根据Apache Poi写了个基于Web的Excel文件生成工具

不废话直接上代码

/**
 *
 * Excel文件生成类
 * 工具包POI
 */
public class ExcelUtils {
    /**
     * 创建workBook
     * @return
     */
    public static XSSFWorkbook createExcelWorkBook(){
        return new XSSFWorkbook();
    }

    /**
     * 从获取枚举类中获取单元格样式
     * @param workbook
     * @param cellStyleEnum  单元格样式枚举类
     * @return
     */
    public static CellStyle getCellStyle(XSSFWorkbook workbook, CellStyleEnum cellStyleEnum){
        CellStyle cellStyle = cellStyleEnum.getCellStyle(workbook);
        return cellStyle;
    }

    /**
     * 创建sheet
     * @param xssfWorkbook
     * @param sheetName sheet名
     * @return
     */
    public static XSSFSheet createAndGetExcelSheet(XSSFWorkbook xssfWorkbook,String sheetName){
        XSSFSheet sheet = xssfWorkbook.createSheet(sheetName);
        return sheet;
    }

    /**
     * 将数据生成到sheet
     * @param sheet
     * @param cellStyle 单元格样式
     * @param dataList  数据列表
     * @param <T>
     * @throws BusinessException
     */
    public static <T> void writeExcelCell(XSSFSheet sheet,CellStyle cellStyle, List<T> dataList) throws BusinessException{
        if(ObjectUtils.isEmpty(dataList)){
            return;
        }
        T t1 = dataList.get(0);
        Field[] declaredFields = t1.getClass().getDeclaredFields();
        //列名和字段的映射关系
        LinkedHashMap<String,Field> linkedHashMap = new LinkedHashMap<>(declaredFields.length);

        for(Field field:declaredFields){
            ExcelField declaredAnnotation = field.getDeclaredAnnotation(ExcelField.class);
            //包含ExcelField注解的才在Excel文件中展示
            if(declaredAnnotation!=null){
                field.setAccessible(true);
                linkedHashMap.put(declaredAnnotation.columnName(),field);
            }
        }
        String[] columnNames = linkedHashMap.keySet().toArray(new String[]{});
        if(linkedHashMap.isEmpty()){
            throw new BusinessException("Sheet无可输出的列，请检查对象是否包含@ExcelField");
        }
        //先打印列名
        for(int i=0;i<columnNames.length;i++){
            writeExcelCell(sheet,cellStyle,columnNames[i],0,i);
        }
        //余下值从第1行开始输出
        int beginRow =1;
        for(int i=0;i<dataList.size();i++){
            for(int j=0;j<columnNames.length;j++){
                try {
                    writeExcelCell(sheet,cellStyle,linkedHashMap.get(columnNames[j]).get(dataList.get(i)),i+beginRow,j);
                } catch (IllegalAccessException e) {
                    throw new BusinessException(String.format("导出Excel文件出现数据异常，原因[%s],异常值为[%s]",e.getMessage(),GsonUtil.getGson().toJson(dataList.get(i))));
                }

            }
        }
        //让sheet的列宽自适应
        for(int j=0;j<columnNames.length;j++) {
            sheet.autoSizeColumn(j);
        }
    }

        /**
         * 创建单元格和录入值
         * @param sheet
         * @param data
         * @param row
         * @param column
         */
    public static void writeExcelCell(XSSFSheet sheet,CellStyle cellStyle, Object data, int row, int column){
        XSSFRow xssfRow = executeFunctionIfNull(sheet, sheet.getRow(row), a -> a.createRow(row));
        XSSFCell cell = executeFunctionIfNull(xssfRow, xssfRow.getCell(column), a -> a.createCell(column));
        cell.setCellStyle(cellStyle);
        setCellTypeAndValue(data,cell);
    }

    /**
     * 创建单元格类型和设置值
     * @param data
     * @param cell
     */
    public static void setCellTypeAndValue(Object data,XSSFCell cell){
        if(data == null){
            return ;
        }
        if(data instanceof Number){
            cell.setCellType(CellType.NUMERIC);
            cell.setCellValue(Double.parseDouble(data.toString()));
        }else if(data instanceof Boolean){
            cell.setCellType(CellType.BOOLEAN);
            cell.setCellValue(Boolean.valueOf(data.toString()));
        }else{
            cell.setCellType(CellType.STRING);
            cell.setCellValue(data.toString());
        }
    }

    /**
     * 如果obj为空，则使用t和function构造相同类型的返回，否则返回obj
     * @param t
     * @param obj
     * @param function
     * @param <T>
     * @param <R>
     * @return
     */
    public static <T,R> R executeFunctionIfNull(T t, R obj, Function<T,R> function){
        if(obj==null){
            return function.apply(t);
        }
        return obj;
    }

