Java原生api实现图片的缩放和打水印操作

TALK IS CHEAP , SHOW THE CODE.

/**
 * @author zhq.xiang
 */
public class PicUtils {
    private static List<String> picFormatList = null;

    static {
        picFormatList = Stream.of("jpg", "png", "gif", "webp", "tiff", "bmp", "jpeg").collect(Collectors.toList());
    }

    /**
     * 按比例压缩图片
     *
     * @param srcPath
     * @param rate
     * @param outputStream
     * @throws Exception
     */
    public static void reduceImg(String srcPath, double rate, OutputStream outputStream) throws Exception {
        InputStreamDto inputStreamDto = FileUtils.read2InputStreamDto(srcPath);
        if (inputStreamDto == null) {
            throw new Exception("获取流参数出错。");
        }
        if (!isPic(inputStreamDto.getFormat())) {
            throw new Exception("文件格式不支持");
        }
        try {
            reduceImg(inputStreamDto.getInputStream(), rate, outputStream);
        } catch (Exception e) {
            e.printStackTrace();
            throw e;
        } finally {
            FileUtils.close(inputStreamDto);
        }
    }

    /**
     * 压缩图片
     *
     * @param inputStream
     * @param rate
     * @param outputStream
     * @throws Exception
     */
    public static void reduceImg(InputStream inputStream, double rate, OutputStream outputStream) throws Exception {
        BufferedImage read = null;
        try {
            read = ImageIO.read(inputStream);
            int widthDist = (int)(read.getWidth() * rate);
            int heightDist = (int)(read.getHeight() * rate);
            // 构造一个类型为预定义图像类型之一的 BufferedImage
            BufferedImage tag = new BufferedImage(widthDist, heightDist, BufferedImage.TYPE_INT_RGB);
            //绘制图像  getScaledInstance表示创建此图像的缩放版本，返回一个新的缩放版本Image,按指定的width,height呈现图像
            //Image.SCALE_SMOOTH,选择图像平滑度比缩放速度具有更高优先级的图像缩放算法。
            tag.getGraphics().drawImage(read.getScaledInstance(widthDist, heightDist, Image.SCALE_SMOOTH), 0, 0, null);
            JPEGImageEncoder jpegEncoder = JPEGCodec.createJPEGEncoder(outputStream);
            jpegEncoder.encode(tag);
        } catch (IOException e) {
            e.printStackTrace();
            throw e;
        }
    }

    /**
     * 按比例进行缩放图片
     *
     * @param srcPath  原图地址url
     * @param rate     缩放比例
     * @param distPath 目标路径
     * @return
     */
    public static void reduceImg(String srcPath, double rate, String distPath) throws Exception {
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(distPath);
            reduceImg(srcPath, rate, fos);
        } catch (Exception e) {
            e.printStackTrace();
            throw e;
        } finally {
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 给图片打上文字水印
     * @param logoText log文字
     * @param inputStream
     * @param outputStream
     * @param degree 旋转角度
     * @param color 颜色
     * @param format 图片后缀
     * @param fontSize 字体大小
     * @param alpha 透明度
     * @param startIndexPer x轴的起始位置，相对宽度的百分比数
     * @param endIndexPer y轴的起始位置，相对高度的百分比数
     */
    public static void markImageByText(String logoText, InputStream inputStream, OutputStream outputStream,
        Integer degree, Color color, String format,int fontSize,float alpha,float startIndexPer,float endIndexPer) {
        try {
            Image srcImg = ImageIO.read(inputStream);
            BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null), srcImg.getHeight(null),
                BufferedImage.TYPE_INT_RGB);
            // 2、得到画笔对象
            Graphics2D g = buffImg.createGraphics();
            // 3、设置对线段的锯齿状边缘处理
            g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g.drawImage(
                srcImg.getScaledInstance(srcImg.getWidth(null), srcImg.getHeight(null), java.awt.Image.SCALE_SMOOTH), 0,
                0, null);
            // 4、设置水印旋转
            if (null != degree) {
                g.rotate(Math.toRadians(degree),  buffImg.getWidth()/2,buffImg.getHeight() /2);
            }
            // 5、设置水印文字颜色
            g.setColor(color);
            if(fontSize > (buffImg.getHeight()/2)){
                fontSize = buffImg.getHeight()/2;
            }
            // 6、设置水印文字Font
            g.setFont(new java.awt.Font("宋体", java.awt.Font.BOLD, fontSize));
            // 7、设置水印文字透明度
            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));
            // 8、第一参数->设置的内容，后面两个参数->文字在图片上的座标位置(x,y)
            if(startIndexPer > 1.0f){
                startIndexPer = 1.0f;
            }
            if(endIndexPer > 1.0f){
                endIndexPer = 1.0f;
            }
            g.drawString(logoText,  startIndexPer*buffImg.getWidth() , endIndexPer*buffImg.getHeight());

            // 9、释放资源
            g.dispose();
            // 10、生成图片
            ImageIO.write(buffImg, format, outputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
    /**
     * 图片能否压缩
     *
     * @param format
     * @return
     */
    private static boolean isPic(String format) {
        return picFormatList.contains(format);
    }
}