[src: https://blog.idrsolutions.com/2012/05/replacing-the-deprecated-java-jpeg-classes-for-java-7/]
In the early days of Java, Sun produced a really handy set of classes to handle JPEG images. These included some really nifty little features like the ability to easily set the amount of compression and the resolution. When ImageIO came along, the class was deprecated. This means that it is still in Java but not guaranteed to be in any later releases. ImageIO was more complicated to use for JPEG images and we felt the earlier code produced better results so we continued to use it.
I have been checking our code against the new Java 7 (release 4) build for the Mac and it now appears that the old JPEG classes have finally been removed. So I have updated my code to use ImageIO. Here is my updated version with both old and new versions so you can see the changes if you are still using these classes.
public static void saveAsJPEG(String jpgFlag,BufferedImage image_to_save, float JPEGcompression, FileOutputStream fos) throws IOException {
//useful documentation at http://docs.oracle.com/javase/7/docs/api/javax/imageio/metadata/doc-files/jpeg_metadata.html
//useful example program at http://johnbokma.com/java/obtaining-image-metadata.html to output JPEG data
//old jpeg class
//com.sun.image.codec.jpeg.JPEGImageEncoder jpegEncoder = com.sun.image.codec.jpeg.JPEGCodec.createJPEGEncoder(fos);
//com.sun.image.codec.jpeg.JPEGEncodeParam jpegEncodeParam = jpegEncoder.getDefaultJPEGEncodeParam(image_to_save);
// Image writer
JPEGImageWriter imageWriter = (JPEGImageWriter) ImageIO.getImageWritersBySuffix(“jpeg”).next();
ImageOutputStream ios = ImageIO.createImageOutputStream(fos);
imageWriter.setOutput(ios);
//and metadata
IIOMetadata imageMetaData = imageWriter.getDefaultImageMetadata(new ImageTypeSpecifier(image_to_save), null);
if (jpgFlag != null){
int dpi = 96;
try {
dpi = Integer.parseInt(jpgFlag);
} catch (Exception e) {
e.printStackTrace();
}
//old metadata
//jpegEncodeParam.setDensityUnit(com.sun.image.codec.jpeg.JPEGEncodeParam.DENSITY_UNIT_DOTS_INCH);
//jpegEncodeParam.setXDensity(dpi);
//jpegEncodeParam.setYDensity(dpi);
//new metadata
Element tree = (Element) imageMetaData.getAsTree(“javax_imageio_jpeg_image_1.0?);
Element jfif = (Element)tree.getElementsByTagName(“app0JFIF”).item(0);
jfif.setAttribute(“Xdensity”, Integer.toString(dpi));
jfif.setAttribute(“Ydensity”, Integer.toString(dpi));
}
if(JPEGcompression>=0 && JPEGcompression<=1f){
//old compression
//jpegEncodeParam.setQuality(JPEGcompression,false);
// new Compression
JPEGImageWriteParam jpegParams = (JPEGImageWriteParam) imageWriter.getDefaultWriteParam();
jpegParams.setCompressionMode(JPEGImageWriteParam.MODE_EXPLICIT);
jpegParams.setCompressionQuality(JPEGcompression);
}
//old write and clean
//jpegEncoder.encode(image_to_save, jpegEncodeParam);
//new Write and clean up
imageWriter.write(imageMetaData, new IIOImage(image_to_save, null, null), null);
ios.close();
imageWriter.dispose();
}
Otherwise, Java 7 looks to be a definite progression over Java 6. What do you think of it?
Replacing the deprecated Java JPEG classes for Java 7
原文：http://www.cnblogs.com/sanshizi/p/4590618.html