基于Java和Spring：实现图片压缩、WebP格式转换与水印添加

<!-- https://mvnrepository.com/artifact/org.sejda.imageio/webp-imageio -->
<dependency>
    <groupId>org.sejda.imageio</groupId>
    <artifactId>webp-imageio</artifactId>
    <version>0.1.6</version>
</dependency>

/**
 * Author:      微信公众号：种棵代码技术树
 * Date:        2024/2/24
 * Description: webp-imageio 处理图片
 * Version: 1.0
 */
public class PicWebPTest {
	public static void main(String[] args) throws IOException {
		LocalDateTime startTime = LocalDateTime.now();
        //添加图片水印
		addPictureWatermarkAndConvert("your_master_picture_path",
                                      "your_output_picture_path",
                        			  "your_water_image_path");

        //添加文字水印
		addWatermarkAndConvert("your_master_picture_path", 
                               "your_output_picture_path",
                               "种棵代码技术树");

        //计算压缩率
		double compressionRatio = calculateCompressionRatio("your_master_picture_path",
				"your_output_picture_path");
		LocalDateTime endTime = LocalDateTime.now();
		Duration duration = Duration.between(startTime, endTime);
		long secondsDifference = Math.abs(duration.getSeconds());
		System.out.println("Time: " + secondsDifference + "s");
		System.out.println("Compression ratio: " + compressionRatio + "%");
	}

	/**
	 * 添加图片水印
	 *
	 * @param input              原图位置
	 * @param output             输出图片位置
	 * @param watermarkImagePath 水印图片位置
	 * @throws IOException IO异常
	 */
	public static void addPictureWatermarkAndConvert(String input, String output, String watermarkImagePath) throws IOException {
		// 读取原始图片
		File inputFile = new File(input);
		BufferedImage image = ImageIO.read(inputFile);

		// 创建一个带有水印的新图片
		BufferedImage watermarkedImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);
		Graphics2D graphics = watermarkedImage.createGraphics();
		graphics.drawImage(image, 0, 0, null);

		// 加载水印图片
		File watermarkFile = new File(watermarkImagePath);
		BufferedImage watermarkImage = ImageIO.read(watermarkFile);

		// 计算水印图片的大小，使其适应原图大小
		int watermarkWidth = (int) (image.getWidth() * 0.125); 
		int watermarkHeight = watermarkWidth * watermarkImage.getHeight() / watermarkImage.getWidth();
		BufferedImage scaledWatermarkImage = new BufferedImage(watermarkWidth, watermarkHeight, BufferedImage.TYPE_INT_ARGB);
		Graphics2D watermarkGraphics = scaledWatermarkImage.createGraphics();
		watermarkGraphics.drawImage(watermarkImage, 0, 0, watermarkWidth, watermarkHeight, null);
		watermarkGraphics.dispose();

		// 设置水印位置
		int x = watermarkedImage.getWidth() - watermarkWidth - 10;
		int y = watermarkedImage.getHeight() - watermarkHeight - 10;

		// 添加水印
		graphics.drawImage(scaledWatermarkImage, x, y, null);

		// 输出带有水印的图片
		File outputFile = new File(output);
		ImageIO.write(watermarkedImage, "webp", outputFile);

		// 释放资源
		graphics.dispose();
	}


	/**
	 * 给图片添加文字水印
	 *
	 * @param originInput         原图地址
	 * @param output        处理后的图片位置
	 * @param watermarkText 水印文字
	 * @throws IOException IO异常
	 */
	public static void addWatermarkAndConvert(String originInput, String output, String watermarkText) throws IOException {
		// 读取原始图片
		File inputFile = new File(originInput);
		BufferedImage image = ImageIO.read(inputFile);

		// 创建一个带有水印的新图片
		BufferedImage watermarkedImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);
		Graphics2D graphics = watermarkedImage.createGraphics();
		graphics.drawImage(image, 0, 0, null);

		// 计算水印字体大小
		addTextWatermark(watermarkText, image, graphics, watermarkedImage);

		// 输出带有水印的图片
		File outputFile = new File(output);
		ImageIO.write(watermarkedImage, "webp", outputFile);

		// 释放资源
		graphics.dispose();
	}

	/**
	 * 给原图添加文字水印
	 *
	 * @param watermarkText    水印文字
	 * @param image            图片
	 * @param graphics         图形
	 * @param watermarkedImage 水印图
	 */
	private static void addTextWatermark(String watermarkText, BufferedImage image, Graphics2D graphics, BufferedImage watermarkedImage) {
		int fontSize = calculateFontSize(image);
		System.out.println("fontSize: " + fontSize);

		// 设置水印文本样式
		Font font = new Font("Arial", Font.BOLD, fontSize);
        // 设置水印文本颜色和透明度
		Color color = new Color(255, 255, 255, 128); 

		// 添加水印
		graphics.setColor(color);
		graphics.setFont(font);
		graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
		graphics.drawString(watermarkText, 10, watermarkedImage.getHeight() - 10);
	}

	/**
	 * 计算水印文字大小
	 *
	 * @param image 图片
	 * @return 文字字号
	 */
	private static int calculateFontSize(BufferedImage image) {
		// 获取图片的高度
		int imageHeight = image.getHeight();
		// 计算字体大小，可以根据需要调整比例系数，最小字体12
		return Math.max(imageHeight / 20, 12);
	}


	/**
	 * 计算图片压缩率
	 *
	 * @param originalFilePath   原图路径
	 * @param compressedFilePath 压缩后的图片路径
	 * @return 压缩率
	 */
	public static double calculateCompressionRatio(String originalFilePath, String compressedFilePath) {
		File originalFile = new File(originalFilePath);
		File compressedFile = new File(compressedFilePath);

		long originalFileSize = originalFile.length();
		long compressedFileSize = compressedFile.length();
		return ((double) originalFileSize - compressedFileSize) / originalFileSize * 100;
	}

}