在實際應用中，經常會遇到上傳Excel或者下載Excel的情況，比如匯入資料、下載統計資料等等場景。針對這個問題，我寫了個基於SpringMVC的簡單上傳下載示例，其中Excel的處理使用Apache的POI元件。

主要依賴的包如下： 

<dependency>
			<groupId>commons-io</groupId>
			<artifactId>commons-io</artifactId>
			<version>2.4</version>
		</dependency>
		<dependency>
			<groupId>commons-fileupload</groupId>
			<artifactId>commons-fileupload</artifactId>
			<version>1.3.1</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-web</artifactId>
			<version>4.0.0.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>4.0.0.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.apache.poi</groupId>
			<artifactId>poi</artifactId>
			<version>3.10.1</version>
		</dependency>

相關處理類：

（一）Controller類 

package com.research.spring.controller;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;

import com.research.spring.model.UserInfo;
import com.research.spring.view.ExcelView;

@Controller
@RequestMapping("/file")
public class FileController {

	/**
	 * Excel檔案上傳處理
	 * @param file
	 * @return
	 */
	@RequestMapping("/upload")
	public ModelAndView uploadExcel(@RequestParam("file") MultipartFile file){
		List<UserInfo> list = new ArrayList<UserInfo>();
                //這裡只處理檔名包括“使用者”的檔案，模板使用下載模板
		if( file.getOriginalFilename().contains("使用者") ){
			try {
				Workbook wb = new HSSFWorkbook(file.getInputStream());
				Sheet sheet = wb.getSheetAt(0);
				for( int i = 1; i <= sheet.getLastRowNum(); i++ ){
					Row row = sheet.getRow(i);
					UserInfo info = new UserInfo();
					info.setUserName(row.getCell(0).getStringCellValue());
					info.setPassword(row.getCell(1).getStringCellValue());
					list.add(info);
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		ModelAndView mav = new ModelAndView("content");
		mav.addObject("content",list.toString());
		return mav;
	}
	
	/**
	 * Excel檔案下載處理
	 */
	@RequestMapping("/download")
	public ModelAndView downloanExcel(){
		List<UserInfo> list = new ArrayList<UserInfo>();
		UserInfo userInfo = new UserInfo();
		userInfo.setPassword("0000");
		userInfo.setUserName("sdfas");
		list.add(userInfo);
		list.add(userInfo);
		list.add(userInfo);
		list.add(userInfo);
		Map<String,List<UserInfo>> map = new HashMap<String, List<UserInfo>>();
		map.put("infoList", list);
		ExcelView ve = new ExcelView();
		return new ModelAndView(ve,map);
	}	
} 
 

 （二）實體類 

package com.research.spring.model;

public class UserInfo {

	private String userName;
	
	private String password;

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	@Override
	public String toString() {
		return "UserInfo [userName=" + userName + ", password=" + password
				+ "]";
	}	
}
 

（三）View類

這個類在下載時用到，在Spring渲染頁面時使用自定義的View類進行Excel的相關處理。 

package com.research.spring.view;

import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.springframework.web.servlet.view.document.AbstractExcelView;

import com.research.spring.model.UserInfo;

/**
 * 下載Excel檢視
 * 
 * @author wdmcygah
 *
 */  
public class ExcelView extends AbstractExcelView {

	@Override
	protected void buildExcelDocument(Map<String, Object> model,
			HSSFWorkbook workbook, HttpServletRequest request,
			HttpServletResponse response) throws Exception {
		@SuppressWarnings("unchecked")
		List<UserInfo> list = (List<UserInfo>) model.get("infoList");
		if (list != null && list.size() != 0) {
			int len = list.size();
			Sheet sheet = workbook.createSheet();
			// 第一行文字說明
			Row row = sheet.createRow(0);
			Cell cell = row.createCell(0, Cell.CELL_TYPE_STRING);
			cell.setCellValue("使用者名稱");
			cell = row.createCell(1, Cell.CELL_TYPE_STRING);
			cell.setCellValue("密碼");

			//下面是具體內容
			for (int i = 0; i < len; i++) {
				row = sheet.createRow(i + 1);
				cell = row.createCell(0, Cell.CELL_TYPE_STRING);
				cell.setCellValue(list.get(i).getUserName());
				cell = row.createCell(1, Cell.CELL_TYPE_STRING);
				cell.setCellValue(list.get(i).getPassword());
			}
		}

		response.setContentType("application/vnd.ms-excel");
		response.setCharacterEncoding("utf-8");
		//這裡對檔名進行編碼，保證下載時漢字顯示正常
		String fileName = URLEncoder.encode("使用者.xls", "utf-8");
		//Content-disposition屬性設定成以附件方式進行下載
		response.setHeader("Content-disposition", "attachment;filename="
				+ fileName);
		OutputStream os = response.getOutputStream();
		workbook.write(os);
		os.flush();
		os.close();
	}
}

（四）主要配置檔案

上傳檔案時需要在配置檔案中配置MultipartResolver類，配置後Spring會自動將檔案傳成MultipartFile物件，然後就可以進行相應的處理。示例看Controller類。 

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:util="http://www.springframework.org/schema/util"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
  http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
  http://www.springframework.org/schema/context
  http://www.springframework.org/schema/context/spring-context-3.0.xsd 
  http://www.springframework.org/schema/mvc 
  http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
  http://www.springframework.org/schema/util
  http://www.springframework.org/schema/util/spring-util-3.0.xsd">

	<context:component-scan base-package="com.research" />

	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="viewClass"	value="org.springframework.web.servlet.view.JstlView" />
		<property name="prefix" value="/WEB-INF/" />
		<property name="suffix" value=".jsp" />
	</bean>

	<!-- 上傳檔案解析器配置 -->
	<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
		<property name="defaultEncoding" value="UTF-8"></property>
		<!-- 上傳檔案的大小限制 ，單位是位元組-->
		<property name="maxUploadSize" value="5242880000000"></property>
		<!-- 上傳檔案的臨時路徑，上傳完成後會自動刪除 -->
		<property name="uploadTempDir" value="upload/temp"></property>
	</bean>
</beans>

（五）測試頁面

<html>
<head>        
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
</head>
<body>
<h3>測試下載Excel功能</h3>
<form action="file/download.htm" enctype="multipart/form-data" method="post">
	<input type="submit" value="下載Excel"></input>	
</form>

<h3>測試上傳Excel功能</h3>
<form action="file/upload.htm" enctype="multipart/form-data" method="post">
	<input type="file" name="file"></input>
	<input type="submit" value="上傳Excel"></input>	
</form>
</body>
</html>

如果想看完整原始碼，可以到我的Github倉庫檢視：https://github.com/wdmcygah/research-spring。 其中，上傳檔案只處理符合下載模板的檔案。若要處理其它檔案需要自實現。程式碼測試通過無誤。