SpringMvc3+extjs4实现上传与下载功能

<script>   Ext.onReady(function() {    Ext.create('Ext.form.Panel', {      title : '文件上传',      width : 400,      bodyPadding : 10,      frame : true,      renderTo : document.body,      items : [ {        xtype : 'filefield',        name : '文件',        fieldLabel : 'File',        labelWidth : 50,        msgTarget : 'side',        allowBlank : false,        anchor : '100%',        buttonText : '请选择文件...'      } ],      buttons : [ {        text : '上传',        handler : function() {          var form = this.up('form').getForm();          if (form.isValid()) {            form.submit({              url : '根路径/fileUploadDown/fileUpload',              waitMsg : '正在上传文件中...',              success : function(fp, o) {                Ext.Msg.alert('上传文件成功!');              }            });          }        }      } ]    });  });</script>

/***记录返回结果*/ class ExtJSFormResult {  private boolean success;  public boolean isSuccess() {    return success;  }  public void setSuccess(boolean success) {  }  public String toString() {    return "{success:" + this.success + "}";  }} class FileUploadBean {    private CommonsMultipartFile file;    public CommonsMultipartFile getFile() {      return file;    }    public void setFile(CommonsMultipartFile file) {      this.file = file;    }}/** * 文件的上传与下载 * @author Administrator * */@Controller@RequestMapping(value = "/fileUploadDown")public class FileUploadAndDownController {    private static int countter=1; //定义一个计数器,用于上传文件的重命名    @Autowired  private ProAnnexDao<ProAnnex> proAnnextDao;      public void setProAnnextDao(ProAnnexDao<ProAnnex> proAnnextDao) {    this.proAnnextDao = proAnnextDao;  }  @RequestMapping(value="fileUpload",method = RequestMethod.POST)  public @ResponseBody String create(RedirectAttributes redirectAttributes,FileUploadBean uploadItem,       BindingResult result,HttpSession session){    //获取根路径    String uploadFolderPath = session.getServletContext().getRealPath("/");     ExtJSFormResult extjsFormResult = new ExtJSFormResult();    try {            if (result.hasErrors()) {        for (ObjectError error : result.getAllErrors()) {          System.err.println("Error: " + error.getCode() + " - "              + error.getDefaultMessage());        }        // 设置ExtJS返回 - error        extjsFormResult.setSuccess(false);        return extjsFormResult.toString();      }      MultipartFile file = uploadItem.getFile();      String fileName = null;      InputStream inputStream = null;      OutputStream outputStream = null;      if(file.getSize()>0){         System.out.println("File Size:::" + file.getSize());        if(file.getSize()>5242880){           System.out.println("File Size:::" + file.getSize());           extjsFormResult.setSuccess(false);          return "error";        }               inputStream = file.getInputStream();           File newFile = new File(uploadFolderPath + "fileUpload/");       //如果文件路径不存在就新建一个       if(!newFile.exists()){         newFile.mkdirs();       }       //获取文件名       String name=file.getOriginalFilename();       //从数据库中查询存在此类文件名否        Long count=proAnnextDao.isRepeatName(name);        //如果存在一样的文件名,就进行从命名        if (count>0) {          name=name.substring(0, name.lastIndexOf("."))+"("+(countter++)+")"+name.substring(name.lastIndexOf("."));        }                fileName = uploadFolderPath + "fileUpload/" + name;        outputStream = new FileOutputStream(fileName);         int readBytes = 0;        byte[] buffer = new byte[10000];        while ((readBytes = inputStream.read(buffer, 0, 10000)) != -1) {            outputStream.write(buffer, 0, readBytes);        }                outputStream.close();        inputStream.close();                     }      // 设置ExtJS返回 - sucsess      extjsFormResult.setSuccess(true);    } catch (Exception e) {            e.printStackTrace();      // 设置ExtJS返回 - error          extjsFormResult.setSuccess(false);    }        return extjsFormResult.toString();  }  }

<!-- 上传文件,限制大小的配置 -->   <bean id="multipartResolver"    class="org.springframework.web.multipart.commons.CommonsMultipartResolver">     <!--resolveLazily属性启用是为了推迟文件解析，以便在Upload中捕获文件大小异常-->    <property name="resolveLazily" value="true"/>    <property name="maxUploadSize" value="5242880" />  </bean>      <!-- 将无法mapping到Controller的path交给default servlet handler处理   -->    <mvc:default-servlet-handler/><!-- 使用默认的servlet来响应静态文件 -->  <!-- 文件的上传与下载 -->  <mvc:view-controller path="/" view-name="redirect:/fileUploadDown"/>

@RequestMapping("/downloadFile")   public void download(@Valid @ModelAttribute("downLoadName") String downLoadName,      HttpServletResponse response,HttpSession session,BindingResult result,HttpServletRequest request) throws IOException {         response.setCharacterEncoding("UTF-8");    request.setCharacterEncoding("UTF-8");    //获取文件的路径    String url=session.getServletContext().getRealPath("/")+"/fileUpload/"+downLoadName;    System.out.println(url);    File file=new File(url);        InputStream input = FileUtils.openInputStream(file);     byte[] data = IOUtils.toByteArray(input);      //System.out.println("文件名:"+downLoadName);    response.reset();    //设置响应的报头信息(中文问题解决办法)    response.setHeader("content-disposition","attachment;fileName="+URLEncoder.encode(downLoadName, "UTF-8"));    response.addHeader("Content-Length", "" + data.length);     response.setContentType("application/octet-stream; charset=UTF-8");         IOUtils.write(data, response.getOutputStream());     IOUtils.closeQuietly(input);       }