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
    } 
}