Excel表格文件的上传和下载，java中涉及到文件肯定会有io流的知识。
而excel文件就要涉及到poi技术，而excel的版本包括：2003-2007和2010两个版本， 即excel的后缀名为：xls和xlsx。
这里我是按照正规的项目流程做的案例，所以可能会比网上的一些Demo复杂一些。不过文件的上传和下载基本都是一套固定的流程，只是每个人的实现方式不太相同。
数据库我用的是MySql。
下面是我的项目目录：
按照正常的项目做了分层处理，文件上传的业务我放到了service处理，而文件下载业务还在controller层。
对前端请求处理，我分成了两个方法都放在HandleExcelController里面，这个类继承了BaseExcelController,基本的文件操作处理在BaseExcelController里面。
BaseExcelController继承了BaseController，BaseController类是所有controller的父类，这里用到的不太多，这个类封装了response返回值等的处理等一些方法。
项目中除了springMVC和mybatis的jar包之外还引入了：
上传和下载excel文件：
1、创建需要上传的excel文件，为了简化，我这里只写了四列，即四个字段
2、创建jsp页面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Excel文件处理</title>
<script type="text/javascript" src="<c:url value='/res/js/jquery.js'/>"></script>
<script>
$(function(){
var $wrap = $(".wrap");
var find = function(str){
return $wrap.find(str);
}
var getJname = function(name){
return find("input[name='"+name+"']");
}
getJname("Upload").click(function(){
var form = new FormData(document.getElementById("tf"));
$.ajax({
url:"<c:url value='/File/UploadExcel'/>",
type:"post",
data:form,
dataType:"json",
processData:false,
contentType:false,
success:function(data){
//window.clearInterval(timer);
if(data.success == "success"){
alert("提交文件成功,已将数据存入数据库");
}
},
error:function(e){
alert("错误！");
//window.clearInterval(timer);
}
});
})
getJname("Download").click(function(){
$.post("<c:url value='/File/DownLoadExcel'/>",{"id":"3"},function(data){
//alert("下载文件成功");
},"json")
}) })
</script>
</head> <body>
<div class="wrap">
<form id="tf">
<p>
<input type="file" name="file" value="选择文件"/>
Excel文件上传：<input type="button" name="Upload" value="upload"/>
</p>
<p>
Excel文件下载：<input type="button" name="Download" value="updown"/>
</p>
</form>
</div>
</body>
</html>
3、依次创建controller、service、domain、mapper层，注意它们的依赖关系
1）、controller层的处理，在HandleExcelController里面注入BaseExcelService。因为只是做个示范，所欲我这里将泛型固定为Students类
BaseExcelController代码：
package cn.wangze.controller; import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.List; import javax.servlet.http.HttpServletResponse; import org.apache.commons.lang.StringUtils;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.usermodel.HSSFPalette;
import org.apache.poi.hssf.usermodel.HSSFRichTextString;
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.hssf.util.CellRangeAddress;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.web.multipart.MultipartFile; import cn.wangze.domain.Students; public class BaseExcelController extends BaseController{
//获取文件的路径
String separator = System.getProperty("file.separator"); //验证元素是否为空
@SuppressWarnings("all")
public boolean isEmpty(Object obj){
if(obj instanceof Object[]){
if(((Object[]) obj).length==0){
return true;
}
if(obj == null) return true;
if((String.valueOf(obj).trim()).length() == 0){
return true;
}
if(obj instanceof List){
if(((List) obj) == null || ((List)obj).size() == 0){
return true;
}
}
}
return false;
} /**
* 文件上传部分
* */
//验证文件
protected boolean checkPathName(String fileName,HttpServletResponse response){
//验证文件是否存在
if(isEmpty(fileName)){
sendError("上传文件不存在",response);
return false;
}
//验证文件是否是以xls或者xlsx做后缀的文件，如果不是就返回错误信息
if(!(StringUtils.endsWithIgnoreCase(fileName,".xls")||StringUtils.endsWithIgnoreCase(fileName, ".xlsx"))){
sendError("上传文件类型错误，请核对后重新上传?",response);
}
return true;
} //获取文件的sheet
protected Sheet getSheet(MultipartFile file,String path,String fileName) throws IllegalStateException, IOException{
//找到要存放到项目里面的路径，新建文件
File targetFile = new File(path, fileName);
targetFile.mkdirs();
if (targetFile.exists()) {
targetFile.delete();
file.transferTo(targetFile);
} else {
file.transferTo(targetFile);
}
//封装输入流,封装sheet里面的内容
InputStream is = null;
try{
is = new FileInputStream(path+separator+fileName);
//判断版本是否为Excel加强版
if(StringUtils.endsWithIgnoreCase(fileName, ".xls")){
return new HSSFWorkbook(is).getSheetAt(0);
}else if(StringUtils.endsWithIgnoreCase(fileName, ".xlsx")){
