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[Java教程]POI实现Excel文件上传下载,读/写数据库(poi)

poi是Apache基金会的开放源码函式库,提供API给Java程式对Microsoft Office格式档案读和写的功能。这里是对Excel的读取下载/上传实现;在一些需要导入导出数据时感觉比较有用;曾经在CRM中实现下载/上传联系人信息,不过当时不是自己负责的,总体来说下载比较容易实现,上传由于格式必须与数据库字段对应,显得有些麻烦;这里为了demo方便,没有与数据库交互,使用的是Servlet实现;

依赖包:

1.commons-fileupload

2.commons-io

3.poi

下载地址http://poi.apache.org/  http://commons.apache.org/

下面是代码实现

web.
<??>
<web-app version="2.5"
="http://java.sun.com/
="http://www.w3.org/2001/
xsi:schemaLocation="http://java.sun.com/ http://java.sun.com/>
<servlet>
<servlet-name>PoiServlet</servlet-name>
<servlet-class>com.wf.web.PoiServlet</servlet-class>
</servlet> <servlet-mapping>
<servlet-name>PoiServlet</servlet-name>
<url-pattern>/poitest.jspx</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
显示页面index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>POI测试</title>
</head>

<body>
<a href="poitest.jspx?_m=poi_down">下载</a><br>
<form action="poitest.jspx?_m=poi_upload" method="post" enctype="multipart/form-data">
<input type="file" name="file">
<input type="submit" value="submit">
</form>
</body>
</html>
Servlet端Java代码PoiServlet.java
package com.wf.web;import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;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.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
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;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;public class PoiServlet extends HttpServlet { private static final long serialVersionUID = 1L; public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String method = request.getParameter("_m");
if("poi_down".equals(method)){
poi_down(request,response);
}else if("poi_upload".equals(method)){
poi_upload(request,response);
}

} private void poi_upload(HttpServletRequest request,
HttpServletResponse response) {
if(ServletFileUpload.isMultipartContent(request)){
DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setSizeThreshold(1024*512);
factory.setRepository(new File("D:/tempload"));
ServletFileUpload fileUpload=new ServletFileUpload(factory);
fileUpload.setFileSizeMax(10*1024*1024);//设置最大文件大小
try {
@SuppressWarnings("unchecked")
List<FileItem> items=fileUpload.parseRequest(request);//获取所有表单
for(FileItem item:items){
//判断当前的表单控件是否是一个普通控件
if(!item.isFormField()){
//是一个文件控件时
String excelFileName = new String(item.getName().getBytes(), "utf-8"); //获取上传文件的名称
//上传文件必须为excel类型,根据后缀判断(xls)
String excelContentType = excelFileName.substring(excelFileName.lastIndexOf(".")); //获取上传文件的类型
System.out.println("上传文件名:"+excelFileName);
System.out.println("文件大小:"+item.getSize());
System.out.println("\n---------------------------------------");
if(".xls".equals(excelContentType)){
POIFSFileSystem fileSystem = new POIFSFileSystem(item.getInputStream());
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem);
HSSFSheet sheet = workbook.getSheetAt(0);
int rows = sheet.getPhysicalNumberOfRows();
for (int i = 0; i < rows; i++) {
HSSFRow row = sheet.getRow(i);
int columns = row.getPhysicalNumberOfCells();
for (int j = 0; j < columns; j++) {
HSSFCell cell = row.getCell(j);
String value = this.getCellStringValue(cell);
System.out.print(value + "|");
}
System.out.println("\n---------------------------------------");
}
System.out.println("success!");
}else{
System.out.println("必须为excel类型");
}
//顺便把文件保存到硬盘,防止重名
// String newName=new SimpleDateFormat("yyyyMMDDHHmmssms").format(new Date());
// File file = new File("d:/upload");
// if(!file.exists()){
// file.mkdir();
// }
// item.write(new File("d:/upload/"+newName+excelContentType));
response.sendRedirect("index.jsp");
}
}
}catch (Exception e) {
e.printStackTrace();
}
}
} private void poi_down(HttpServletRequest request,
HttpServletResponse response) {
response.setContentType("application/vnd.ms-excel;charset=UTF-8");
response.setHeader("Content-Disposition", "attachment;filename=data.xls");

ServletOutputStream stream = null;
try {
stream = response.getOutputStream();
} catch (IOException e1) {
e1.printStackTrace();
}
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFCellStyle style = workbook.createCellStyle();
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);//左右居中样式

HSSFSheet sheet = workbook.createSheet("我的联系人");
sheet.setColumnWidth(0, 2000);
sheet.setColumnWidth(1, 5000);
//创建表头(第一行)
HSSFRow row = sheet.createRow(0);
//列
HSSFCell cell = row.createCell(0);
cell.setCellValue("姓名");
cell.setCellStyle(style);
HSSFCell cell2 = row.createCell(1);
cell2.setCellValue("电话");
cell2.setCellStyle(style);

//创建数据行
for(int i =1;i<=20;i++) {
HSSFRow newrow = sheet.createRow(i);
newrow.createCell(0).setCellValue("tom"+i);
newrow.createCell(1).setCellValue("135816****"+i);
}
try {
workbook.write(stream);
System.out.println("下载成功");
stream.flush();
stream.close();
} catch (Exception e) {
e.printStackTrace();
}

} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
//获取单元格内不同类型值
public String getCellStringValue(HSSFCell cell) {
String cellValue = "";
switch (cell.getCellType()) {
case HSSFCell.CELL_TYPE_STRING:
cellValue = cell.getStringCellValue();
if(cellValue.trim().equals("")||cellValue.trim().length()<=0)
cellValue=" ";
break;
case HSSFCell.CELL_TYPE_NUMERIC:
cellValue = String.valueOf(cell.getNumericCellValue());
break;
case HSSFCell.CELL_TYPE_FORMULA:
cell.setCellType(HSSFCell.CELL_TYPE_NUMERIC);
cellValue = String.valueOf(cell.getNumericCellValue());
break;
case HSSFCell.CELL_TYPE_BLANK:
cellValue=" ";
break;
case HSSFCell.CELL_TYPE_BOOLEAN:
break;
case HSSFCell.CELL_TYPE_ERROR:
break;
default:
break;
}
return cellValue;
}
}

上传后的Excel已经读入内存,可以与数据库交互,上传字段与数据库字段必须一致,否则会报错;实际项目一般都是先下载Excel模板之后,用户填写模板上传,模板中定义好数据格式;当然避免不了随便把一个文件后缀改为xls了