图片打水印 缩放 以及输入流转换

图片打水印和缩放:

 public final static BufferedImage[] pressImage(InputStream srcImg, String waterImg,float alpha) throws IOException {

    	 //File file = new File(targetImg);
        Image image = ImageIO.read(srcImg);
        int width = image.getWidth(null);
        int height = image.getHeight(null);
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = bufferedImage.createGraphics();
        g.drawImage(image, 0, 0, width, height, null);

        Image waterImage = ImageIO.read(new File(waterImg));    // 水印文件

        int width_1 = waterImage.getWidth(null);
        int height_1 = waterImage.getHeight(null);
        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));

        int div=(int) (0.1*width_1);

        for(int y=0,row=0;y<height;y+=height_1+div,row++)
        {
        	int x=0;

            for(;x<width;x+=width_1+div)
            {
            	g.drawImage(waterImage, x, y, width_1, height_1, null); // 水印文件结束
            }
        }             

        g.dispose();

        BufferedImage bufferedImage2=Thumbnails.of(bufferedImage).size(100, 100).asBufferedImage();

       return new BufferedImage[]{bufferedImage,bufferedImage2};

    }

图片的缩放使用了Thumbnails这个工具,(其实它也可以用来打水印的,不过我还没有研究)

jar 包或者maven 请自行搜索

需要特别注意的是 Thumbnails 默认是按照等比例进行缩放的并且它的缩放规则是:

假设 把图片所放到 200*300

* 若图片横比200小，高比300小，不变

* 若图片横比200小，高比300大，高缩小到300，图片比例不变

* 若图片横比200大，高比300小，横缩小到200，图片比例不变

* 若图片横比200大，高比300大，图片按比例缩小，横为200或高为300

bufferInage转换 inputSteam

private InputStream getInputstreamFromBufferedImage(BufferedImage img) throws IOException{
		 	ByteArrayOutputStream bs =new ByteArrayOutputStream();
		 	ImageOutputStream imOut =ImageIO.createImageOutputStream(bs);
	        ImageIO.write(img,"jpg",imOut); //scaledImage1为BufferedImage，jpg为图像的类型

	        InputStream is =new ByteArrayInputStream(bs.toByteArray());
	        return is;

	}