图文并茂：解析Spring Boot Controller返回图片的三种方式

import org.springframework.core.io.InputStreamResource;
import org.springframework.core.io.Resource;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

@RestController
public class ImageController {

    // 方式一：直接返回图片资源
    @GetMapping("/image1")
    public Resource getImage1() throws IOException {
        // 假设 imagePath 是图片文件的路径
        return new InputStreamResource(new FileInputStream(imagePath));
    }

    // 方式二：返回图片的字节数组
    @GetMapping("/image2")
    public ResponseEntity<byte[]> getImage2() throws IOException {
        // 假设 imagePath 是图片文件的路径
        BufferedImage image = ImageIO.read(new File(imagePath));
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        ImageIO.write(image, "png", outputStream); // 假设是PNG格式
        return ResponseEntity.ok()
                .contentType(MediaType.IMAGE_PNG)
                .body(outputStream.toByteArray());
    }

    // 方式三：返回图片作为响应实体
    @GetMapping("/image3")
    public ResponseEntity<Resource> getImage3() throws IOException {
        // 假设 imagePath 是图片文件的路径
        Resource imageResource = new FileSystemResource(imagePath);
        return ResponseEntity.ok()
                .contentType(MediaType.IMAGE_PNG)
                .body(imageResource);
    }
}