java实现把对象数组通过excel方式导出的功能

一、导入相关jar包，pom依赖如下：

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>RELEASE</version>
        </dependency>   

二、开始撸代码

　　1.如果导出功能使用的比较多，可以将其做成一个工具类，对我下面贴出的代码进行改造

   //结果返回的是写入的记录数（以下用的是自己业务场景数据）
　　public int downLoadToExcel(OutputStream outputStream,List<PaimaiMoneyVO> paimaiMoneyVOList) {
　　　　　//文档对象
        HSSFWorkbook wb = new HSSFWorkbook();
        int rowNum = 0;
        Sheet sheet = wb.createSheet("excel的标题");
        Row row0 = sheet.createRow(rowNum++);
　　　　//因为场景不同，titil不同，可以在外面写成数组当参数传进来
        row0.createCell(0).setCellValue("第一列属性名");
        row0.createCell(1).setCellValue("第二列属性名");
        row0.createCell(2).setCellValue("第三列属性名");
        row0.createCell(3).setCellValue("第四列属性名");
        row0.createCell(4).setCellValue("第五列属性名");
        row0.createCell(5).setCellValue("第六列属性名");
　　　　 if (paimaiMoneyVOList != null && paimaiMoneyVOList.size() > 0) {
            for (PaimaiMoneyVO paimaiMoneyVO : paimaiMoneyVOList) {
                Row row = sheet.createRow(rowNum++);
                row.createCell(0).setCellValue(paimaiMoneyVO.getPaimaiId());
                row.createCell(1).setCellValue(paimaiMoneyVO.getTitle());
                row.createCell(2).setCellValue(paimaiMoneyVO.getUsername());
                row.createCell(3).setCellValue(paimaiMoneyVO.getMoney()+"元");
                row.createCell(4).setCellValue("升价拍");
                row.createCell(5).setCellValue(bidder);
            }
        }
        try {
            wb.write(outputStream);
            LogEnum.LAW_WARE.info("表数据写入到excel表成功,一共写入了"+(rowNum - 1)+"条数据");
            outputStream.close();
        } catch (IOException e) {
            LogEnum.LAW_WARE.error("流关闭异常！", e);
        } finally {
            if (outputStream != null) {
                try {
                    outputStream.close();
                } catch (IOException e) {
                    LogEnum.LAW_WARE.error("流关闭异常！", e);
                }
            }
        }
        return rowNum - 1;
    }

　　2.“工具类”写好后，下面就开始使用它了，从上面的函数参数可以看到，我们需要传过去两个对象，一个是输出流OutPutStream，通过流的方式把excel想要到浏览器，

另外一个就是我们需要导出的对象数组，好了，不解释太多，看代码。（下面的方法写在action层，通过struts.xml配置访问即可实现下载）

    public void exportBail(){
        this.fileName = "excel文件名";
        try {
            List<PaimaiMoneyVO> paimaiMoneyVOList = new ArrayList<>();
　　　　　　//下面是我的业务场景获取对象数组
            if(paimaiMoneySearchParam!=null){
                paimaiMoneySearchParam.setVendorId(WebHelper.getVenderId());
                paimaiMoneySearchParam.setPageSize(Constants.AUCTION_WARE_PAGE_SIZE);
                paimaiMoneySearchParam.setPage(page);
                PaimaiMoneyDto paimaiMoneyDto = auctionWareService1.searchPopPaimaiMoneyList(paimaiMoneySearchParam);
                if(paimaiMoneyDto!=null){
                    int count = paimaiMoneyDto.getCount();
                    int totalPage = count/ Constants.AUCTION_WARE_PAGE_SIZE + (count% Constants.AUCTION_WARE_PAGE_SIZE > 0?1:0);
                    for(int i=1;i<=totalPage;i++){
                        paimaiMoneySearchParam.setPage(i);
                        PaimaiMoneyDto paimaiMoneyResultResult = auctionWareService1.searchPopPaimaiMoneyList(paimaiMoneySearchParam);
                        if(paimaiMoneyResultResult!=null){
                            paimaiMoneyVOList.addAll(paimaiMoneyResultResult.getList());
                        }
                    }
                }
            }
            OutputStream outputStream = response.getOutputStream();
            response.reset();//清空输出流
            //下面是对中文文件名的处理
            response.setCharacterEncoding("UTF-8");//设置相应内容的编码格式
　　　　　　　//解析浏览器
            final String userAgent = request.getHeader("USER-AGENT").toLowerCase();
            if(userAgent.contains("firefox")){ //火狐浏览器
                fileName = new String(fileName.getBytes(), "ISO8859-1");
            }else{
                fileName = URLEncoder.encode(fileName, "UTF-8"); //其他浏览器
　　　　　　　　　 fileName = fileName.Replace("+", "%20");  //encode后替换，解决空格问题（其中%20是空格在UTF-8下的编码 ，如果不这么写，浏览器会用+代替空格）
            }
            response.setHeader("Content-Disposition", "attachment;filename=" +fileName + ".xls");//指定输出文件名
            response.setContentType("application/msexcel");//定义输出类型
            int rouNum = ensurePriceListToExcel(outputStream,paimaiMoneyVOList);
            LogEnum.LAW_WARE.info("【RiseAuctionAction.downLoadEnsurePriceExcel】导出成功,一共更新了{"+rouNum+"}条记录");
        } catch (Exception e) {
            LogEnum.LAW_WARE.error("【RiseAuctionAction.downLoadEnsurePriceExcel】导出失败,error is {}", e);
        }
    }

