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。