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使用反射实现动态修改@Excel的注解属性

2022-07-27 05:51:00 【子非我鱼】

业务场景：我们使用poi实现数据导出时，通常是根据@Excel(name=“xxx”)来确定列名。通常情况下这个是不会发生变动的。但这里就说少数情况，在我们需要这里根据某些情况来进行改变的时候，我们就需要用到反射。

AirQualityRankingResp.java

@Data
public class AirQualityRankingResp {
    
    /** 站点名称 */
    @Excel(name = "站点名称")
    private String site;
    private String siteNumber;
    @Excel(name = "分析时间")
    private String dateTime;
    /** 污染因子 */
    private String pollutionFactor;
    @Excel(name = "AQI")
    private Double value;
    /** 排名 */
    @Excel(name = "排名")
    private Integer ranking;
}

正常使用@Excel导出数据如下

在这里插入图片描述

动态修改@Excel的属性，代码实现

  /** * 通过反射动态设置导出的Excel列名 * * @param annotatedColumnName：实体类中被@Excel注解的字段名 * @param annotationFieldName：实体类中被@Excel中注解的属性名 * @param newAnnotationFieldValue：属性的新值 */
    private void setExcelAnnotationValue(String annotatedColumnName, String annotationFieldName, String newAnnotationFieldValue){
    
        try{
    
            Class<AirQualityRankingResp> airQualityRankingRespClass = AirQualityRankingResp.class;
            Field classDeclaredField =  airQualityRankingRespClass.getDeclaredField(annotatedColumnName);
            Excel excel = classDeclaredField.getAnnotation(Excel.class);
            InvocationHandler excelInvocationHandler = Proxy.getInvocationHandler(excel);
            Field excelInvocationHandlerField = excelInvocationHandler.getClass().getDeclaredField("memberValues");
            excelInvocationHandlerField.setAccessible(true);
            Map map = (Map) excelInvocationHandlerField.get(excelInvocationHandler);
            map.put(annotationFieldName, newAnnotationFieldValue);
        } catch (Exception e) {
    
            e.printStackTrace();
        }
    }

使用示例

   @RequestMapping(value = "/rankingAnalysisExportXls")
    public ModelAndView exportXls(HttpServletRequest request, AirRankingReq airRankingReq) {
    
        switch (airRankingReq.getName()){
    
            case "2":
                setExcelAnnotationValue("value","name","SO2");
                break;
            case "3":
                setExcelAnnotationValue("value","name","NO2");
                break;
            case "4":
                setExcelAnnotationValue("value","name","PM10");
                break;
            case "5":
                setExcelAnnotationValue("value","name","CO");
                break;
            case "6":
                setExcelAnnotationValue("value","name","O3");
                break;
            case "7":
                setExcelAnnotationValue("value","name","PM2.5");
                break;
        }
        List<AirQualityRankingResp> list = lrMonitorConcentrationService.rankingAnalysis(airRankingReq);
        // Step.3 AutoPoi 导出Excel
        LoginUser sysUser = (LoginUser) SecurityUtils.getSubject().getPrincipal();
        ModelAndView mv = new ModelAndView(new JeecgEntityExcelView());
        mv.addObject(NormalExcelConstants.FILE_NAME, "lr_meteorological_data"); //此处设置的filename无效 ,前端会重更新设置一下
        mv.addObject(NormalExcelConstants.CLASS, AirQualityRankingResp.class);
        //update-begin--Author:liusq Date:20210126 for：图片导出报错，ImageBasePath未设置--------------------
        ExportParams exportParams = new ExportParams("空气质量数据排名" + "报表", "导出人:" + sysUser.getRealname(), "空气质量排名");
        exportParams.setImageBasePath(upLoadPath);
        //update-end--Author:liusq Date:20210126 for：图片导出报错，ImageBasePath未设置----------------------
        mv.addObject(NormalExcelConstants.PARAMS, exportParams);
        mv.addObject(NormalExcelConstants.DATA_LIST, list);
        return mv;
    }