Java导出Excel文件（jxl.jar版）（详细解读）

import jxl.*;
import jxl.write.*;

public class ExportData
{
public void exportProduct()
{
try
{
//类login(javabean)的managed-bean-scope属性设置成session，这样可以调用login中当前用户的id。这个非常有用。
login me = (login) FacesContext.getCurrentInstance().getExternalContext().getSessionMap().get("login");
String userId = String.valueOf(me.getID_());
//设置导出文件在服务器上的存储路径，getBasedir()和getSeparator()根据服务器OS来判断当前路径和连接符，Windows 和Linux不一样。
String storedir = getBasedir() + userId + getSeparator();
//System.out.println("storedir:" + storedir);
//System.out.println("main.isDirExists(storedir):" + main.isDirExists(storedir));
//如果storedir文件不存在，就创建它
if(main.isDirExists(storedir))
{
storedir = storedir + "exportExcel.xls";
File file = new File(storedir);
if(file.exists())
file.delete();
//创建一个excel文件
jxl.write.WritableWorkbook wwb = Workbook.createWorkbook(new File(storedir));
//创建一个工作簿
jxl.write.WritableSheet ws = wwb.createSheet("data", 0);
//定义excel的文本单元格
jxl.write.Label label;
//定义excel的数值单元格
jxl.write.Number number;
//格式化数值
jxl.write.NumberFormat nf = new jxl.write.NumberFormat("#.####");
jxl.write.WritableCellFormat wcNf = new jxl.write.WritableCellFormat(nf);
//从0开始，设置列标题
label = new jxl.write.Label(0,0, "物品编码");
ws.addCell(label);
label = new jxl.write.Label(1,0, "物品描述");
ws.addCell(label);
label = new jxl.write.Label(2,0, "库存数量");
ws.addCell(label);
label = new jxl.write.Label(3,0, "入库日期");
ws.addCell(label);
label = new jxl.write.Label(4,0, "在库天数");
ws.addCell(label);
label = new jxl.write.Label(5,0, "在库月份");
ws.addCell(label);
label = new jxl.write.Label(6,0, "入库数量");
ws.addCell(label);
label = new jxl.write.Label(7,0, "成本");
ws.addCell(label);
label = new jxl.write.Label(8,0, "总成本");
ws.addCell(label);
main.oracleSession.clear();
//循环提取表中的数据
Query query = main.oracleSession.getNamedQuery("masQuery.selectProductStock");
List list = query.list();
String pItemCode,pItemDesc,pQuantity,pTranDate,pDays,pMonths,pTranQuantity,pCost,pTotalCost;
for(int i=0;i<list.size();i++)
{
pItemCode=pItemDesc=pQuantity=pTranDate=pDays=pMonths=pTranQuantity=pCost=pTotalCost="";
Object obj[] = (Object[])list.get(i);
if(obj[0]!=null)
pItemCode = String.valueOf(obj[0]);
if(obj[1]!=null)
pItemDesc = String.valueOf(obj[1]);
if(obj[2]!=null)
pQuantity = String.valueOf(obj[2]);
if(obj[3]!=null)
pTranDate = String.valueOf(obj[3]);
if(obj[4]!=null)
pDays = String.valueOf(obj[4]);
if(obj[5]!=null)
pMonths = String.valueOf(obj[5]);
if(obj[6]!=null)
pTranQuantity = String.valueOf(obj[6]);
if(obj[7]!=null)
pCost = String.valueOf(obj[7]);
if(obj[8]!=null)
pTotalCost = String.valueOf(obj[8]);
//写入数据行
label = new jxl.write.Label(0,i+1, pItemCode);
ws.addCell(label);
label = new jxl.write.Label(1,i+1, pItemDesc);
ws.addCell(label);
//这一个是数值型数据，没有格式化数据
number = new jxl.write.Number(2,i+1, Integer.valueOf(pQuantity));
ws.addCell(number);
label = new jxl.write.Label(3,i+1, pTranDate);
ws.addCell(label);
number = new jxl.write.Number(4,i+1, Integer.valueOf(pDays));
ws.addCell(number);
number = new jxl.write.Number(5,i+1, Integer.valueOf(pMonths));
ws.addCell(number);
number = new jxl.write.Number(6,i+1, Integer.valueOf(pTranQuantity));
ws.addCell(number);
//这一个是数值型数据，格式化数据，保留4位小数
number = new jxl.write.Number(7,i+1, Float.valueOf(pCost), wcNf);
ws.addCell(number);
number = new jxl.write.Number(8,i+1, Float.valueOf(pTotalCost), wcNf);
ws.addCell(number);
}
//关闭文件
wwb.write();
wwb.close();
myMain my = new myMain();
//弹出下载框
my.mDownload(storedir);
}
}catch(Exception ex){ex.printStackTrace();}
}
}