Base64 编码不起作用

Question

I'm using the following code to encode a java.awt.Image in Base64:

private String asBase64(Image image) throws IOException {
    BufferedImage bufferedImage = new BufferedImage(image.getWidth(null),
            image.getHeight(null), BufferedImage.TYPE_INT_ARGB);
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    ImageIO.write(bufferedImage, "PNG", out);
    byte[] bytes = out.toByteArray();

    return Base64.encodeBytes(bytes);
}

But the returned String is somehow wrong: It seems to be too small (only 308 chars on a 20KB-file) and contains a big amount of repetitive characters in the middle (~200 A chars).

I did some debugging and found out that bufferedImage at least has correct dimensions, but out only contains 308 bytes after executing ImageIO.write(...) . This number increases with bigger images, but the characters keep being repetitive and too few.

Am I missing something?

Answer 1

The code as shown in the question creates an empty BufferedImage , and PNG format encodes empty images pretty effectively.

You probably intended it to contain a copy of the original image:

BufferedImage bufferedImage = new BufferedImage(image.getWidth(null),
        image.getHeight(null), BufferedImage.TYPE_INT_ARGB);
Graphics graphics = bufferedImage.getGraphics();
graphics.drawImage( image, 0, 0, null);
graphics.dispose();