return new XSSFWorkbook(is).getSheetAt(0);
}
return null;
}
finally{
if(is != null){
is.close();
}
}
} /**
* 文件下载部分
* */
//根据传入的Sting值，判断生成在excel表的位置
private HSSFCellStyle getPublicStyle(HSSFWorkbook workbook,String key){
HSSFFont font = workbook.createFont();
HSSFCellStyle style = workbook.createCellStyle();
HSSFPalette customPalette = workbook.getCustomPalette();
customPalette.setColorAtIndex(HSSFColor.TEAL.index, (byte) 64, (byte) 148, (byte) 160);
customPalette.setColorAtIndex(HSSFColor.ORANGE.index, (byte) 170, (byte) 204, (byte) 204);
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);
if(key=="head"){
style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
font.setFontHeightInPoints((short)12);
font.setColor(HSSFColor.TEAL.index);
font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
style.setFont(font);
}
if(key=="title"){
font.setColor(HSSFColor.WHITE.index);
font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
style.setBorderLeft(HSSFCellStyle.BORDER_THIN);
style.setLeftBorderColor(HSSFColor.WHITE.index);
style.setBorderRight(HSSFCellStyle.BORDER_THIN);
style.setRightBorderColor(HSSFColor.WHITE.index);
style.setFont(font);
style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
style.setFillForegroundColor(HSSFColor.ORANGE.index);
style.setFillBackgroundColor(HSSFColor.ORANGE.index);
}
return style;
}
//创建head头信息
private void createHead(HSSFSheet sheet,HSSFCellStyle style,String[] title){
HSSFRow row1 = sheet.createRow(0);
HSSFCell cellTitle = row1.createCell(0);
cellTitle.setCellValue(new HSSFRichTextString(title[0]));
sheet.addMergedRegion(new CellRangeAddress(0,0,0,title.length-2));
cellTitle.setCellStyle(style);
}
//创建title信息
private void createTitle(HSSFSheet sheet,HSSFCellStyle style,String[] label,int columnNum){
HSSFRow row2 = sheet.createRow(1);
HSSFCell cell1 = null;
for(int n=0;n<columnNum;n++){
cell1 = row2.createCell(n);
cell1.setCellValue(label[n+1]);
cell1.setCellStyle(style);
}
}
//创建content数据信息
private void createContent(HSSFSheet sheet,HSSFCellStyle style,Collection<Students> list,int columnNum,String[] parameters){
int index= 0;
Iterator<Students> it = list.iterator();
while(it.hasNext()){
index++;
Students cash = it.next();
int num2 = parameters.length;
HSSFRow row = sheet.createRow(index+1);
initCells(style, num2,cash, parameters,row);
}
}
//验证是否为中文
public boolean checkChinese(String s){
int n=0;
boolean flag =false;
for(int i=0; i<s.length(); i++) {
n = (int)s.charAt(i);
flag=(19968 <= n && n <40623)?true:false;
}
return flag;
}
//将数据设置到excel表格内
public void initCells(HSSFCellStyle style, int columnNum, Students t,
String[] endContent, HSSFRow row3) {
for(int j=0;j<columnNum;j++){
HSSFCell cell = row3.createCell(j);
String fieldName = endContent[j];
try{
if(fieldName!="" && !checkChinese(fieldName)){
String getMethodName = "get" +fieldName.substring(0,1).toUpperCase()+fieldName.substring(1);
Class clazz = t.getClass();
Method getMethod = clazz.getMethod(getMethodName, new Class[]{});
String value = (String)getMethod.invoke(t, new Object[]{});
cell.setCellValue(value);
}else{
cell.setCellValue(fieldName);
}
cell.setCellStyle(style);
}catch(Exception e){
e.printStackTrace();
}
}
}
public void createEnd(HSSFSheet sheet,HSSFCellStyle style,int numText,int columnNum,Students t,String[] endContent){
HSSFRow row3 = sheet.createRow(numText+2);
initCells(style, columnNum, t, endContent, row3);
} //根据service查询到的数据，创建excel表并插入查询的数据信息
protected String getOutputName(List<Students> list, String path, String[] title, String[] parameters, Students t, String[] endContent)
throws IOException{
//根据传入的title数组的第一个值，设置文件名称
String filename = title[0]+"_"+ new SimpleDateFormat("yyyyMMdd").format(new Date())+".xls";
//输出流放到文件的本地位置
FileOutputStream fos = new FileOutputStream(path+separator+filename);
//列数，根据title的个数，除去第一个就是每列title的信息
