Compress image without saving it — in Java

问题

Is there a way, in Java, to compute what the size of a compressed image will be w/o saving the image? (This will be used to determine the quality necessary to compress an image to a specific size.)

Something like this, but in Java instead of C#, and where the Stream can be a dead end.

回答1:

Here's a simple implementation.

public class LengthCounterOutputStream extends OutputStream{

    private int byteCounter = 0;

    @Override
    public void write(int b){
        byteCounter++;
    }

    @Override
    public void write(@NotNull byte[] b){
        this.write(b, 0, b.length);
    }

    @Override
    public void write(@NotNull byte[] b, int off, int len){
        byteCounter += len;
    }

    public int getByteCounter(){
        return byteCounter;
    }
}

来源：https://stackoverflow.com/questions/56870530/compress-image-without-saving-it-in-java