Tanks @StanislavL
在评论中提供了链接（https://community.oracle.com/thread/1264385），这确实很有帮助。有我的解决方案：
File file = new File("gif1.gif");ImageReader reader = ImageIO.getImageReadersBySuffix("GIF").next();ImageInputStream in = ImageIO.createImageInputStream(file);reader.setInput(in);int numImages = reader.getNumImages(true); BufferedImage[] frames = new BufferedImage[pocetObrazku];File fileOut = new File("k.gif");fileOut.createNewFile();ImageWriter iw = ImageIO.getImageWritersByFormatName("gif").next();ImageOutputStream ios = ImageIO.createImageOutputStream(fileOut);iw.setOutput(ios);iw.prepareWriteSequence(null);for (int i = 0; i < numImages ; i++) { BufferedImage image = reader.read(i); frames[i] = reader.read(i); IIOmetadata metadata = reader.getImagemetadata(i); IIOImage ii = new IIOImage(image, null, metadata); iw.writeToSequence(ii, (ImageWriteParam) null); }