int columnNum = title.length-1;
int numText = list.size();
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet();
sheet.setDefaultColumnWidth (20);
sheet.setDefaultRowHeight((short)400);
HSSFCellStyle contentStyle = this.getPublicStyle(workbook,"");
HSSFCellStyle titleStyle = this.getPublicStyle(workbook,"title");
HSSFCellStyle headerStyle = this.getPublicStyle(workbook,"head");
createHead(sheet,headerStyle,title);
createTitle(sheet,titleStyle,title,columnNum);
createContent(sheet,contentStyle,list,columnNum,parameters);
//createEnd(sheet,contentStyle,numText,columnNum,t,endContent);
workbook.write(fos);
fos.flush();
fos.close();
return filename;
}
}
HandleExcelController用来处理前端请求，代码如下：
package cn.wangze.controller; import java.io.File;
import java.util.List; import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession; import org.apache.commons.io.FileUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile; import cn.wangze.domain.Students;
import cn.wangze.service.BaseExcelService; @Controller
@RequestMapping("/File")
public class HandleExcelController extends BaseExcelController{
@Autowired
private BaseExcelService baseExcelService; @RequestMapping("/UploadExcel")
public void UploadExcel(MultipartFile file,HttpSession session,HttpServletResponse response) throws Exception{
//如果上传的文件不存在，抛出异常
if(file == null){
throw new Exception("文件不存在");
}
//获取文件名
String fileName = file.getOriginalFilename();
//选择上传的文件存放到项目的路径
String path = session.getServletContext().getRealPath(separator+"res"+separator+"upload");
if(!checkPathName(fileName,response)) return ;
String msg = baseExcelService.loadExcel(getSheet(file, path, fileName));
sendMsg(true,msg,response);
} @RequestMapping("/DownLoadExcel")
public void UpdownExcel(Students student,HttpServletResponse res,HttpSession session,HttpServletResponse response)
throws Exception{
List<Students> stus = baseExcelService.queryList(student);
if(stus.size()==0){
res.sendRedirect("/index.jsp");
return;
}
//下载的excel文件存放的本地路径
String path = session.getServletContext().getRealPath(separator+"res"+separator+"exportExcel"+separator);
ServletOutputStream os = res.getOutputStream();
Students t = baseExcelService.queryTotal(student); //标题文字，数值中的第一个值+当前日期为文件名称，以后的每个元素为每列的标题
String[] title={"studets04","id","名字","年龄","性别"};//标题文字
//对应实体类的属性值
String[] parameters ={"id","name","age","sex"};
String[] endContent = {"","","",""};
//调用父类的处理方法，生成excel文件
String filename = getOutputName(stus,path,title,parameters,t,endContent);
try {
res.reset();
res.setCharacterEncoding("utf8");
res.setContentType("application/vnd.ms-excel;charset=utf8");
res.setHeader("Content-Disposition", "attachment;fileName="
+new String(filename.getBytes("utf-8"),"iso-8859-1"));
os.write(FileUtils.readFileToByteArray(new File(path+separator+filename)));
sendResult(true,response);
os.flush();
} finally {
if (os != null) {
os.close();
}
}
}
}
2）、service层的处理，把StudentsMapper注入到BaseExcelService
BaseExcelService代码：
package cn.wangze.service; import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map; import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpSession; import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service; import cn.wangze.domain.Students;
import cn.wangze.mapper.StudentsMapper; @Service
public class BaseExcelService {
@Autowired
private StudentsMapper<Students> studentsMapper;
//判断字符串是否为空
public boolean isEmpty(String str) {
return str == null || str.length() == 0;
}
//获取单个表格(字段)存放的信息
private String getValue(Cell cell,String cellLable,Map<String,String> errMap){
cell.setCellType(Cell.CELL_TYPE_STRING);
String value = cell.getStringCellValue().trim();
return value;
}
//通过这个方法将excel表的每行的数据放到info对象里面
private String addInfo(Row row,Students info){
Map<String,String> errMap = new HashMap<String,String>();
String id = getValue(row.getCell(0),"ID",errMap);
String username = getValue(row.getCell(1),"姓名",errMap);
