Excel导入导出工具类（完整版）

一.ExcelUtil工具类

package com.gdz.excel.util;


import java.io.*;
import java.lang.reflect.Field;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.*;

import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.xssf.streaming.SXSSFSheet;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import javax.servlet.http.HttpServletResponse;

/**
 * Excel导入导出
 * @Author: guandezhi
 * @Date: 2019/3/9 9:47
 */
public class ExcelUtil {

    /**
     * 导出多个sheet的excel
     * @param name
     * @param mapList
     * @param response
     * @param <T>
     */
    public static <T> void exportMultisheetExcel(String name, List<Map> mapList, HttpServletResponse response) {
        BufferedOutputStream bos = null;
        try {
            String fileName = name + ".xlsx";
            bos = getBufferedOutputStream(fileName, response);
            doExport(mapList, bos);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (bos != null) {
                    bos.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 从excel中读内容
     * @param filePath
     * @param sheetIndex
     * @return
     */
    public static List<Map<String, String>> readExcel(String filePath, Integer sheetIndex) {
        List<Map<String, String>> dataList = new ArrayList<>();
        Workbook wb = ExcelUtil.createWorkBook(filePath);
        if (wb != null) {
            Sheet sheet = wb.getSheetAt(sheetIndex);
            int maxRownum = sheet.getPhysicalNumberOfRows();
            Row firstRow = sheet.getRow(0);
            int maxColnum = firstRow.getPhysicalNumberOfCells();
            String columns[] = new String[maxColnum];
            for (int i = 0; i < maxRownum; i++) {
                Map<String, String> map = null;
                if (i > 0) {
                    map = new LinkedHashMap<>();
                    firstRow = sheet.getRow(i);
                }
                if (firstRow != null) {
                    String cellData = null;
                    for (int j = 0; j < maxColnum; j++) {
                        cellData = (String) ExcelUtil.getCellFormatValue(firstRow.getCell(j));
                        if (i == 0) {
                            columns[j] = cellData;
                        } else {
                            map.put(columns[j], cellData);
                        }
                    }
                } else {
                    break;
                }
                if (i > 0) {
                    dataList.add(map);
                }
            }
        }
        return dataList;
    }

    private static BufferedOutputStream getBufferedOutputStream(String fileName, HttpServletResponse response) throws Exception {
        response.setContentType("application/x-msdownload");
        response.setHeader("Content-Disposition", "attachment;filename="
                + new String(fileName.getBytes("gb2312"), "ISO8859-1"));
        return new BufferedOutputStream(response.getOutputStream());
    }

    private static <T> void doExport(List<Map> mapList, OutputStream outputStream) {
        int maxBuff = 100;
        // 创建excel工作文本，100表示默认允许保存在内存中的行数
        SXSSFWorkbook wb = new SXSSFWorkbook(maxBuff);
        try {
            for (int i = 0; i < mapList.size(); i++) {
                Map map = mapList.get(i);
                String[] headers = (String[]) map.get("headers");
                Collection<T> dataList = (Collection<T>) map.get("dataList");
                String fileName = (String) map.get("fileName");
                createSheet(wb, null, headers, dataList, fileName, maxBuff);
            }

            if (outputStream != null) {
                wb.write(outputStream);
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }

    }

    private static <T> void createSheet(SXSSFWorkbook wb, String[] exportFields, String[] headers, Collection<T> dataList, String fileName, int maxBuff) throws NoSuchFieldException, IllegalAccessException, IOException {

        Sheet sh = wb.createSheet(fileName);

        CellStyle style = wb.createCellStyle();
        CellStyle style2 = wb.createCellStyle();
        //创建表头
        Font font = wb.createFont();
        font.setFontName("微软雅黑");
        font.setFontHeightInPoints((short) 11);//设置字体大小
        style.setFont(font);//选择需要用到的字体格式

        style.setFillForegroundColor(HSSFColor.YELLOW.index);// 设置背景色
        style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        style.setAlignment(HSSFCellStyle.ALIGN_CENTER); // 居中
        style.setBorderBottom(HSSFCellStyle.BORDER_THIN); //下边框
        style.setBorderRight(HSSFCellStyle.BORDER_THIN);//右边框

        style2.setFont(font);//选择需要用到的字体格式

        style2.setFillForegroundColor(HSSFColor.WHITE.index);// 设置背景色
        style2.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        style2.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER); //垂直居中
        style2.setAlignment(HSSFCellStyle.ALIGN_CENTER); // 水平向下居中
        style2.setBorderBottom(HSSFCellStyle.BORDER_THIN); //下边框
        style2.setBorderRight(HSSFCellStyle.BORDER_THIN);//右边框
        style2.setBorderLeft(HSSFCellStyle.BORDER_THIN);//左边框
        style2.setBorderTop(HSSFCellStyle.BORDER_THIN);//上边框

