ImageIO.java 文件源码

/**
 * Returns an {@code Iterator} containing all currently
 * registered {@code ImageWriter}s that claim to be able to
 * encode the named format.
 *
 * @param formatName a {@code String} containing the informal
 * name of a format (<i>e.g.</i>, "jpeg" or "tiff".
 *
 * @return an {@code Iterator} containing
 * {@code ImageWriter}s.
 *
 * @exception IllegalArgumentException if {@code formatName} is
 * {@code null}.
 *
 * @see javax.imageio.spi.ImageWriterSpi#getFormatNames
 */
public static Iterator<ImageWriter>
    getImageWritersByFormatName(String formatName)
{
    if (formatName == null) {
        throw new IllegalArgumentException("formatName == null!");
    }
    Iterator<ImageWriterSpi> iter;
    // Ensure category is present
    try {
        iter = theRegistry.getServiceProviders(ImageWriterSpi.class,
                                new ContainsFilter(writerFormatNamesMethod,
                                                   formatName),
                                        true);
    } catch (IllegalArgumentException e) {
        return Collections.emptyIterator();
    }
    return new ImageWriterIterator(iter);
}