轉自：https://www.cnblogs.com/kyliechen/p/10732760.html

1.匯入poi相關jar包

對於只操作2003及以前版本的excel，只需要匯入poi-XXX.jar ，如果還需要對2007及以後版本進行操作，則需要匯入

poi-ooxml-XXX.jar

poi-ooxml-schemas-XXX.jar

2.讀取excel檔案

ImportExcel工具類

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

 
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ImportExcel {
    // abc.xls
    public static boolean isXls(String fileName){
        // (?i)忽略大小寫
        if(fileName.matches("^.+\\.(?i)(xls)$")){
            return
 
 true;
        }else if(fileName.matches("^.+\\.(?i)(xlsx)$")){
            return false;
        }else{
            throw new RuntimeException("格式不對");
        }
    }

    public static List<Map<String, Object>> readExcel(String fileName, InputStream inputStream) throws Exception{

        
 
boolean ret = isXls(fileName);
        Workbook workbook = null;
        // 根據字尾建立不同的物件
        if(ret){
            workbook = new HSSFWorkbook(inputStream);
        }else{
            workbook = new XSSFWorkbook(inputStream);
        }
        Sheet sheet = workbook.getSheetAt(0);
        // 得到標題行
        Row titleRow = sheet.getRow(0);

        int lastRowNum = sheet.getLastRowNum();
        int lastCellNum = titleRow.getLastCellNum();

        List<Map<String, Object>> list = new ArrayList<>();

        for(int i = 1; i <= lastRowNum; i++ ){
            Map<String, Object> map = new HashMap<>();
            Row row = sheet.getRow(i);
            for(int j = 0; j < lastCellNum; j++){
                // 得到列名
                String key = titleRow.getCell(j).getStringCellValue();
                Cell cell = row.getCell(j);
                cell.setCellType(CellType.STRING);

                map.put(key, cell.getStringCellValue());
            }
            list.add(map);
        }
        workbook.close();
        return list;

    }
}

前端：給出上傳連結

<div class="layui-form-item">
            <label class="layui-form-label">選擇檔案</label>
            <div class="layui-input-block">
                <input type="file" name="mFile" id="no1" class="layui-input">
            </div>
        </div>
        <div class="layui-form-item">
            <input class="layui-btn" style="margin-left: 10%"  id="btn1" type="submit" value="確認匯入">
        </div>

後臺controller層處理接收的excel檔案

@RequestMapping("/staff/import.do")
    @ResponseBody
    public JsonBean importExcel(@RequestParam MultipartFile mFile){
        try {
            String fileName = mFile.getOriginalFilename();
            // 獲取上傳檔案的輸入流
            InputStream inputStream = mFile.getInputStream();
            // 呼叫工具類中方法，讀取excel檔案中資料
            List<Map<String, Object>> sourceList = ImportExcel.readExcel(fileName, inputStream);

            // 將物件先轉為json格式字串，然後再轉為List<SysUser> 物件
            ObjectMapper objMapper = new ObjectMapper();
            String infos = objMapper.writeValueAsString(sourceList);

            // json字串轉物件
            List<Staff> list = objMapper.readValue(infos, new TypeReference<List<Staff>>() {});

            // 批量新增
            staffService.addStaffBatch(list);

            return JsonUtils.createJsonBean(1, null);

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();

            return JsonUtils.createJsonBean(0, e.getMessage());
        }

    }

【注意】excel每個列名要和資料庫欄位名一致！！

對於有date型別的資料，excel輸入2019-12-12會變為日期格式資料，日期型別傳到後臺時會轉成字串，其格式會出錯，就無法轉換Date型別，

所以Excel表格一定要將時間相關資料用文字格式儲存！！！

資料庫對應實體類與時間相關屬性要新增@DateTimeFormat(pattern="yyyy-MM-dd")註解