java图片基本操作-缩放，旋转，镜像，拼接

/**
     * 缩放
     */
    public static void zoomByScale(BufferedImage bufImage, double scale) throws IOException {
        //获取缩放后的长和宽
        int _width = (int) (scale * bufImage.getWidth());
        int _height = (int) (scale * bufImage.getHeight());
        //获取缩放后的Image对象
        Image _img = bufImage.getScaledInstance(_width, _height, Image.SCALE_DEFAULT);
        //新建一个和Image对象相同大小的画布
        BufferedImage image = new BufferedImage(_width, _height, BufferedImage.TYPE_INT_RGB);
        //获取画笔
        Graphics2D graphics = image.createGraphics();
        //将Image对象画在画布上,最后一个参数,ImageObserver:接收有关 Image 信息通知的异步更新接口,没用到直接传空
        graphics.drawImage(_img, 0, 0, null);
        //释放资源
        graphics.dispose();
        //使用ImageIO的方法进行输出,记得关闭资源
        OutputStream out = new FileOutputStream("/Users/sunxianyan/Downloads/缩放.jpg");
        ImageIO.write(image, "jpeg", out);
        out.close();
    }

    /**
     * 旋转
     */
    public static void rotate(BufferedImage bufImage, int degree) throws IOException {
        int w = bufImage.getWidth();// 得到图片宽度。
        int h = bufImage.getHeight();// 得到图片高度。

        int swidth = 0; //旋转后的宽度
        int sheight = 0;//旋转后的高度
        int x;//原点横坐标
        int y;//原点纵坐标

        degree = degree %360;
        if (degree<0){
            degree = 360+degree;
        }
        double theta = Math.toRadians(degree);
        if (degree == 180|| degree ==0||degree==360){
            sheight = bufImage.getWidth();
            swidth =bufImage.getHeight();
        } else if (degree == 90 || degree == 270) {
            sheight = bufImage.getWidth();
            swidth = bufImage.getHeight();
        } else {
            swidth = (int) (Math.sqrt(w * w + h * h));
            sheight = (int) (Math.sqrt(w * w + h * h));
        }
        x = (swidth / 2) - (w / 2);// 确定原点坐标
        y = (sheight / 2) - (h / 2);
        BufferedImage spinImage = new BufferedImage(swidth, sheight,bufImage.getType());
        // 设置图片背景颜色
        Graphics2D gs = (Graphics2D) spinImage.getGraphics();
        gs.setColor(Color.white);
        gs.fillRect(0, 0, swidth, sheight);// 以给定颜色绘制旋转后图片的背景

        AffineTransform at = new AffineTransform();
        at.rotate(theta, swidth / 2, sheight / 2);// 旋转图象
        at.translate(x, y);
        AffineTransformOp op = new AffineTransformOp(at,
                AffineTransformOp.TYPE_BICUBIC);
        spinImage = op.filter(bufImage, spinImage);
        ImageIO.write(spinImage,"jpeg", new File("/Users/sunxianyan/Downloads/旋转.jpg"));
    }

    /**
     * 裁剪
     */
    public static void clip(BufferedImage bufImage) throws IOException {
        ImageIO.write(bufImage.getSubimage(0, 0, 100, 100), "JPEG", new File("/Users/sunxianyan/Downloads/裁剪.jpg"));
    }

    /**
     * 镜像
     */
    public static void mirror(BufferedImage bufImage) throws IOException {

        // 获取图片的宽高
        final int width = bufImage.getWidth();
        final int height = bufImage.getHeight();

        // 读取出图片的所有像素
        int[] rgbs = bufImage.getRGB(0, 0, width, height, null, 0, width);

        // 对图片的像素矩阵进行水平镜像
        for (int row = 0; row < height; row++) {
            for (int col = 0; col < width / 2; col++) {
                int temp = rgbs[row * width + col];
                rgbs[row * width + col] = rgbs[row * width + (width - 1 - col)];
                rgbs[row * width + (width - 1 - col)] = temp;
            }
        }

        // 把水平镜像后的像素矩阵设置回 bufImage
        bufImage.setRGB(0, 0, width, height, rgbs, 0, width);
        ImageIO.write(bufImage, "JPEG", new File("/Users/sunxianyan/Downloads/镜像.jpg"));
    }

    /**
     * 拼接
     */
    public static void add() throws IOException {
        String fileUrl = "https://static.cdn.longmaosoft.com/00039447dd4fa068e1835148c3d5431e.png";
        String filepath = "/Users/sunxianyan/Downloads/223233fmbmgbxrmfwmi3mw.jpg";

        BufferedImage bufImage = ImageIO.read(new URL(fileUrl));
        BufferedImage addImage = ImageIO.read(new File(filepath));

        Graphics2D g2d = (Graphics2D) bufImage.getGraphics().create();

        // 绘制图片（如果宽高传的不是图片原本的宽高, 则图片将会适当缩放绘制）
        g2d.drawImage(addImage, 50, 50, addImage.getWidth(), addImage.getHeight(),null);

        g2d.dispose();

        ImageIO.write(bufImage,"jpeg", new File("/Users/sunxianyan/Downloads/拼接.jpg"));
    }