使用POI操作Excel文件（二）

针对使用POI操作Excel文件，可以参考：《POI读取EXCEL教程》http://julycn.javaeye.com/blog/107341

下面为在struts1.x下使用POI生成Excel文件并下载。

大概过程如下：创建HSSFWorkbook——在刚创建的HSSFWorkbook下创建sheet——在刚创建的sheet下创建row——在刚创建的row下创建Cell——在刚创建的Cell中填入数据——把创建的HSSFWorkbook加入到OutputStream中。

在实际的开发中，经常会碰到以Excel形式导出数据库中的数据，完成此功能，可以在此程序的基础上把写入Cell中的数据改为写入数据库中的数据即可。

在此程序中使用了struts中的action做为控制器，所以相应的视图JSP文件内容为空即可。

为了方便阅读，全部代码如下，完整工程可到我的资源里下载：http://download.csdn.net/source/765876

//DownloadAction.java

import java.io.OutputStream;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

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;

import org.apache.struts.action.Action;

import org.apache.struts.action.ActionForm;

import org.apache.struts.action.ActionForward;

import org.apache.struts.action.ActionMapping;

public class DownloadAction extends Action {

@Override

public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {

//create HSSFWorkbook

HSSFWorkbook workbook = new HSSFWorkbook();

//create HSSFSheet named user

HSSFSheet sheet = workbook.createSheet("user");

for(int i=0;i<5;i++){

//create row

HSSFRow row = sheet.createRow(i);

for(int j=0;j<3;j++){

//create cell

HSSFCell cell = row.createCell((short)(j));

//filled cell

cell.setCellValue(i+"/"+j);

}

}

//set response content type

response.setContentType("application/vnd.ms-excel");

//set the name of download file

response.addHeader("Content-Disposition","attachment;filename=user.xls");

//get response stream

OutputStream out=response.getOutputStream();

//add workbook to OutpustStream

workbook.write(out);

out.close();

return mapping.findForward("success");

}

}

<!--download.jsp(but it is blank.)-->

下面的为配置文件：web.xml and struts-config.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.4"

xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>

<servlet-name>action</servlet-name>

<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>

<init-param>

<param-name>cofig</param-name>

<param-value>/WEB-INF/struts-config.xml</param-value>

</init-param>

<load-on-startup>0</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>action</servlet-name>

<url-pattern>*.do</url-pattern>

</servlet-mapping>

</web-app>

<?xml version="1.0" encoding="ISO-8859-1" ?>

<!DOCTYPE struts-config PUBLIC

"-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"

"http://struts.apache.org/dtds/struts-config_1_3.dtd">

<struts-config>

<form-beans>

</form-beans>

<action-mappings>

<action path="/download" type="DownloadAction">

<!-- download.jsp is a blank file,but it exist -->

<forward name="success" path="/download.jsp"></forward>

</action>

</action-mappings>

</struts-config>