java.io.Image 到 InputStream

Question

我正在调整图像大小，我需要返回一个 InputStream 对象

public InputStream resize(InputStream input, int maxSize){
   BufferedImage image = ImageIO.read(input);
   double scale = (double) image.getWidth()/maxSize;
   Image scaledImage = image.getScaledInstance( (int) (image.getWidth() * scale), (int) (image.getHeight() * scale), Image.SCALE_SMOOTH);
   InputStream ret = (InputStream) scaledImage;//this is wrong cast
   retrun ret;
}

如何将图像转换为 InputStream？

Answer 1

您可以使用此代码进行转换：

 BufferedImage bufferedImage = new BufferedImage(image.getWidth(null), image.getHeight(null),    BufferedImage.TYPE_INT_RGB);
//bufferedImage is the RenderedImage to be written
Graphics2D g2 = bufferedImage.createGraphics();
g2.drawImage(image, null, null);

ByteArrayOutputStream outStream = new ByteArrayOutputStream();
ImageIO.write(bufferedImage, "jpg", outStream); 
InputStream is = new ByteArrayInputStream(outStream.toByteArray());