回答

在 Spring Boot 应用中，可以使用 Java 的图像处理库（如 java.awt 和 javax.imageio）来实现图片水印和裁剪功能。以下是一个示例，展示如何实现这些功能。

1. 添加依赖

确保你的 pom.xml 中包含以下依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

2. 创建图片处理服务

创建一个服务类，用于处理图片的水印和裁剪功能。

import org.springframework.stereotype.Service;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

@Service
public class ImageService {

    public BufferedImage addWatermark(BufferedImage sourceImage, String watermarkText) {
        Graphics2D g2d = (Graphics2D) sourceImage.getGraphics();

        // 设置水印字体和颜色
        Font font = new Font("Arial", Font.BOLD, 30);
        g2d.setFont(font);
        g2d.setColor(new Color(255, 0, 0, 80)); // 红色，透明度80

        // 计算水印位置
        FontMetrics fontMetrics = g2d.getFontMetrics();
        int x = sourceImage.getWidth() - fontMetrics.stringWidth(watermarkText) - 10;
        int y = sourceImage.getHeight() - fontMetrics.getHeight() + 30;

        // 添加水印
        g2d.drawString(watermarkText, x, y);
        g2d.dispose();

        return sourceImage;
    }

    public BufferedImage cropImage(BufferedImage sourceImage, int x, int y, int width, int height) {
        return sourceImage.getSubimage(x, y, width, height);
    }

    public void saveImage(BufferedImage image, String formatName, File output) throws IOException {
        ImageIO.write(image, formatName, output);
    }
}

3. 创建控制器

创建一个控制器，提供 API 接口来处理图片的水印和裁剪请求。

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

@RestController
@RequestMapping("/api/images")
public class ImageController {

    @Autowired
    private ImageService imageService;

    @PostMapping("/watermark")
    public ResponseEntity<String> addWatermark(@RequestParam("file") MultipartFile file,
                                               @RequestParam("text") String text) {
        try {
            BufferedImage sourceImage = ImageIO.read(file.getInputStream());
            BufferedImage watermarkedImage = imageService.addWatermark(sourceImage, text);

            // 保存处理后的图片
            File output = new File("watermarked_image.png");
            imageService.saveImage(watermarkedImage, "png", output);

            return ResponseEntity.ok("Watermark added successfully. Saved as watermarked_image.png");
        } catch (IOException e) {
            e.printStackTrace();
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("Failed to add watermark");
        }
    }

    @PostMapping("/crop")
    public ResponseEntity<String> cropImage(@RequestParam("file") MultipartFile file,
                                            @RequestParam("x") int x,
                                            @RequestParam("y") int y,
                                            @RequestParam("width") int width,
                                            @RequestParam("height") int height) {
        try {
            BufferedImage sourceImage = ImageIO.read(file.getInputStream());
            BufferedImage croppedImage = imageService.cropImage(sourceImage, x, y, width, height);

            // 保存处理后的图片
            File output = new File("cropped_image.png");
            imageService.saveImage(croppedImage, "png", output);

            return ResponseEntity.ok("Image cropped successfully. Saved as cropped_image.png");
        } catch (IOException e) {
            e.printStackTrace();
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("Failed to crop image");
        }
    }
}

4. 测试 API

你可以使用工具（如 Postman）来测试这些 API。

添加水印URL: POST http://localhost:8080/api/images/watermark参数:file: 上传的图片文件text: 水印文字裁剪图片URL: POST http://localhost:8080/api/images/crop参数:file: 上传的图片文件x: 裁剪区域的起始 x 坐标y: 裁剪区域的起始 y 坐标width: 裁剪区域的宽度height: 裁剪区域的高度总结

通过上述步骤，你可以在 Spring Boot 应用中实现图片的水印和裁剪功能。这些功能可以根据具体需求进行扩展和优化。