SpringMVC笔记（五）文件的上传下载

一、SpringMVC实现文件的上传

Spring MVC 上下文中默认没有为文件上传提供了直接的支持，因 此默认情况下不能处理文件的上传工作，

如果想使用 Spring 的文件上传功能，需现在上下文中配置 CommonsMultipartResovler:

二、文件上传的步骤：
    1.加入jar包：
        commons-fileupload-1.3.1.jar
        commons-io-2.4.jar

   2.在SpringMVC配置文件中配置CommonsMultipartResovler

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<!-- 配置文件上传 -->     <bean  id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">        <property name="defaultEncoding" value="utf-8"></property>        <property name="maxUploadSize" value="1024000"></property>     </bean>

   3.前端表单：注意：需要请求方式：POST，input类型：file，(官网：www.fhadmin.org)属性：enctype="multipart/form-data"

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<form action="${pageContext.request.contextPath }/testUpload" method="post" enctype="multipart/form-data">     file:<input type="file" name="photo">     desc:<input type="text" name="desc">     <input type="submit" value="上传">  </form>

    4.文件上传方法的实现

    

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@RequestMapping("/testUpload") public String testUpload(HttpServletRequest request,@RequestParam(value="desc",required=false)String desc,@RequestParam("photo") CommonsMultipartFile file){     ServletContext servletContext = request.getServletContext();     String realPath = servletContext.getRealPath("/upload");     File file1 = new File(realPath);     if(!file1.exists()){         file1.mkdir();     }     OutputStream out = null;     InputStream in = null;     //uuid_name.jpg     String prefix = UUID.randomUUID().toString();     prefix = prefix.replace("-","");     String fileName = prefix+"_"+file.getOriginalFilename();     System.out.println(fileName);     try {         out = new FileOutputStream(new File(realPath+"\\"+fileName));         in = file.getInputStream();         //创建一个缓冲区(官网：www.fhadmin.org)         byte buffer[]=new byte[1024];         //判断输入流中的数据是否已经对完         int len=0;         //循环将输入流读入到缓冲区中（len=in.read(buffer)>0）表示in里面还有数据         while((len=in.read(buffer))!=-1){             //使用FileOutPutStream输出流，将缓冲区的数据输出到指定目录文件             out.write(buffer,0,len);            }     } catch (Exception   e) {         e.printStackTrace();     }     //关闭输入流、输出流(官网：www.fhadmin.org)     try {         out.close();         in.close();     } catch (IOException e) {         // TODO Auto-generated catch block         e.printStackTrace();     }     return  "success"; }

 三、文件的下载

        文件能上传就能下载

      1.用ResponseEntity<byte[]> 返回值完成文件下载：

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@RequestMapping(value="/testDownLoad")     public ResponseEntity<byte[]> testDonwLoad(HttpServletRequest request) throws Exception{         ServletContext servletContext=request.getServletContext();         String fileName="风吹麦浪.mp3";         String realPath = servletContext.getRealPath("/WEB-INF/"+fileName);         InputStream in=new FileInputStream(new File(realPath));         byte [] body=new byte[in.available()];         in.read(body);         MultiValueMap<String, String> headers=new HttpHeaders();         fileName=new String(fileName.getBytes("gbk"),"iso8859-1");         headers.set("Content-Disposition", "attachment;filename="+fileName);         HttpStatus status=HttpStatus.OK;         ResponseEntity<byte []> responseEntity=new ResponseEntity<>(body, headers,status);         in.close();         return responseEntity;      }