使用POI进行Excel文件下载的示例工程

说明：
1.下载http://www.apache.org/dyn/closer.cgi/poi/release/bin/poi-bin-3.7-20101029.zip后，将poi-3.7目录下的jar包放入lib目录， 再将此工程载入Eclipse/MyEclipse即可。
2.界面中文本框供输出数据量用，在我的T410上测试数据量在3.5W~3.6W之间，再多就报java.lang.OutOfMemoryError错误。
3.主要代码如下：

Sevlet代码：

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />-->package com.heyang.action;


import java.io.BufferedOutputStream;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;

import com.heyang.service.DownloadService;

/**
 * POI下载的Servlet
 * @author heyang
 *
 */
public class DownloadServlet extends HttpServlet {
    private static final long serialVersionUID = 56890894234786L;
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, java.io.IOException {
        String fileName="download.xls";
        response.setHeader("Content-disposition", "attachment; filename="+fileName);// 设定输出文件头   
        response.setContentType("application/msexcel");// 定义输出类型 
        
        try{
            int rowCount=Integer.parseInt(request.getParameter("rowCount"));
            
            // 表头行
            String[] headers=new String[]{"更新ID","账期","基站编号","基站名称","站点状态","部门名称","站点类型","占用类型","预提(元)","未核销金额","上期未核销","开始月份","结束月份","上期抄表数","本期抄表数","电价","电量","本期报账(元)","补提(元)","预提汇总(元)","成本中心","专业","本期报账单号","基站类别","线损"};
            DownloadService service=new DownloadService();

            HSSFWorkbook workbook=service.generateWorkbook(rowCount, headers.length);

            ServletOutputStream out = response.getOutputStream();
            BufferedOutputStream bos = new BufferedOutputStream(out);        
            workbook.write(bos);
            bos.flush();
            bos.close();
            
        }catch(Exception ex){
            ex.printStackTrace();
        }
        
        return ;
    }
        
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, java.io.IOException {
        doPost(request, response);
    }
}

Service代码：

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />-->package com.heyang.service;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;


/**
 * 下载服务类
 * 
 * @author heyang
 *
 */
public class DownloadService{
    /**
     * 生成工作簿对象
     * @param rowCount
     * @param columnCount
     * @return
     */
    public HSSFWorkbook generateWorkbook(int rowCount,int columnCount) throws Exception{
        HSSFWorkbook workbook = new HSSFWorkbook(); //产生工作簿对象
        HSSFSheet sheet = workbook.createSheet(); //产生工作表对象
        String value=null;
        
        HSSFRow row = null;
        HSSFCell cell = null;
        
        for(int i=0;i<rowCount;i++){
            row = sheet.createRow(i);//创建一行
            
            for(int j=0;j<columnCount;j++){
                value=""+i+","+j;
                
                cell = row.createCell(j);
                cell.setCellValue(value);
                
                cell = null;
            }
            
            row = null;
        }
        
        row = null;
        cell = null;
        
        return workbook;
    }
}