    /**
     * 直接将workBook输出给用户
     * @param request
     * @param response
     * @param workbook
     * @param fileName
     * @throws BusinessException
     */
    public static void downloadExcelFile(HttpServletRequest request, HttpServletResponse response, XSSFWorkbook workbook,String fileName) throws BusinessException{
        if(workbook==null){
            throw new BusinessException("workBook为空,Excel文件生成失败");
        }
        if(fileName==null){
            fileName = "excel";
        }
        //文件名可以不指定文件格式，统一生成xlsx格式。
        fileName = fileName.replaceAll("\\..*","")+".xlsx";
        String userAgent = Optional.ofNullable(request.getHeader("user-agent")).orElse("").toLowerCase();
        OutputStream toClient = null;
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        try{
            if (userAgent.contains("msie") || userAgent.contains("like gecko")) {
                // win10 ie edge 浏览器 和其他系统的ie
                fileName = URLEncoder.encode(fileName, "UTF-8");
            }else {
                // fe
                fileName = new String(fileName.getBytes("UTF-8"), "iso-8859-1");
            }
            workbook.write(byteArrayOutputStream);
            byte[] bytes = byteArrayOutputStream.toByteArray();
            // 清空response
            response.reset();
            // 设置response的Header
            response.addHeader("Content-Disposition", "attachment;filename=" + fileName);
            response.addHeader("Content-Length",String.valueOf(bytes.length));
            //说明返回对象类型是文件
            response.setContentType("application/octet-stream");
            toClient = new BufferedOutputStream(response.getOutputStream());
            workbook.write(toClient);
            toClient.write(bytes);
            toClient.flush();
        }catch (Exception e){
            throw new BusinessException(String.format("下载文件出现异常，文件名：[%s],异常信息[%s]",fileName,e.getMessage()));
        }finally {
            if(toClient!=null){
                try {
                    toClient.close();
                } catch (IOException e) {
                    throw new BusinessException(String.format("下载文件后关闭IO输出流出现异常，原因[%s]",e.getMessage()));
                }
            }
            try {
                byteArrayOutputStream.close();
            } catch (IOException e) {
                throw new BusinessException(String.format("下载文件后关闭用于辅助展示文件大小的IO输出流出现异常，原因[%s]",e.getMessage()));
            }
        }
    }
}

上述的BusinessException是自定义的运行时异常类，如下：

public class BusinessException extends RuntimeException{

    public BusinessException(String message) {
        super(message);
    }

    public BusinessException(Throwable cause){
        super(cause);
    }
}

自定义的注解ExcelField（当时设计是这么考虑的，要打印的字段总要有列名，因此作用在字段上，因此考虑使用自定义注解，方便理解）：

import java.lang.annotation.*;

/**
 * 自定义注解，配合ExcelUtils工具类使用，无该注解的字段不输出到Excel文件中
 */
@Target(ElementType.FIELD)
@Documented
@Retention(RetentionPolicy.RUNTIME)
public @interface ExcelField {
    /**
     * 表头名
     * @return
     */
    public String columnName();

}

自定义的样式枚举类如下：

import org.apache.poi.ss.usermodel.BorderStyle;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

/**
 */

/**
 * Excel单元格的样式枚举类
 * @author dd-zhanjx
 */
public enum CellStyleEnum {
    /**
     * DEFAULT 默认样式，上下左右边框为细边，12字号的宋体
     */
    DEFAULT{
        @Override
        public CellStyle getCellStyle(XSSFWorkbook workbook) {
            CellStyle cellStyle = workbook.createCellStyle();
            //设置上下左右边框样式
            cellStyle.setBorderBottom(BorderStyle.THIN);
            cellStyle.setBorderLeft(BorderStyle.THIN);
            cellStyle.setBorderRight(BorderStyle.THIN);
            cellStyle.setBorderTop(BorderStyle.THIN);
            //设置字体大小和样式
            Font font = workbook.createFont();
            font.setFontName("宋体");
            font.setFontHeightInPoints(new Short("12"));
            cellStyle.setFont(font);
            return cellStyle;
        }
    };
    public abstract CellStyle getCellStyle(XSSFWorkbook workbook);
}

public class SubscribeUserBO {
 @ExcelField(columnName = "用户名")
 private String userName;
     public String getUserName() {
        return userName;
    }

    public void setClientName(String userName) {
        this.userName = userName;
    }
}

使用ExcelUtils的Demo

public void demo(HttpServletRequest request, HttpServletResponse response,List<XXXclass> data){
 XSSFWorkbook excelWorkBook = ExcelUtils.createExcelWorkBook();
 XSSFSheet xssfSheet = ExcelUtils.createAndGetExcelSheet(excelWorkBook, fundCode);
 //获取默认单元格样式
 CellStyle cellStyle = ExcelUtils.getCellStyle(excelWorkBook, CellStyleEnum.DEFAULT);
 ExcelUtils.writeExcelCell(xssfSheet,cellStyle,data);
 ExcelUtils.downloadExcelFile(request,response,excelWorkBook,"excel");
}

使用到的poi依赖（项目是使用gradle搭建的，需要pom格式的可以去maven仓库查询）

    compile group: 'org.apache.poi', name: 'poi', version: '4.0.1'
    compile group: 'org.apache.poi', name: 'poi-excelant', version: '4.0.1'
    compile group: 'org.apache.poi', name: 'poi-scratchpad', version: '4.0.1'