        Row headerRow = sh.createRow(0); //表头

        int headerSize = headers.length;
        for (int cellnum = 0; cellnum < headerSize; cellnum++) {
            Cell cell = headerRow.createCell(cellnum);
            cell.setCellStyle(style);
            sh.setColumnWidth(cellnum, 4000);
            cell.setCellValue(headers[cellnum]);
        }

        int rownum = 0;
        Iterator<T> iterator = dataList.iterator();
        while (iterator.hasNext()) {
            T data = iterator.next();
            Row row = sh.createRow(rownum + 1);

            Field[] fields = getExportFields(data.getClass(), exportFields);
            for (int cellnum = 0; cellnum < headerSize; cellnum++) {
                Cell cell = row.createCell(cellnum);
                cell.setCellStyle(style2);
                Field field = fields[cellnum];

                setData(field, data, field.getName(), cell);
            }
            rownum = sh.getLastRowNum();
            // 大数据量时将之前的数据保存到硬盘
            if (rownum % maxBuff == 0) {
                ((SXSSFSheet) sh).flushRows(maxBuff); // 超过100行后将之前的数据刷新到硬盘

            }
        }
    }


    private static <T> void doExport(String[] headers, String[] exportFields, Collection<T> dataList,
                                     String fileName, OutputStream outputStream) {

        int maxBuff = 100;
        // 创建excel工作文本，100表示默认允许保存在内存中的行数
        SXSSFWorkbook wb = new SXSSFWorkbook(maxBuff);
        try {
            createSheet(wb, exportFields, headers, dataList, fileName, maxBuff);
            if (outputStream != null) {
                wb.write(outputStream);
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    /**
     * 获取单条数据的属性
     *
     * @param object
     * @param property
     * @param <T>
     * @return
     * @throws NoSuchFieldException
     * @throws IllegalAccessException
     */
    private static <T> Field getDataField(T object, String property) throws NoSuchFieldException, IllegalAccessException {
        Field dataField;
        if (property.contains(".")) {
            String p = property.substring(0, property.indexOf("."));
            dataField = object.getClass().getDeclaredField(p);
            return dataField;
        } else {
            dataField = object.getClass().getDeclaredField(property);
        }
        return dataField;
    }

    private static Field[] getExportFields(Class<?> targetClass, String[] exportFieldNames) {
        Field[] fields = null;
        if (exportFieldNames == null || exportFieldNames.length < 1) {
            fields = targetClass.getDeclaredFields();
        } else {
            fields = new Field[exportFieldNames.length];
            for (int i = 0; i < exportFieldNames.length; i++) {
                try {
                    fields[i] = targetClass.getDeclaredField(exportFieldNames[i]);
                } catch (Exception e) {
                    try {
                        fields[i] = targetClass.getSuperclass().getDeclaredField(exportFieldNames[i]);
                    } catch (Exception e1) {
                        throw new IllegalArgumentException("无法获取导出字段", e);
                    }

