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利用java如何實(shí)現(xiàn)把對(duì)象數(shù)組導(dǎo)出從Excel文件

發(fā)布時(shí)間：2020-11-12 16:12:59 來(lái)源：億速云 閱讀：259 作者：Leah 欄目：編程語(yǔ)言

利用java如何實(shí)現(xiàn)把對(duì)象數(shù)組導(dǎo)出從Excel文件？相信很多沒(méi)有經(jīng)驗(yàn)的人對(duì)此束手無(wú)策，為此本文總結(jié)了問(wèn)題出現(xiàn)的原因和解決方法，通過(guò)這篇文章希望你能解決這個(gè)問(wèn)題。

一、導(dǎo)入相關(guān)jar包，pom依賴(lài)如下：

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

二、開(kāi)始擼代碼

1.如果導(dǎo)出功能使用的比較多，可以將其做成一個(gè)工具類(lèi)，對(duì)我下面貼出的代碼進(jìn)行改造

//結(jié)果返回的是寫(xiě)入的記錄數(shù)（以下用的是自己業(yè)務(wù)場(chǎng)景數(shù)據(jù)）
　　public int downLoadToExcel(OutputStream outputStream,List<PaimaiMoneyVO> paimaiMoneyVOList) {
　　　　　//文檔對(duì)象
  HSSFWorkbook wb = new HSSFWorkbook();
  int rowNum = 0;
  Sheet sheet = wb.createSheet("excel的標(biāo)題");
  Row row0 = sheet.createRow(rowNum++);
　　　　//因?yàn)閳?chǎng)景不同，titil不同，可以在外面寫(xiě)成數(shù)組當(dāng)參數(shù)傳進(jìn)來(lái)
  row0.createCell(0).setCellValue("第一列屬性名");
  row0.createCell(1).setCellValue("第二列屬性名");
  row0.createCell(2).setCellValue("第三列屬性名");
  row0.createCell(3).setCellValue("第四列屬性名");
  row0.createCell(4).setCellValue("第五列屬性名");
  row0.createCell(5).setCellValue("第六列屬性名");
　　　　 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("升價(jià)拍"); 
    row.createCell(5).setCellValue(bidder);
   }
  }
  try {
   wb.write(outputStream);
   LogEnum.LAW_WARE.info("表數(shù)據(jù)寫(xiě)入到excel表成功,一共寫(xiě)入了"+(rowNum - 1)+"條數(shù)據(jù)");
   outputStream.close();
  } catch (IOException e) {
   LogEnum.LAW_WARE.error("流關(guān)閉異常！", e);
  } finally {
   if (outputStream != null) {
    try {
     outputStream.close();
    } catch (IOException e) {
     LogEnum.LAW_WARE.error("流關(guān)閉異常！", e);
    }
   }
  }
  return rowNum - 1;
 }

2.“工具類(lèi)”寫(xiě)好后，下面就開(kāi)始使用它了，從上面的函數(shù)參數(shù)可以看到，我們需要傳過(guò)去兩個(gè)對(duì)象，一個(gè)是輸出流OutPutStream，通過(guò)流的方式把excel想要到瀏覽器，

另外一個(gè)就是我們需要導(dǎo)出的對(duì)象數(shù)組，好了，不解釋太多，看代碼。（下面的方法寫(xiě)在action層，通過(guò)struts.xml配置訪(fǎng)問(wèn)即可實(shí)現(xiàn)下載）

