId( );
		if ( sessionId != null )
			tempFolder = tempFolder + File.separator + sessionId;
		return tempFolder;
	}
	/**
	 * Clear the temp files when session is expired
	 * 
	 * @param sessionId
	 */
	public static void clearSessionFiles( String sessionId )
	{
		if ( sessionId == null )
			return;
		
		String tempFolder = documentFolder + File.separator + sessionId;
		File file = new File( tempFolder );
		deleteDir( file );
		
		tempFolder = imageFolder + File.separator + sessionId;
		file = new File( tempFolder );
		deleteDir( file );
	}
}