                }
            }
        }
        return fields;
    }

    /**
     * 根据属性设置对应的属性值
     *
     * @param dataField 属性
     * @param object    数据对象
     * @param property  表头的属性映射
     * @param cell      单元格
     * @param <T>
     * @return
     * @throws IllegalAccessException
     * @throws NoSuchFieldException
     */
    private static <T> void setData(Field dataField, T object, String property, Cell cell)
            throws IllegalAccessException, NoSuchFieldException {
        dataField.setAccessible(true); //允许访问private属性
        Object val = dataField.get(object); //获取属性值
        Sheet sh = cell.getSheet(); //获取excel工作区
        CellStyle style = cell.getCellStyle(); //获取单元格样式
        int cellnum = cell.getColumnIndex();
        if (val != null) {
            if (dataField.getType().toString().endsWith("String")) {
                cell.setCellValue((String) val);
            } else if (dataField.getType().toString().endsWith("Integer") || dataField.getType().toString().endsWith("int")) {
                cell.setCellValue((Integer) val);
            } else if (dataField.getType().toString().endsWith("Long") || dataField.getType().toString().endsWith("long")) {
                cell.setCellValue(val.toString());
            } else if (dataField.getType().toString().endsWith("Double") || dataField.getType().toString().endsWith("double")) {
                cell.setCellValue((Double) val);
            } else if (dataField.getType().toString().endsWith("Date")) {
                DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                cell.setCellValue(format.format((Date) val));
            } else if (dataField.getType().toString().endsWith("List")) {
                List list1 = (List) val;
                int size = list1.size();
                for (int i = 0; i < size; i++) {
                    //加1是因为要去掉点号
                    int start = property.indexOf(dataField.getName()) + dataField.getName().length() + 1;
                    String tempProperty = property.substring(start, property.length());
                    Field field = getDataField(list1.get(i), tempProperty);
                    Cell tempCell = cell;
                    if (i > 0) {
                        int rowNum = cell.getRowIndex() + i;
                        Row row = sh.getRow(rowNum);
                        if (row == null) {//另起一行
                            row = sh.createRow(rowNum);
                            //合并之前的空白单元格（在这里需要在header中按照顺序把list类型的字段放到最后，方便显示和合并单元格）
                            for (int j = 0; j < cell.getColumnIndex(); j++) {
                                sh.addMergedRegion(new CellRangeAddress(cell.getRowIndex(), cell.getRowIndex() + size - 1, j, j));
                                Cell c = row.createCell(j);
                                c.setCellStyle(style);
                            }
                        }
                        tempCell = row.createCell(cellnum);
                        tempCell.setCellStyle(style);
                    }
                    //递归传参到单元格并获取偏移量（这里获取到的偏移量都是第二层后list的偏移量）
                    setData(field, list1.get(i), tempProperty, tempCell);
                }
            } else {
                if (property.contains(".")) {
                    String p = property.substring(property.indexOf(".") + 1, property.length());
                    Field field = getDataField(val, p);
                    setData(field, val, p, cell);
                } else {
                    cell.setCellValue(val.toString());
                }
            }
        }
    }


    private static Workbook createWorkBook(String filePath) {
        Workbook wb = null;
        if (filePath == null) {
            return null;
        }
        String extString = filePath.substring(filePath.lastIndexOf("."));
        InputStream is = null;
        try {
            is = new FileInputStream(filePath);
            if (".xls".equals(extString)) {
                return wb = new HSSFWorkbook(is);
            } else if (".xlsx".equals(extString)) {
                return wb = new XSSFWorkbook(is);
            } else {
                return wb;
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return wb;
    }

    /**
     * 将字段转为相应的格式
     * @param cell
     * @return
     */
    private static Object getCellFormatValue(Cell cell) {
        Object cellValue = null;
        if (cell != null) {
            //判断cell类型
            switch (cell.getCellType()) {
                case Cell.CELL_TYPE_NUMERIC: {
                    cellValue = String.valueOf(cell.getNumericCellValue());
                    break;
                }
                case Cell.CELL_TYPE_FORMULA: {
                    if (DateUtil.isCellDateFormatted(cell)) {
                        cellValue = cell.getDateCellValue();////转换为日期格式YYYY-mm-dd
                    } else {
                        cellValue = String.valueOf(cell.getNumericCellValue()); //数字
                    }
                    break;
                }
                case Cell.CELL_TYPE_STRING: {
                    cellValue = cell.getRichStringCellValue().getString();
                    break;
                }
                default:
                    cellValue = "";
            }
        } else {
            cellValue = "";
        }
        return cellValue;
    }

}

二.测试一下

/**
 * @Author: guandezhi
 * @Date: 2019/3/9 11:18
 */
@Slf4j
@RestController
@RequestMapping("/excel")
public class ExcelController {

    @RequestMapping(value = "/exportExcel")
    public String exportExcel(HttpServletResponse response) throws Exception {
        String[] headers = {"姓名", "性别", "年龄", "学校", "班级"};
        String fileName = "学生表";
        List<Student> studentList = new ArrayList<>();
        Student student = new Student();
        student.setStudentName("guandezhi");
        student.setGrade("三年二班");
        student.setAge(20);
        student.setSchool("XX大学");
        student.setSex("男");
        studentList.add(student);

        Map<String, Object> studentMap = new HashMap();
        studentMap.put("headers", headers);
        studentMap.put("dataList", studentList);
        studentMap.put("fileName", fileName);

        List<Map> mapList = new ArrayList();
        mapList.add(studentMap);
        ExcelUtil.exportMultisheetExcel(fileName, mapList, response);
        return "success";
    }

    @RequestMapping(value = "/readExcel")
    public String readExcel() throws Exception {
        String filePath = "F:\\student.xls";
        List<Map<String, String>> mapList = ExcelUtil.readExcel(filePath, 0);
        log.info("mapList:" + mapList);
        return "success";
    }

}

其中的student类

/**
 * @Author: guandezhi
 * @Date: 2019/3/7 9:53
 */
@Data
public class Student {

    private String studentName;

    private String sex;

    private Integer age;

    private String school;

    private String grade;
}

导出的excel数据

读取到的excel数据