String age = getValue(row.getCell(2),"年龄",errMap);
String sex = getValue(row.getCell(3),"性别",errMap);
String errMsg = errMap.get("errMsg");
if(!isEmpty(errMsg)){
return errMsg;
}
info.setId(id);
info.setName(username);
info.setAge(age);
info.setSex(sex);
return null;
}
public String loadExcel(Sheet sheet) throws Exception{
//新建一个List集合，用来存放所有行信息，即每行为单条实体信息
List<Students> infos = new ArrayList<Students>();
//获取到数据行数，第一行是title，不需要存入数据库，所以rowNum从1开始
for (int rowNum = 1; rowNum <= sheet.getLastRowNum(); rowNum++) {
Students info = new Students();
String errMsg2 = addInfo(sheet.getRow(rowNum),info);
if(errMsg2 != null) return errMsg2;
infos.add(info);
}
if(infos.isEmpty()){
return "没有解析到学生数据，请查验EXCEL文件";
}
//通过studentsMapper的insertSheetData方法，将实体类存放的数据插入到数据库
int result = studentsMapper.insertSheetData(infos);
//若插入成功会返回大于1的整数，返回success
if(result >= 1){
return "success";
}
return "error";
}
//查询所有数据库存放的学生信息
public List<Students> queryList(Students students){
return studentsMapper.queryList(students);
}
//获取到的学生实体信息
public Students queryTotal(Students students){
return studentsMapper.queryTotal(students);
}
public void downExcel(HttpSession session,String separator){ }
}
3）、实体层的处理，字段要对应excel表的字段
package cn.wangze.domain;
public class Students {
String id;
String name;
String age;
String sex;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
}
4）、dao层处理：StudentsMapper.java是一个接口，业务到数据库需要执行的方法在这里声明，StudentsMapper.xml相当于接口的实现类，用来连接java和数据库的操作。
StudentsMapper.java代码：
package cn.wangze.mapper;
import java.util.List;
public interface StudentsMapper<T> {
public int insertSheetData(List<T> list);
public List<T> queryList(T t);
public T queryTotal(T t);
}
StudentsMapper.xml代码：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.wangze.mapper.StudentsMapper">
<sql id="ColumnList">
id,name,age,sex
</sql>
<sql id="ColumnList_t" >
t.id,t.name,t.age,t.sex
</sql>
<sql id="ValueList">
#{id},#{name},#{age},#{sex}
</sql>
<sql id="WhereClause">
where 1=1
<if test="id!=null and id!=''">and id=#{id}</if>
<if test="name!=null and name!=''">and name=#{name}</if>
<if test="age!=null and age!=''">and age=#{age}</if>
<if test="sex!=null and sex!=''">and sex=#{sex}</if>
</sql>
<sql id="WhereClause_pager" >
where 1=1
<if test="t.id!=null and t.id!=''">and id=#{t.id}</if>
<if test="t.name!=null and t.name!=''">and name=#{t.name}</if>
<if test="t.age!=null">and age=#{t.age}</if>
<if test="t.sex!=null and t.sex!=''">and sex=#{t.sex}</if>
</sql>
<sql id="SetClause" >
set
<trim suffixOverrides="," >
<if test="id!=null">id=#{id},</if>
<if test="name!=null">name=#{name},</if>
<if test="pid!=null">age=#{age},</if>
<if test="url!=null">sex=#{sex},</if>
</trim>
</sql>
<select id="queryList" resultType="Students">
select <include refid="ColumnList"/> from students
</select>
<select id="queryTotal" parameterType="Students" resultType="Students">
select <include refid="ColumnList" /> from students <include refid="WhereClause"/>
<!-- (select <include refid="ColumnList"/> from t_account_cash t
<include refid="WhereClauseQuery"/> group by to_char(t.add_time,'yyyy-mm-dd'),t.account_id) a -->
</select>
<insert id="insertSheetData" useGeneratedKeys="true" parameterType="java.util.List">
<!-- <selectKey resultType="long" keyProperty="id" order="AFTER">
SELECT
LAST_INSERT_ID()
</selectKey> -->
insert into students (id,name,age,sex)
values
<foreach collection="list" item="item" index="index" separator="," >
(#{item.id},#{item.name},#{item.age},#{item.sex})
</foreach>
</insert>
</mapper>
所有的代码就是这些了，操作的时候需要注意的多是路径的问题。最复杂的就是BaseExcelController的操作，它做的事情就是解析上传和创建下载excel文件。
执行完之后的结果图是这样：
在数据库查看上传的excel表：
下载到D:\tomcat\tomcat6.0.32\webapps\ExcelHandleDemo\res\exportExcel文件夹下的excel表：
这里有一点不足的地方，我相信你已经发现了，就是下载完excel表格之后，前端还没有和业务对接上，没有相应的提示来告诉操作人执行结果，只能通过代码设置好的路径去查看文件夹下是否有下载的excel文件，
不过这都是细节问题，相信难不倒聪明的各位。
这些代码是从项目里面摘出来的，所以有些可以优化的地方，视个人业务情况而定。