文件上传步骤

第一步：由于SpringMVC使用的是commons-fileupload实现，故将其组件引入项目中,这里用到的是commons-fileupload-1.2.1.jar和commons-io-1.3.2.jar。

第二步：spring-mvx中配置MultipartResolver处理器。可在此加入对上传文件的属性限制。

第三步：在Controller的方法中添加MultipartFile参数。该参数用于接收表单中file组件的内容

第四步：编写前台表单。注意enctype="multipart/form-data"以及<input type="file" name="****"/>,如果是单个文件直接使用MultipartFile 即可

springmvc.xml

<!-- 文件上传 -->
 <bean id="multipartResolver"  
   class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
   <!-- 设置上传文件的最大尺寸为10MB -->  
   <property name="maxUploadSize">  
       <value>10000000</value>  
   </property>  
  </bean>  

controller

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

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

import org.apache.commons.fileupload.FileUpload;
import org.apache.commons.io.FileUtils;
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;

@Controller
public class FileUploadController {


    //TODO:上传代码
    @RequestMapping("/fileupload")
    public ModelAndView upload(String name,
            //上传多个文件
            @RequestParam("file") MultipartFile[] file,
            HttpServletRequest request) throws IllegalStateException,
            IOException {

        //获取文件 存储位置
        String realPath = request.getSession().getServletContext()
                .getRealPath("/uploadFile");

        File pathFile = new File(realPath);

        if (!pathFile.exists()) {
            //文件夹不存 创建文件
            pathFile.mkdirs();
        }
        for (MultipartFile f : file) {

            System.out.println("文件类型："+f.getContentType());
            System.out.println("文件名称："+f.getOriginalFilename());
            System.out.println("文件大小:"+f.getSize());
            System.out.println(".................................................");
            //将文件copy上传到服务器
            f.transferTo(new File(realPath + "/" + f.getOriginalFilename()));
             //FileUtils.copy
        }
        //获取modelandview对象
        ModelAndView view = new ModelAndView();
        view.setViewName("redirect:index.jsp");
        return view;
    }



    //TODO:下载代码
    @RequestMapping(value = "/filedownload")  
    public ModelAndView download(HttpServletRequest request,  
            HttpServletResponse response) throws Exception {  

//        String storeName = "Spring3.xAPI_zh.chm";  
        String storeName="文件.txt";
        String contentType = "application/octet-stream";  
        FileUploadController.download(request, response, storeName, contentType);  
        return null;  
    }  

    //文件下载 主要方法
    public static void download(HttpServletRequest request,  
            HttpServletResponse response, String storeName, String contentType
           ) throws Exception {  

        request.setCharacterEncoding("UTF-8");  
        BufferedInputStream bis = null;  
        BufferedOutputStream bos = null;  

        //获取项目根目录
        String ctxPath = request.getSession().getServletContext()  
                .getRealPath("");  

        //获取下载文件露肩
        String downLoadPath = ctxPath+"/uploadFile/"+ storeName;  

        //获取文件的长度
        long fileLength = new File(downLoadPath).length();  

        //设置文件输出类型
        response.setContentType("application/octet-stream");  
        response.setHeader("Content-disposition", "attachment; filename="  
                + new String(storeName.getBytes("utf-8"), "ISO8859-1")); 
        //设置输出长度
        response.setHeader("Content-Length", String.valueOf(fileLength));  
        //获取输入流
        bis = new BufferedInputStream(new FileInputStream(downLoadPath));  
        //输出流
        bos = new BufferedOutputStream(response.getOutputStream());  
        byte[] buff = new byte[2048];  
        int bytesRead;  
        while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {  
            bos.write(buff, 0, bytesRead);  
        }  
        //关闭流
        bis.close();  
        bos.close();  
    }  

}  

注意：注意：设置表单中form表单的属性为：enctype="multipart/form-data"