三、拓展（详细的工具类开发）

　　如果你觉得上面写的太简单了，可以继续往下看，我把它整理出了“万能”的工具类，供大家参考。

package com.jd.pop.auction.util.excel;

import com.jd.common.web.result.Result;
import com.jd.pop.auction.util.excel.annotations.ExcelColumn;
import com.jd.pop.auction.util.excel.annotations.ExcelMapping;
import com.jd.pop.auction.util.excel.annotations.apt.ExcelColumnAPT;
import com.jd.pop.auction.util.excel.annotations.apt.ExcelMappingAPT;
import org.apache.log4j.Logger;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.util.CellRangeAddress;

import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

public class GenerateExcel {
    private final static Logger LOG = Logger.getLogger(GenerateExcel.class);
    private HSSFWorkbook workbook;

    private HSSFCellStyle headStyle;
    private HSSFFont headCellFont;

    private HSSFCellStyle theadStyle;
    private HSSFFont theadCellFont;

    private HSSFCellStyle tbodyStyle;
    private HSSFFont tbodyCellFont;

    private HSSFFont stringFont;

    private static final short COLUMN_WIDTH = 15;
    private static final short ROW_HEIGHT = 400;

    public GenerateExcel() {
        this.workbook = new HSSFWorkbook();
        //标题
        this.headStyle = workbook.createCellStyle();
        headStyle.setFillForegroundColor(HSSFColor.GREY_50_PERCENT.index);
        headStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
//        headStyle.setBorderBottom(HSSFCellStyle.BORDER_THIN);
//        headStyle.setBorderLeft(HSSFCellStyle.BORDER_THIN);
//        headStyle.setBorderRight(HSSFCellStyle.BORDER_THIN);
//        headStyle.setBorderTop(HSSFCellStyle.BORDER_THIN);
        headStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);

//        headStyle.setWrapText(true);
        this.headCellFont = workbook.createFont();
        headCellFont.setFontHeightInPoints((short)13);
        headCellFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
        headStyle.setFont(headCellFont);

        this.theadStyle = workbook.createCellStyle();
        theadStyle.setFillForegroundColor(HSSFColor.WHITE.index);
        theadStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        theadStyle.setBorderBottom(HSSFCellStyle.BORDER_THIN);
        theadStyle.setBorderLeft(HSSFCellStyle.BORDER_THIN);
        theadStyle.setBorderRight(HSSFCellStyle.BORDER_THIN);
        theadStyle.setBorderTop(HSSFCellStyle.BORDER_THIN);
        theadStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);

        theadCellFont = workbook.createFont();
        theadCellFont.setColor(HSSFColor.BLACK.index);
        theadCellFont.setFontHeightInPoints((short) 12);
        theadCellFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);

        theadStyle.setFont(theadCellFont);

        tbodyStyle = workbook.createCellStyle();
        tbodyStyle.setFillForegroundColor(HSSFColor.WHITE.index);
        tbodyStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        tbodyStyle.setBorderBottom(HSSFCellStyle.BORDER_THIN);
        tbodyStyle.setBorderLeft(HSSFCellStyle.BORDER_THIN);
        tbodyStyle.setBorderRight(HSSFCellStyle.BORDER_THIN);
        tbodyStyle.setBorderTop(HSSFCellStyle.BORDER_THIN);
        tbodyStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
        tbodyStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);

        tbodyCellFont = workbook.createFont();
        tbodyCellFont.setBoldweight(HSSFFont.BOLDWEIGHT_NORMAL);
        tbodyStyle.setFont(tbodyCellFont);

        stringFont = workbook.createFont();
        stringFont.setColor(HSSFColor.BLACK.index);
    }

    public <T> Result export(List<String> titles, Field[] fields, Class clazz, Collection<T> dataset, OutputStream out, boolean pager)  {
        Result  result = new Result(false);
        if(pager){

        }else{
            HSSFSheet sheet = workbook.createSheet( "第一页");

            sheet.setDefaultColumnWidth(COLUMN_WIDTH);
            sheet.setDefaultRowHeight(ROW_HEIGHT);
            //标题
            for (int i = 0; i <titles.size(); i++) {
                HSSFRow titleRow = sheet.createRow(i);
                titleRow.setHeightInPoints(20f);
                sheet.addMergedRegion(new CellRangeAddress(i,i,0,fields.length-1));
                HSSFCell titleCell =titleRow.createCell(0);
                titleCell.setCellValue(titles.get(i));
                titleCell.setCellStyle(headStyle);
            }

