导出Excel通用工具类

导出Excel的两种方法：

一，POI

导入poi包

poi-3.11-beta3-20141111.jar

 /**
 *
 */
 package com.car.ots.mpckp.utils;

 import java.io.OutputStream;
 import java.net.URLEncoder;
 import java.util.List;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import org.apache.commons.beanutils.BeanUtils;
 import org.apache.poi.hssf.usermodel.HSSFCell;
 import org.apache.poi.hssf.usermodel.HSSFCellStyle;
 import org.apache.poi.hssf.usermodel.HSSFRow;
 import org.apache.poi.hssf.usermodel.HSSFSheet;
 import org.apache.poi.hssf.usermodel.HSSFWorkbook;

 /**
 * @author cora.guo
 *
 */
 public class ExportUtils {

 public static void createExcel(HttpServletRequest req,
 HttpServletResponse resp, List<Object> datas, String sheetName,
 List<String> headers, List<String> colunmValueNames)
 throws Exception {
 OutputStream out = null;
 try {
 // 第一步，创建一个webbook，对应一个Excel文件
 resp.setContentType("application/vnd.ms-excel");
 resp.setCharacterEncoding("UTF-8");
 if (req.getHeader("User-Agent").toLowerCase().indexOf("msie") != -) {
 resp.setHeader("Content-Disposition", "attachment;filename="
 + URLEncoder.encode(sheetName, "utf-8") + ".xls");
 } else {
 resp.setHeader("Content-Disposition", "attachment;filename="
 + new String(sheetName.getBytes("utf-8"), "ISO-8859-1")
 + ".xls");
 }
 resp.setHeader("Cache-Control", "max-age=0");
 HSSFWorkbook wb = new HSSFWorkbook();

 // 第二步，在webbook中添加一个sheet,对应Excel文件中的sheet
 HSSFSheet sheet = wb.createSheet(sheetName);
 // 第三步，在sheet中添加表头第0行,注意老版本poi对Excel的行数列数有限制short
 HSSFRow row = sheet.createRow();
 // 第四步，创建单元格，并设置值表头 设置表头居中
 HSSFCellStyle style = wb.createCellStyle();
 // 创建居中样式
 style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
 HSSFCell cell = null;
 if (headers != null && headers.size() > ) {
 for (int i = ; i < headers.size(); i++) {
 cell = row.createCell(i);
 cell.setCellValue(headers.get(i));
 cell.setCellStyle(style);
 }
 }
 // 第五步，写入实体数据 实际应用中这些数据从数据库得到，
 if (datas != null && datas.size() != ) {
 for (int r = ; r < datas.size(); r++) {
 Object obj = datas.get(r);
 row = sheet.createRow(r+);
 if (colunmValueNames != null
 && colunmValueNames.size() != ) {
 for (int j = ; j < colunmValueNames.size(); j++) {
 String name = colunmValueNames.get(j);
 String value = BeanUtils.getProperty(obj, name);
 // 创建单元格,设置值
 cell = row.createCell(j);
 cell.setCellStyle(style);
 cell.setCellValue(value);
 }
 }
 }
 }
 out = resp.getOutputStream();
 wb.write(out);
 } catch (Exception e) {
 // TODO Auto-generated catch block
 throw new Exception(e);
 } finally {
 out.close();
 }
 }
 }

二，JXl

导入包

 package com.car.ots.uis.utils;

 import java.net.URLEncoder;
 import java.util.List;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import jxl.Workbook;
 import jxl.format.Alignment;
 import jxl.format.VerticalAlignment;
 import jxl.write.Label;
 import jxl.write.WritableCellFormat;
 import jxl.write.WritableFont;
 import jxl.write.WritableSheet;
 import jxl.write.WritableWorkbook;

 import org.apache.commons.beanutils.BeanUtils;

 public class ExportUtil {
   public static void export(HttpServletRequest req, HttpServletResponse resp, List<Object> datas,
       String sheetName, List<String> headers, List<String> colunmValueNames) throws Exception {
     // 写入excel
     WritableWorkbook wb = null;
     WritableSheet ws = null;
     Label label = null;

     try {
       resp.setContentType("application/vnd.ms-excel");
       resp.setCharacterEncoding("UTF-8");
       if (req.getHeader("User-Agent").toLowerCase().indexOf("msie") != -) {
         resp.setHeader("Content-Disposition",
             "attachment;filename=" + URLEncoder.encode(sheetName, "utf-8") + ".xls");
       } else {
         resp.setHeader("Content-Disposition",
             "attachment;filename=" + new String(sheetName.getBytes("utf-8"), "ISO-8859-1") + ".xls");
       }
       resp.setHeader("Cache-Control", "max-age=0");
       wb = Workbook.createWorkbook(resp.getOutputStream());

       ws = wb.createSheet(sheetName, );

       WritableFont bold_font = new WritableFont(WritableFont.ARIAL, , WritableFont.BOLD);
       WritableCellFormat f = new WritableCellFormat(bold_font);
       f.setVerticalAlignment(VerticalAlignment.CENTRE);
       f.setAlignment(Alignment.CENTRE);
       if(headers!=null&headers.size()!=){
           for (int i = ; i < headers.size(); i++) {
               ws.setColumnView(i, );
               label = new Label(i, , headers.get(i), f);
               ws.addCell(label);
           }
       }

       WritableFont nobold_font = new WritableFont(WritableFont.ARIAL, , WritableFont.NO_BOLD);
       f = new WritableCellFormat(nobold_font);
       f.setVerticalAlignment(VerticalAlignment.CENTRE);
       f.setAlignment(Alignment.CENTRE);
       if(datas!=null&&datas.size()!=){
           for (int r = ; r < datas.size(); r++) {
               Object obj = datas.get(r);
               if (colunmValueNames!=null&&colunmValueNames.size()!=) {
                   for (int j = ; j < colunmValueNames.size(); j++) {
                       String name = colunmValueNames.get(j);
                       String value = BeanUtils.getProperty(obj, name);
                       label = new Label(j, r + , value, f);
                       ws.addCell(label);
                   }
             }
           }
       }
       wb.write();
     } catch (Exception e) {
       throw new Exception(e);
     } finally {
       wb.write();
       wb.close();

     }
   }

 }

两者区别：

POI为apache公司的一个子项目,主要是提供一组操作windows文档的Java API
JavaExcel俗称jxl是一开放源码项目，通过它开发人员可以读取Excel文件的内容、创建新的Excel文件、更新已经存在的Excel文件。使用该API非Windows操作系统也可以通过纯Java应用来处理Excel数据表。因为是使用Java编写的，所以我们在Web应用中可以通过JSP、Servlet来调用API实现对Excel数据表的访问。

JVM虚拟机内存消耗的情况：

数据量3000条数据,每条60列.JVM虚拟机内存大小64M.
使用POI:运行到2800条左右就报内存溢出.
使用JXL:3000条全部出来,并且内存还有21M的空间.
可想而知,在对内存的消耗方面差距还是挺大的.
也许是由于JXL在对资源回收利用方面做的不错.

效率方面：

也是基于大数据量而言的,数据量小的话基本上差别不大,也不难被发觉.但是大的数据量,POI消耗的JVM内存远比JXL消耗的多.但相比提供的功能的话,JXL又相对弱了点.所以如果要实现的功能比较复杂的情况下可以考虑使用POI,但如果只想生成一些大数据量可以考虑使用JXL