SpringMVC、mybatis查询数据库中的二进制文件，在前端页面显示图片

浅浅的花香味﹌ 2022-05-20 08:06 176阅读 0赞

> 在做项目的时候，图片一般是存在单独的服务器中，数据库中只存url地址，这样做事比较好的，减轻了数据库的压力，存取图片的时候也简单。然而，也不排除直接将二进制文件存到数据库中的情况，这种做法，无论是存还是取都不方便，也增加了数据库的压力，所以尽量避免这种做法。

*  JavaBean

public class CustomerPMProduct {
        private String name;//产品名称
        private Float weightAu;//含金量
        private String standard;//规格
        private Float remainAmount;//剩余量
        private byte[] thumbnail;//缩略图，这个就是二进制字段
        public String getStandard() {
            return standard;
        }
        public void setStandard(String standard) {
            this.standard = standard;
        }
    
        public byte[] getThumbnail() {
            return thumbnail;
        }
    
        public void setThumbnail(byte[] thumbnail) {
            this.thumbnail = thumbnail;
        }
    
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Float getWeightAu() {
            return weightAu;
        }
    
        public void setWeightAu(Float weightAu) {
            this.weightAu = weightAu;
        }
    
        public Float getRemainAmount() {
            return remainAmount;
        }
    
        public void setRemainAmount(Float remainAmount) {
            this.remainAmount = remainAmount;
        }
    
    }

*  mapper.java接口

@Component
    public interface CustomerPMProductMapper {
        CustomerPMProduct selectPMProduct();
    }

*  mapper.xml文件

<select id="selectPMProduct" resultType="com.yihuisoft.testprojectbiz.entity.CustomerPMProduct">
            SELECT name,
              weight_au weightAu,
              standard,
              REMAIN_AMOUNT remainAmount,
              THUMBNAIL01 thumbnail
            FROM
              (SELECT name,
                weight_au,
                standard,
                REMAIN_AMOUNT ,
                THUMBNAIL01
              FROM PM_PRODUCT
              WHERE exp_yield IS NOT NULL
              ORDER BY exp_yield DESC
              )
            WHERE rownum=1
        </select>

*  service

public OutDTO selectPMProduct(InDTO inDTO){
            OutDTO outDTO = new OutDTO();
            CustomerPMProduct pmProduct = wealthSuccessionMapper.selectPMProduct();
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("data",pmProduct);
            outDTO.setData(jsonObject);
            return outDTO;
        }

*  前端显示
 *  image标签

*  js

document.getElementById("img1").src = "data:image/png;base64,"+this.pmProduct.thumbnail;