@Override
    public void setRootPath(String rootPath) {
        if (rootPath == null) {
            throw new IllegalArgumentException("rootPath cannot be null");
        }
        
        try {
            root = new File(rootPath).getCanonicalFile();
            if (!root.isDirectory()){
                throw new IllegalArgumentException("Given root path \"" + root + "\" is not a directory");
            }
        } catch (IOException ex) {
            throw new AssetLoadException("Root path is invalid", ex);
        }
    }
<code>FileLocator</code> allows you to specify a folder where to
look for assets. 

@author Kirill Vainer
jme3-core/src/plugins/java/com/jme3/asset/plugins/FileLocator.java