Spring MVC 上传文件

Spring MVC上传文件需要如下步骤：

　　1、前台页面，form属性 method设置为post,enctype="multipart/form-data"  input的type类型设置为file。

　  <h>添加用户</h>
    <form name="userForm" action="/file/upload2" method="post" enctype="multipart/form-data" >
        选择文件：<input type="file" name="file">
        
        <input type="submit" value="上传" >
    </form>

　　2、引入jar包commons-fileupload.jar以及commons-io.jar包

　　3、在spring配置文件bean 注入MultipartResolver处理器

　　<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
          <property name="defaultEncoding" value="utf-8" />
          <property name="maxUploadSize" value="10485760000" />
          <property name="maxInMemorySize" value="40960" />
　　</bean>

　　4.1、controller里面方法的参数处使用@RequestParam("file") CommonsMultipartFile file,指定传过来的file是CommonsMultipartFile类型
　　　  然后即可使用IO读写文件。

    @RequestMapping("/upload")
    public String addUser(@RequestParam("file") CommonsMultipartFile file,HttpServletRequest request) throws IOException{
        System.out.println("fileName---->" + file.getOriginalFilename());
        
        if(!file.isEmpty()){
            try {
                FileOutputStream os = new FileOutputStream("D:/" + new Date().getTime() + file.getOriginalFilename());
                InputStream in = file.getInputStream();
                int b = 0;
                while((b=in.read()) != -1){
                    os.write(b);
                }
                os.flush();
                os.close();
                in.close();
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return "/success";
    }

　　4.2、或者在controller直接使用spring自带的封装了的文件上传类org.springframework.web.multipart.commons.CommonsMultipartFile以及
　　　　  org.springframework.web.multipart.commons.CommonsMultipartResolver

    @RequestMapping("/upload2")
    public String upload2(HttpServletRequest request,HttpServletResponse response) throws IllegalStateException, IOException{
        //
        CommonsMultipartResolver multipartResolver  = new CommonsMultipartResolver(request.getSession().getServletContext());
        if(multipartResolver.isMultipart(request)){
            //需要有表单域name属性，否则将取不到对应的file
            MultipartHttpServletRequest  multiRequest = (MultipartHttpServletRequest)request;
            
            Iterator<String>  iter = multiRequest.getFileNames();
            while(iter.hasNext()){
                    MultipartFile file = multiRequest.getFile((String)iter.next());
                if(file != null){
                    String fileName = "demoUpload" + file.getOriginalFilename();
                    String path = "D:/" + fileName;
                    
                    File localFile = new File(path);
                    
                    file.transferTo(localFile);
                }     
            }
        }
        return "/success";
    }