public void exportBail(){
  this.fileName = "excel文件名";
  try {
   List<PaimaiMoneyVO> paimaiMoneyVOList = new ArrayList<>();
　　　　　　//下面是我的業(yè)務(wù)場(chǎng)景獲取對(duì)象數(shù)組
   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&#63;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();//清空輸出流
   //下面是對(duì)中文文件名的處理
   response.setCharacterEncoding("UTF-8");//設(shè)置相應(yīng)內(nèi)容的編碼格式
　　　　　　　//解析瀏覽器
   final String userAgent = request.getHeader("USER-AGENT").toLowerCase();
   if(userAgent.contains("firefox")){ //火狐瀏覽器
    fileName = new String(fileName.getBytes(), "ISO8859-1");
   }else{
    fileName = URLEncoder.encode(fileName, "UTF-8"); //其他瀏覽器
　　　　　　　　　 fileName = fileName.Replace("+", "%20"); //encode后替換，解決空格問(wèn)題（其中%20是空格在UTF-8下的編碼 ，如果不這么寫(xiě)，瀏覽器會(huì)用+代替空格）
   }
   response.setHeader("Content-Disposition", "attachment;filename=" +fileName + ".xls");//指定輸出文件名
   response.setContentType("application/msexcel");//定義輸出類(lèi)型
   int rouNum = ensurePriceListToExcel(outputStream,paimaiMoneyVOList);
   LogEnum.LAW_WARE.info("【RiseAuctionAction.downLoadEnsurePriceExcel】導(dǎo)出成功,一共更新了{(lán)"+rouNum+"}條記錄");
  } catch (Exception e) {
   LogEnum.LAW_WARE.error("【RiseAuctionAction.downLoadEnsurePriceExcel】導(dǎo)出失敗,error is {}", e);
  }
 }

三、拓展（詳細(xì)的工具類(lèi)開(kāi)發(fā)）

如果你覺(jué)得上面寫(xiě)的太簡(jiǎn)單了，可以繼續(xù)往下看，我把它整理出了“萬(wàn)能”的工具類(lèi)，供大家參考。

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();
  //標(biāo)題
  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( "第一頁(yè)");
   sheet.setDefaultColumnWidth(COLUMN_WIDTH);
   sheet.setDefaultRowHeight(ROW_HEIGHT);
   //標(biāo)題
   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+ "條數(shù)據(jù)， NoSuchMethodException 反射錯(cuò)誤！";
      LOG.error(errorMsg,e);
      result.addDefaultModel(errorMsg);
      return result;
     } catch (IllegalAccessException e) {
      String errorMsg = field.getName() +"字段，第"+ index+ "條數(shù)據(jù)， IllegalAccessException ";
      LOG.error(errorMsg,e);
      result.addDefaultModel(errorMsg);
      return result;
     } catch (InvocationTargetException e) {
      String errorMsg = field.getName() +"字段，第"+ index+ "條數(shù)據(jù)， InvocationTargetException ";
      LOG.error(errorMsg,e);
      result.addDefaultModel(errorMsg);
      return result;
     }
    }
   }
  }
  try {
   workbook.write(out);
   result.setSuccess(true);
   return result;
  } catch (IOException e) {
   String errorMsg = "將導(dǎo)出數(shù)據(jù)寫(xiě)入輸出流失敗!";
   LOG.error("將導(dǎo)出數(shù)據(jù)寫(xiě)入輸出流失?。?",e);
   result.addDefaultModel(errorMsg);
   return result;
  }finally {
   try {
    out.close();
   } catch (IOException e) {
    String errorMsg = "關(guān)閉輸出流異常!";
    LOG.error("關(guān)閉輸出流異常！ ",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{
   //得到需要轉(zhuǎn)換的列名
   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("實(shí)體類(lèi)中無(wú)需要導(dǎo)出的字段!");
    result.addDefaultModel("實(shí)體類(lèi)中無(wú)需要導(dǎo)出的字段！");
    return result;
   }
   fieldArr = fieldList.toArray(new Field[fieldList.size()]);
  }catch(Exception e){
   LOG.error("數(shù)據(jù)拼裝異常!");
   result.addDefaultModel("數(shù)據(jù)拼裝異常!");
   return result;
  }
  //生成excel
  GenerateExcel ge = new GenerateExcel();
  return ge.export(titles,fieldArr,clazz,sourceList,out,false);
 }

}

看完上述內(nèi)容，你們掌握利用java如何實(shí)現(xiàn)把對(duì)象數(shù)組導(dǎo)出從Excel文件的方法了嗎？如果還想學(xué)到更多技能或想了解更多相關(guān)內(nèi)容，歡迎關(guān)注億速云行業(yè)資訊頻道，感謝各位的閱讀！

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