java旋转base64位，自定义旋转角度角度

╰半橙微兮° 2024-04-07 10:29 112阅读 0赞

## base64图片互转在线网站 ##

[https://imgtobase64.d777.com/][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);
    	}
    }

## 旋转前 ##

![在这里插入图片描述][df9f1ef082b44f15993852bc709e10b5.png]

## 旋转后 ##

![在这里插入图片描述][9e216e2a948b46c5839996f0ab9e0e9b.png]

[https_imgtobase64.d777.com]: https://imgtobase64.d777.com/
[df9f1ef082b44f15993852bc709e10b5.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/a7a9a51b747e4b838dd3db8ecb5d75ac.png
[9e216e2a948b46c5839996f0ab9e0e9b.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/a9b3750a251f4f208f88b348d7d85f2f.png