java利用反射导入导出

1.后端导入maven

 
        
            org.apache.poi
            poi
            3.15-beta2
        
        
            org.apache.poi
            poi-ooxml
            3.15-beta2
        
        
        commons-collections
        commons-collections
        3.2.2
        

2.导出表格工具类

package com.dawei.cardsolution.modules.card.utils;

import org.apache.commons.lang.time.DateFormatUtils;
import org.apache.poi.hssf.usermodel.*;
import org.apache.commons.collections.CollectionUtils;

import javax.servlet.http.HttpServletResponse;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Iterator;
import java.util.List;
import java.util.Date;


public class FilePortUtil {

    
    public static  void exportExcel(HttpServletResponse response, String title, String[] headers, List list, List containBean) throws Exception{
        HSSFWorkbook workbook = null;
        try {
            workbook = new HSSFWorkbook();
            HSSFSheet sheet = workbook.createSheet(title);
            HSSFRow row = sheet.createRow(0);
            //创建第一行表头
            for (short i = 0; i < headers.length; i++){
                HSSFCell cell = row.createCell(i);
                HSSFRichTextString textString = new HSSFRichTextString(headers[i]);
                cell.setCellValue(textString);
            }
            Iterator it = list.iterator();
            int index = 0;
            while (it.hasNext()){
                index++;
                row = sheet.createRow(index);
                T t = (T)it.next();
                //通过反射得到字段
                Field[] fields = t.getClass().getDeclaredFields();
                //如果需要匹配
                if (CollectionUtils.isEmpty(containBean)){
                    for (int j = 0; j < containBean.size(); j++){
                        for (int i = 0; i < fields.length; i++){
                            Field field  = fields[i];
                            if (!field.getName().equals(containBean.get(j)))
                                continue;
                            setCellValue(t,field,row,j);
                        }
                    }
                } else {
                    for (int i = 0; i < fields.length; i++){
                        Field field = fields[i];
                        setCellValue(t,field,row,i);
                    }
                }
            }
            response.setContentType("application/vnd.ms-excel;charset=UTF-8");
            response.addHeader("Content-Disposition", "attachment;filename=" + new String((title).getBytes(), "ISO8859-1") + ".xls");
            workbook.write(response.getOutputStream());
        }finally {
            if (workbook != null){
                workbook.close();
            }
        }
    }

    
    private static  void setCellValue(T t, Field field, HSSFRow row, int index) {
        HSSFCell cell = row.createCell(index);
        Object value = invoke(t, field);
        String textValue = null;
        if (value != null){
            if (value instanceof Date){
                Date date = (Date) value;
                textValue = DateFormatUtils.format(date,"yyyy-MM-dd HH:mm:ss");
            } else {
                textValue = value.toString();
            }
        }
        if (textValue != null){
            cell.setCellValue(textValue);
        }
    }

    
    private static  Object invoke(T t, Field field){
        try{
            String fieldName = field.getName();
            PropertyDescriptor propertyDescriptor = new PropertyDescriptor(fieldName,t.getClass());
            Method readMethod = propertyDescriptor.getReadMethod();
            return readMethod.invoke(t);
        }catch (Exception e){
            return null;
        }
    }
}

3.controller层

 
    @ResponseBody
    @GetMapping("/exportExcel")
    public void exportExcel(HttpServletResponse response){
        //导出的表格名称
        String title = "消费";

        //表中第一行表头字段
        String [] headers ={"序号","姓名","部门","卡号","消费金额","账户余额","消费类型","消费方式","是否当天第一次消费","消费时间","消费单号"};

        //从数据库查询出来的结果集
        List canteenConsumptionRecordExcels = canteenConsumptionRecordDao.selectCanteenConsumptionRecords();

        //具体需要写入excel需要的那些字段，这些字段从PprojectSalary类中拿，也就是上面的实际数据结果集的泛型
        List list = Arrays.asList("id","name","department","idCard","balance","money","consumeTypeName","typeName","isFirstName","date","cid");
        System.out.println(list);
        System.out.println(response);
        try {
            FilePortUtil.exportExcel(response,title,headers,canteenConsumptionRecordExcels,list);
        }catch (Exception e){
            e.printStackTrace();
        }
    }

4.前端接口调用 注:如果用的框架则不能使用封装的axios发请求否则会导致UTF-8失效而乱码!

 导出

     //导出 按钮
   exportOut() {
   axios({ // 用axios发送get请求
        method: 'get',
        url: window.SITE_CONFIG.baseUrl+'/card/canteenconsumptionrecord/exportExcels', //请求地址
        responseType: 'blob', // 表明返回服务器返回的数据类型
        headers: {
        token:Vue.cookie.get('token'),
      'Content-Type': 'application/json'
      }
    }).then(res => { // 处理返回的文件流
      //new Blob([res])中不加data就会返回下图中[objece objece]内容（少取一层）
      const blob = new Blob([res.data],{type: "application/vnd.ms-excel"}); 
      const fileName = '消费.xlsx';//下载文件名称
      const elink = document.createElement('a');
      elink.download = fileName;
      elink.style.display = 'none';
      elink.href = URL.createObjectURL(blob);
      document.body.appendChild(elink);
      elink.click();
      URL.revokeObjectURL(elink.href); // 释放URL 对象
      document.body.removeChild(elink);
    })
    //js方法
     
    },