java - 在不删除其 EXIF 数据的情况下处理图像

Question

使用 imageIO，我通常会遇到转换图像文件的问题，在覆盖它之后，它会丢失所有的 EXIF 数据。有没有什么方法可以在不先提取、缓存然后重置的情况下保留它？

Answer 1

ImageIO 本身确实具有此功能，但您需要使用 ImageReader 而不是 ImageIO.read:

ImageReader reader = ImageIO.getImageReadersBySuffix("jpg").next();

(您可能还想检查这样的阅读器是否存在)。 然后你需要设置输入:

reader.setInput(ImageIO.createImageInputStream(your_imput_stream));

现在您可以保存您的元数据:

IIOMetadata metadata = reader.getImageMetadata(0); 
                            // As far as I understand you should provide 
                            // index as tiff images could have multiple pages

然后读取图像:

BufferedImage bi = reader.read(0);

当你想保存新图片时，你应该使用ImageWriter:

// I'm writing to byte array in memory, but you may use any other stream
ByteArrayOutputStream os = new ByteArrayOutputStream(255);
ImageOutputStream ios = ImageIO.createImageOutputStream(os);

Iterator<ImageWriter> iter = ImageIO.getImageWritersByFormatName("jpeg");
ImageWriter writer = iter.next();
writer.setOutput(ios);

//You may want also to alter jpeg quality
ImageWriteParam iwParam = writer.getDefaultWriteParam();
iwParam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
iwParam.setCompressionQuality(.95f);

//Note: we're using metadata we've already saved.
writer.write(null, new IIOImage(bi, null, metadata), iwParam);
writer.dispose();

//ImageIO.write(bi, "jpg", ios); <- This was initially in the code but actually it was only adding image again at the end of the file.

因为这是一个老话题，我想这个答案有点太晚了，但可能会对其他人有所帮助，因为这个话题仍然可以在谷歌上搜索。