spring mvc注解文件上传下载

需要两个包：

包如何导入就不介绍了，前端代码如下（一定要加enctype="multipart/form-data"让服务器知道是文件上传）：

<form action="upload.do" method="post" enctype="multipart/form-data">
<input type="file" id="upimage" name="file" onchange="setImagePreview()"/> <input type="submit" value="Submit" /></form>

java代码：

 import org.apache.commons.io.FileUtils;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.multipart.MultipartFile;
 import org.springframework.ui.Model;
 /**
  * {@Controller} spring注解，指定此类为controller
  * {@RequestMapping} 路径
  * @author v_zweiwang
  *
  */
 @Controller
 @RequestMapping("/image")
 public class ImageController {
     @RequestMapping("/toupload")//用于跳转到上传页面
     public String toUpload(){
         return "/WEB-INF/html/upload.html";
     }

     @RequestMapping("/upload")
     public String upload(@RequestParam(value = "file", required = false) MultipartFile file,HttpServletRequest request) {
         SimpleDateFormat dateformat = new SimpleDateFormat("yyyy_MM_dd_HH_mm_ss_SS"); //格式化时间
         /**构建图片保存的目录**/
         String upTime =dateformat.format(new Date()); //用于区别保存
         String path=request.getSession().getServletContext().getRealPath("/");//获取项目在服务器的绝对路径file C:....webApp/ =url http://...webApp/ 不明白就打印path
         String fileName = file.getOriginalFilename(); //获得文件名
         String filePath="/upload/"+upTime+"/";//文件相对路径
         File targetFile = new File(path+filePath,fileName); //新建一个文件
         if(!targetFile.exists()){
             targetFile.mkdirs();
         }  

         //保存
         try {
             file.transferTo(targetFile);
         } catch (Exception e) {
             e.printStackTrace();
         }
         System.out.println(request.getContextPath()+filePath+fileName);
         return "redirect:/image/download.do?filepath="+filePath+fileName;//直接重定向下载图片
     }

     @RequestMapping("download")
     public ResponseEntity<byte[]> download(HttpServletRequest request,String filepath) throws IOException {
         String path=request.getSession().getServletContext().getRealPath("/")+filepath;//获取图片路径 filepath为图片相对路径
         System.out.println(path);
             File file=new File(path);
             HttpHeaders headers = new HttpHeaders();
             String fileName=new String("filescan.png".getBytes("UTF-8"),"iso-8859-1");//为了解决中文名称乱码问题
             headers.setContentDispositionFormData("attachment", fileName); //下载后显示的名字
             headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
             return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),
                                               headers, HttpStatus.CREATED);  //向浏览器发送数据
     }
 }