java旋转base64位，自定义旋转角度角度

base64图片互转在线网站

https://imgtobase64.d777.com/

工具类

public final class Base64ImageUtil {


	private static BufferedImage rotate(Image src, int angel) {
		int src_width = src.getWidth(null);
		int src_height = src.getHeight(null);
		// calculate the new image size
		Rectangle rect_des = CalcRotatedSize(new Rectangle(new Dimension(
			src_width, src_height)), angel);

		BufferedImage res = null;
		res = new BufferedImage(rect_des.width, rect_des.height,
			BufferedImage.TYPE_INT_RGB);
		Graphics2D g2 = res.createGraphics();
		res = g2.getDeviceConfiguration().createCompatibleImage(rect_des.width, rect_des.height, Transparency.TRANSLUCENT);
		g2.dispose();
		g2 = res.createGraphics();
		// transform
		g2.translate((rect_des.width - src_width) / 2,
			(rect_des.height - src_height) / 2);
		g2.rotate(Math.toRadians(angel), src_width / 2, src_height / 2);
		g2.setColor(new Color(255, 0, 0));
		g2.setStroke(new BasicStroke(1));
		g2.drawImage(src, null, null);
		g2.dispose();
		return res;
	}

	public static Rectangle CalcRotatedSize(Rectangle src, int angel) {
		// if angel is greater than 90 degree, we need to do some conversion
		if (angel >= 90) {
			if (angel / 90 % 2 == 1) {
				int temp = src.height;
				src.height = src.width;
				src.width = temp;
			}
			angel = angel % 90;
		}

		double r = Math.sqrt(src.height * src.height + src.width * src.width) / 2;
		double len = 2 * Math.sin(Math.toRadians(angel) / 2) * r;
		double angel_alpha = (Math.PI - Math.toRadians(angel)) / 2;
		double angel_dalta_width = Math.atan((double) src.height / src.width);
		double angel_dalta_height = Math.atan((double) src.width / src.height);

		int len_dalta_width = (int) (len * Math.cos(Math.PI - angel_alpha
			- angel_dalta_width));
		int len_dalta_height = (int) (len * Math.cos(Math.PI - angel_alpha
			- angel_dalta_height));
		int des_width = src.width + len_dalta_width * 2;
		int des_height = src.height + len_dalta_height * 2;
		return new Rectangle(new Dimension(des_width, des_height));
	}

	/**
	 * 顺时针旋转
	 *
	 * @param base64FileStr
	 * @param rotate
	 * @return
	 * @throws IOException
	 */
	public static String rotateImage(String base64FileStr, int rotate) throws IOException {
		if (StringUtils.isEmpty(base64FileStr)) {
			return "";
		}

		Base64.Decoder decoder = Base64.getDecoder();
		// Base64解码,对字节数组字符串进行Base64解码并生成文件
		final byte[] byt = decoder.decode(base64FileStr);
		for (int i = 0, len = byt.length; i < len; ++i) {
			// 调整异常数据
			if (byt[i] < 0) {
				byt[i] += 256;
			}
		}
		InputStream input = new ByteArrayInputStream(byt);
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		BufferedImage src = ImageIO.read(input);
		BufferedImage des = rotate(src, rotate);
		ImageIO.write(des, "png", out);
		final Base64.Encoder encoder = Base64.getEncoder();
		final byte[] bytes = out.toByteArray();
		return encoder.encodeToString(bytes);
	}


	public static void main(String[] args) throws IOException {
		String base64FileStr = "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";
		final String image = rotateImage(base64FileStr, 90);
		System.out.println("data:image/png;base64,"+image);
	}
}
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旋转前

旋转后