SpringBoot Controller返回图片的三种方式

import org.springframework.util.Base64Utils;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;

@RestController
public class ImageController {

    @GetMapping("/image")
    public String getImageAsBase64() throws IOException {
        // 读取图片文件
        File file = new File("path/to/your/image.jpg");
        byte[] imageBytes = Files.readAllBytes(file.toPath());
        
        // 将图片字节数组进行 Base64 编码
        String base64EncodedImage = Base64Utils.encodeToString(imageBytes);
        
        // 返回 Base64 编码后的图片字符串
        return base64EncodedImage;
    }
}

import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
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 org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

@RestController
public class ImageController {

    @GetMapping("/image")
    public ResponseEntity<byte[]> getImageAsByteArray() throws IOException {
        // 读取图片文件
        File file = new File("path/to/your/image.jpg");
        byte[] imageBytes = Files.readAllBytes(file.toPath());

        // 构建 HTTP 响应头
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.IMAGE_JPEG);
        headers.setContentLength(imageBytes.length);

        // 返回包含图片字节数组的 ResponseEntity
        return new ResponseEntity<>(imageBytes, headers, HttpStatus.OK);
    }
}

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 org.springframework.web.servlet.support.ServletUriComponentsBuilder;

import java.io.IOException;

@RestController
public class ImageController {

    @GetMapping("/image")
    public ResponseEntity<Resource> getImage() throws IOException {
        // 加载图片资源
        Resource resource = loadResource("path/to/your/image.jpg");

        // 构建响应
        return ResponseEntity.ok()
                .contentType(MediaType.IMAGE_JPEG)
                .body(resource);
    }

    private Resource loadResource(String imagePath) {
        // 实现加载图片资源的逻辑，这里可以是文件系统、类路径、网络等不同位置
        // 这里的示例是加载文件系统中的图片
        return new FileSystemResource(imagePath);
    }
}