Spring MVC文件上传下载（转载）

原文地址：

http://www.cnblogs.com/WJ-163/p/6269409.html 上传参考

http://www.cnblogs.com/lonecloud/p/5990060.html 下载参考

一、关键步骤

①引入核心JAR文件

SpringMVC实现文件上传，需要再添加两个jar包。一个是文件上传的jar包，一个是其所依赖的IO包。这两个jar包，均在Spring支持库的org.apache.commons中。

②书写控制器方法

applicationContext.xml：

注：必须创建MultipartFile实例。要不出现500错误

index.jsp页面：需指定 enctype="multipart/form-data

实现效果：　　

二、没有选择要上传的文件&&限制文件上传类型

如果没有选择要上传的文件，可以通过如下判断代码回到错误页，并配置异常类

三、多文件上传　

实现效果：

四、文件下载

实现效果：

下载不采用这种方式，参考下面这段代码：

1. /**
2.      * 文件下载
3.      * @Description:
4.      * @param fileName
5.      * @param request
6.      * @param response
7.      * @return
8.      */
9.     @RequestMapping("/download")
10.     public String downloadFile(@RequestParam("fileName") String fileName,
11.             HttpServletRequest request, HttpServletResponse response) {
12.         if (fileName != null) {
13.             String realPath = request.getServletContext().getRealPath(
14.                     "WEB-INF/File/");
15.             File file = new File(realPath, fileName);
16.             if (file.exists()) {
17.                 response.setContentType("application/force-download");// 设置强制下载不打开
18.                 response.addHeader("Content-Disposition",
19.                         "attachment;fileName=" + fileName);// 设置文件名
20.                 byte[] buffer = new byte[1024];
21.                 FileInputStream fis = null;
22.                 BufferedInputStream bis = null;
23.                 try {
24.                     fis = new FileInputStream(file);
25.                     bis = new BufferedInputStream(fis);
26.                     OutputStream os = response.getOutputStream();
27.                     int i = bis.read(buffer);
28.                     while (i != -1) {
29.                         os.write(buffer, 0, i);
30.                         i = bis.read(buffer);
31.                     }
32.                 } catch (Exception e) {
33.                     // TODO: handle exception
34.                     e.printStackTrace();
35.                 } finally {
36.                     if (bis != null) {
37.                         try {
38.                             bis.close();
39.                         } catch (IOException e) {
40.                             // TODO Auto-generated catch block
41.                             e.printStackTrace();
42.                         }
43.                     }
44.                     if (fis != null) {
45.                         try {
46.                             fis.close();
47.                         } catch (IOException e) {
48.                             // TODO Auto-generated catch block
49.                             e.printStackTrace();
50.                         }
51.                     }
52.                 }
53.             }
54.         }
55.         return null;
56.     }