How to convert BufferedImage to InputStream?

Question

I am uploading images using servlet. To perform resize operations i am converting InputStream to BufferedImage. Now i want to save it in mongoDB. Since, i am new to mongoDB as far as i know, GridFS takes InputStream.

So, is there any way to convert BufferedImage to InputStream?

Solution 1

You need to save the BufferedImage to a ByteArrayOutputStream using the ImageIO class, then create a ByteArrayInputStream from toByteArray().

Solution 2

BufferedImage ➙ ByteArrayOutputStream ➙ byte[] ➙ ByteArrayInputStream

Use the ImageIO.write method to make a BufferedImage (which is a RenderedImage) into a ByteArrayOutputStream. From there get a byte array (byte[]), feeding that into an InputStream of type ByteArrayInputStream.

ByteArrayOutputStream os = new ByteArrayOutputStream();
ImageIO.write(buffImage, "jpeg", os);                          // Passing: ​(RenderedImage im, String formatName, OutputStream output)
InputStream is = new ByteArrayInputStream(os.toByteArray());

Both the ByteArrayOutputStream and InputStream implement AutoCloseable. So you can conveniently have those closed automatically by using try-with-resources syntax.

Solution 3

First of all you must get your "bytes":

byte[] buffer = ((DataBufferByte)(bufferedImage).getRaster().getDataBuffer()).getData();

And then use ByteArrayInputStream(byte[] buf) constructor to create your InputStream;

Solution 4

By overriding the method toByteArray(), returning the buf itself (not copying), you can avoid memory related problems. This will share the same array, and not creating another of the correct size. The important thing is to use the size() method in order to control the number of valid bytes into the array.

final ByteArrayOutputStream output = new ByteArrayOutputStream() {
    @Override
    public synchronized byte[] toByteArray() {
        return this.buf;
    }
};
ImageIO.write(image, "png", output);
return new ByteArrayInputStream(output.toByteArray(), 0, output.size());

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Comments

[djechlin]

Why is this necessary? Doesn't this load an extra (large) byte array into memory?

[Möoz]

Tried this, got a compile error on the third line: "The method ByteArrayInputStream(byte[]) is undefined for the type" What does that mean?

[Sorter]

Have you made the import correctly. The constructor is correct. docs.oracle.com/javase/7/docs/api/java/io/…

[morpheus]

+1. and this method copies the data not once but twice! once when writing to ByteArrayOutputStream and then again by converting it into a byte array when toByteArray() is called.

[Nicofisi]

Doesn't anything need to be closed anywhere? I'm not asking to be mean, I simply dont know ;)

[Sorter]

Let your IDE do that for you.

[Sorter]

You can find the code below

[Basil Bourque]

@Nicofisi Both ByteArrayOutputStream & InputStream implement AutoCloseable. So you can use try-with-resources syntax to conveniently and automatically close those resources whether or not exceptions are thrown.

[Nikita Kobtsev]

It's funny that this code snippet works much more efficiently than the approved one, although not as elegant

[Nikita Kobtsev]

But it is worth noting that this will only work with images where byte[] is used to represent each pixel