使用layui在前端接收后端的图片流来显示二维码

消息弹框的形式

因为我是在生成二维码之后，用zxing的工具类输出的流
所以这里介绍一下我用到的工具类的依赖

gradle

// https://mvnrepository.com/artifact/com.google.zxing/javase
compile group: 'com.google.zxing', name: 'javase', version: '3.2.1'

maven

<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>javase</artifactId>
    <version>3.2.1</version>
</dependency>

我这里的前端是coffee，如果是纯js的话改成js就行了

这里要注意一点，就是在请求后端的时候是以get请求方式请求的

coffee demo

html = ""
            layer.open(
                type: 1
                ,title : false
                ,closeBtn: false	//上面的demo的图片右上角有关闭X要去掉的话，加上这一行设置就行
                ,offset: 'auto'
                ,id: 'layerDemo'+ shipmentId
                ,content: html
                ,btn: '关闭'
                ,btnAlign: 'c'
                ,shade: 0
                ,yes: () ->
                    layer.closeAll();
            )

从官网捞了个js的demo

var html = ""
layer.open({
        type: 1
        ,offset: type //具体配置参考：http://www.layui.com/doc/modules/layer.html#offset
        ,id: 'layerDemo'+type //防止重复弹出
        ,content: html
        ,btn: '关闭全部'
        ,btnAlign: 'c' //按钮居中
        ,shade: 0 //不显示遮罩
        ,yes: function(){
          layer.closeAll();
        }
      });

前端大致就是上面这样，后端的话这里也给个demo,后端controller我用的springmvc
主要思路是把图片流写到response输出流中

controller

ResponseMessage generateQRCode(TtxSession sess,HttpServletResponse response,Long shipmentId){
        ServletOutputStream stream = null;
        try {
            ShipmentHeader sh = shSvc.getEntity(sess,shipmentId)
            String sql = """
                          select * 
                          from config_detail 
                          where warehouseCode = ? and recordType = 'invoiceValues' and identifier = 'qrCodePath'
                         """

            List<ConfigDetail> configDetails = template(sess).query(sql,new BeanPropertyRowMapper<ConfigDetail>(ConfigDetail.class),sh.warehouseCode)

            if(CollectionUtils.isEmpty(configDetails) || StringUtils.isEmpty(configDetails[0]?.value1)){
                return ResponseMessageFactory.error(sess,WaveMessages.MSG_WAVE_0147)
            }

            String selfDefine = configDetails[0].value2
            Map selfDefineMap = JSON.readValue(selfDefine,Map.class)
            Integer pictureSize = selfDefineMap.get("pictureSize") as Integer
            String picForm = selfDefineMap.get("pictureForm")
            String path = configDetails[0].value1

            String sepa = Matcher.quoteReplacement(File.separator)
            path = path.replaceAll("/",sepa)

            String filename = path + sh.code + "." + picForm
            BitMatrix bitMatrix = QRCodeUtil.createQRCode(sh.invoiceUrl,pictureSize,pictureSize)
            MatrixToImageWriter.writeToPath(bitMatrix,picForm,new File(filename).toPath())
			//输出到前端的图片肯定是要最新的不能有缓存,所以要设置no cache
			response.setHeader("Cache-Control","no-store");
            response.setHeader("Pragma","no-cache");
            response.setDateHeader("Expires",0);
            response.setContentType("image/jpg");	//设置格式,就是下面的picForm,我这里举了个jpg格式的例子
            stream = response.getOutputStream()
            //参数依次是：图片矩阵，图片格式picForm=jpg，ServletOutputStream stream = response.getOutputStream()
            MatrixToImageWriter.writeToStream(bitMatrix,picForm,stream)
            return ResponseMessageFactory.success(sess)
        } catch (Throwable t) {
            ExceptionManager.logException(sess,t)
            return ResponseMessageFactory.error(sess,t.getMessage())
        }finally{
            if (stream != null) {
                stream.flush();
                stream.close();
            }
        }

呃，上面的 bitMatrix 矩阵对象的来源在我生成二维码的博文那儿有

https://blog.csdn.net/weixin_43944305/article/details/106701133