POI导出excel的三种方式

原文链接:https://www.cnblogs.com/zhaoblog/p/7661245.html

poi导出excel最常用的是第一种方式HSSFWorkbook，不过这种方式数据量大的话会产生内存溢出问题，SXSSFWorkbook是一种大数据量导出格式，csv是另一种excel导出的一种轻快的实现。

先介绍一下这三种格式的特点

1 HSSFWorkbook  excel文件底层是txt实现，我们经常见到的excel都是这种实现的。

2 SXSSFWorkbook  excel文件底层是xml实现，同样的数据量，大约是第一种的1/6-1/4之间

3 csv 这个比较新潮，数据量应该更小，可以百度。

一 HSSFWorkbook 实现

Map dataMap = service.AssignMiddleExcel(page);
ObjectExcelView erv = new ObjectExcelView("逾期客户表");             //执行excel操作
mv = new ModelAndView(erv,dataMap);
//dataMap 是个map ,包含两个键值对  一个是标题列 
Map dataMap = new HashMap();
      List titles = new ArrayList();
      
      titles.add("借款人姓名");        //1
      titles.add("身份证号");         //2
      titles.add("借款人手机号");
   dataMap.put("titles", titles);
 // 这是标题列
//vpd是个map
vpd.put("var1", userList.get(i).getString("realName"));     //1
vpd.put("var2", userList.get(i).getString("contIdCard"));   //2
vpd.put("var3", userList.get(i).getString("telephone"));    //3
List varList = new ArrayList();
//PageData就是个HashMap
varList.add(vpd);
dataMap.put("varList", varList);
//这就是dataMap的由来

public class ObjectExcelView extends AbstractExcelView{
   
   private String fileName;
   
   public ObjectExcelView(){
      
   }
   public ObjectExcelView(String fileName){
      
      this.fileName = fileName;
   }
   
   @Override
   protected void buildExcelDocument(Map model,
         HSSFWorkbook workbook, HttpServletRequest request,
         HttpServletResponse response) throws Exception {
      // TODO Auto-generated method stub
      //String fileName = "逾期客户表-待催收";
      HSSFSheet sheet;
      HSSFCell cell;
      response.setContentType("application/x-download");//下面三行是关键代码，处理乱码问题  
      response.setCharacterEncoding("utf-8");  
      response.setHeader("Content-Disposition", "attachment;filename="+new String(fileName.getBytes("gbk"), "iso8859-1")+".xls");  
      sheet = workbook.createSheet("sheet1");

      List titles = (List) model.get("titles");
      int len = titles.size();
      HSSFCellStyle headerStyle = workbook.createCellStyle(); //标题样式
      headerStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
      headerStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);
      HSSFFont headerFont = workbook.createFont();   //标题字体
      headerFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
      headerFont.setFontHeightInPoints((short)11);
      headerStyle.setFont(headerFont);
      short width = 20,height=25*20;
      sheet.setDefaultColumnWidth(width);
      for(int i=0; i//设置标题
         String title = titles.get(i);
         cell = getCell(sheet, 0, i);
         cell.setCellStyle(headerStyle);
         setText(cell,title);
      }
      sheet.getRow(0).setHeight(height);

      HSSFCellStyle contentStyle = workbook.createCellStyle(); //内容样式
      contentStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
      List varList = (List) model.get("varList");
      int varCount = varList.size();
      for(int i=0; i){
         PageData vpd = varList.get(i);
         for(int j=0;j){
            String varstr = vpd.getString("var"+(j+1)) != null ? vpd.getString("var"+(j+1)) : "";
            cell = getCell(sheet, i+1, j);
            cell.setCellStyle(contentStyle);
            setText(cell,varstr);
         }

      }

   }

}

 

二 SXSSFWorkbook  

@RequestMapping("/excel111")
public Object  exportExcel(Page page,HttpServletRequest request,HttpServletResponse response){
    PageData pd = new PageData();
    pd = this.getPageData();
    try{
        //检索条件===========
        PageData pageData = service.setPdWithTrim(this.getPageData());
        page.setPd(pageData);
        //检索条件===========
        Map dataMap = service.AssignMiddleExcel(page);
        OutputStream outputStream = response.getOutputStream();
        String sheetName = "逾期客户表";
        List list = (List)dataMap.get("titles");
        String[] headers = new  String[list.size()];
        for(int i = 0;i){
            headers[i]=list.get(i);
        }
        List dataList = new ArrayList<>();
        List varList = new ArrayList();
        varList =  (List)dataMap.get("varList");

        varList.forEach(e ->{
            List