            //列名
            HSSFRow row = sheet.createRow(titles.size());
            for (short i = 0; i < fields.length; i++) {
                HSSFCell cell = row.createCell(i);
                cell.setCellStyle(theadStyle);
                if(fields[i].isAnnotationPresent(ExcelColumn.class)){
                    ExcelColumn an_1 = fields[i].getAnnotation(ExcelColumn.class);
                    HSSFRichTextString text = new HSSFRichTextString(an_1.name());
                    cell.setCellValue(text);
                }else if(fields[i].isAnnotationPresent(ExcelMapping.class)){
                    ExcelMapping an_1 = fields[i].getAnnotation(ExcelMapping.class);
                    HSSFRichTextString text = new HSSFRichTextString(an_1.name());
                    cell.setCellValue(text);
                }
            }

            Iterator<T> it = dataset.iterator();
            int index = titles.size();
            while (it.hasNext()) {
                index++;
                row = sheet.createRow(index);
                T t = (T) it.next();
                for (short i = 0; i < fields.length; i++) {
                    HSSFCell cell = row.createCell(i);
                    cell.setCellStyle(tbodyStyle);
                    Field field = fields[i];
                    try {
                        String textValue;
                        if(field.isAnnotationPresent(ExcelMapping.class)){
                            textValue = new ExcelMappingAPT().getColumnValue(field,t,clazz);
                        }else{
                            textValue = new ExcelColumnAPT().getColumnValue(field,t,clazz);
                        }
                        cell.setCellValue(textValue);
                    } catch (NoSuchMethodException e) {
                        String errorMsg = field.getName() +"字段，第"+ index+ "条数据， NoSuchMethodException 反射错误！";
                        LOG.error(errorMsg,e);
                        result.addDefaultModel(errorMsg);
                        return result;
                    } catch (IllegalAccessException e) {
                        String errorMsg = field.getName() +"字段，第"+ index+ "条数据， IllegalAccessException ";
                        LOG.error(errorMsg,e);
                        result.addDefaultModel(errorMsg);
                        return result;
                    } catch (InvocationTargetException e) {
                        String errorMsg = field.getName() +"字段，第"+ index+ "条数据， InvocationTargetException ";
                        LOG.error(errorMsg,e);
                        result.addDefaultModel(errorMsg);
                        return result;
                    }
                }
            }
        }

        try {
            workbook.write(out);
            result.setSuccess(true);
            return  result;
        } catch (IOException e) {
            String errorMsg = "将导出数据写入输出流失败!";
            LOG.error("将导出数据写入输出流失败！ ",e);
            result.addDefaultModel(errorMsg);
            return result;
        }finally {
            try {
                out.close();
            } catch (IOException e) {
                String errorMsg = "关闭输出流异常!";
                LOG.error("关闭输出流异常！ ",e);
                result.addDefaultModel(errorMsg);
                return result;
            }
        }
    }

}

public class ExportExcelUtils {
    private final static Logger LOG = Logger.getLogger(ExportExcelUtils.class);
    public static <T> Result export(List<String> titles,List<T> sourceList, OutputStream out, boolean pager){
        Result result  = new Result(false);
        if(CollectionUtils.isEmpty(sourceList)){
            result.addDefaultModel("ExportExcelUtils's param sourceList is empty!");
            LOG.error("ExportExcelUtils's param sourceList is empty!");
            return result;
        }
        if( out == null){
            LOG.error("ExportExcelUtils's param OutputStream is null!");
            result.addDefaultModel("ExportExcelUtils's param OutputStream is null!");
            return result;
        }
        Class clazz = null;
        Field[] fieldArr = null;
        try{
            //得到需要转换的列名
            clazz = sourceList.get(0).getClass();
            Field[] fields = clazz.getDeclaredFields();
            List<Field> fieldList = new ArrayList<Field>();
            for(Field field:Arrays.asList(fields)){
                field.setAccessible(true);
                if(field.isAnnotationPresent(ExcelColumn.class)){
                    fieldList.add(field);
                }else if(field.isAnnotationPresent(ExcelMapping.class)){
                    fieldList.add(field);
                }
            }
            if(CollectionUtils.isEmpty(fieldList)){
                LOG.error("实体类中无需要导出的字段!");
                result.addDefaultModel("实体类中无需要导出的字段！");
                return result;
            }
            fieldArr =  fieldList.toArray(new Field[fieldList.size()]);
        }catch(Exception e){
            LOG.error("数据拼装异常!");
            result.addDefaultModel("数据拼装异常!");
            return result;
        }
        //生成excel
        GenerateExcel ge = new GenerateExcel();
        return ge.export(titles,fieldArr,clazz,sourceList,out,false);
    }

}

　　这一部分写的比较粗糙，但是实现的比较详细，仅供参考，大家可以稍微改造成为自己独有的utils，上面是实战，我们可以点这里看一下POI HSSF API组件的具体使用方法。