实体类：

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

import javax.persistence.Lob;
import java.sql.Blob;

@TableName("PBMS_CQRJL")
@Data
public class PbmsCqrjlBean {



    /**
     * id
     */
    private String id;


    /**
     * 虫情图片
     */
    @Lob    //此注解会将blob类型数据映射为byte[]类型
    private byte[] image;
}

controller层：

    @GetMapping("/keepView")
    public ResponseEntity<String> keepView(@RequestParam("id") String id) throws IOException, SQLException {
        //假设这是你从服务层获得到的图片byte[]
        byte[] imageData = cqInfoService.keepView(id);

        if (imageData == null) {
            return ResponseEntity.notFound().build();
        }
        String base64String = Base64.getEncoder().encodeToString(imageData);
        return ResponseEntity.ok()
                .contentType(MediaType.TEXT_PLAIN) // 根据BLOB数据的实际类型选择合适的MIME类型
                .body(base64String);
    }

html:

<img id="img-url" src="" style="width: 100%;"/>

js文件：

//数据交互可自行选择，例如axios
$.ajax({
        url: "/web_cq/keepView",
        type: "GET",
        data: {id:element.dataset.image},
        success: function (response) {
            console.log("回调结果",response);
            // 将Base64字符串解码为二进制数据
            const binaryString = atob(response);
            const len = binaryString.length;
            const bytes = new Uint8Array(len);

            for (let i = 0; i < len; i++) {
                bytes[i] = binaryString.charCodeAt(i);
            }
            const blob = URL.createObjectURL(
                new Blob([bytes], {type: 'image/png'})
            );
            const imagePreview = document.getElementById('img-url');
            imagePreview.src = blob;
        },
        error: function () {
            openErrorView("操作失败，请重试！");
        }
    });