创建具有Retina支持的BufferedImage

Question

我正在使用最新的JDK 7u45进行开发。当我创建一个用于生成验证码的简单servlet时，我发现图像相当模糊。图像看起来像这样：

我的Macbook pro视网膜显示器的图像质量很差，看起来很差。 我用来创建BufferedImage的代码非常简单：

    public static BufferedImage getImage() {
        BufferedImage image = new BufferedImage(IMAGE_WIDTH,IMAGE_HEIGHT,BufferedImage.TYPE_INT_RGB);
        Graphics graphics = image.getGraphics();
        drawRandomNumber((Graphics2D)graphics);

        return image;
    }

    private static void drawRandomNumber(Graphics2D graphics) {
        graphics.setColor(Color.RED);
        graphics.setFont(new Font("Arial",Font.BOLD|Font.ITALIC,RANDOM_NUMBER_FONT_SIZE));
        char lch = 'a',hch = 'z';
        char lcach = 'A',hcach = 'Z';
        int x = RANDOM_NUMBER_START_X;
        for (int i = 0;i < RANDOM_NUMBER_NUM;i++) {
            char ch = new Random().nextBoolean() ?
                    (char)(new Random().nextInt(hch - lch) + lch) :
                    (char)(new Random().nextInt(hcach - lcach) + lcach);

            int degree = new Random().nextInt() % 30;
            graphics.rotate(degree * Math.PI / 180,x,RANDOM_NUMBER_START_Y);
            graphics.drawString(ch + "",x,RANDOM_NUMBER_START_Y);
            graphics.rotate(-degree * Math.PI / 180,x,RANDOM_NUMBER_START_Y);
            x += 60;
        }
    }

将图像写入servlet的代码：

ImageIO.write(image, "png", response.getOutputStream());

我只是想知道如果我想创建一个支持HDPI显示的高质量图像，我该怎么办？有没有办法用java代码生成高质量的图像？我尝试了很多方法，但它们似乎没什么帮助

Answer 1

private float xScaleFactor, yScaleFactor = ...;
    private BufferedImage originalImage = ...;

    public void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D)g;
        int newW = (int)(originalImage.getWidth() * xScaleFactor);
        int newH = (int)(originalImage.getHeight() * yScaleFactor);
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                            RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g2.drawImage(originalImage, 0, 0, newW, newH, null);
    }