SpringMvc3+extjs4实现上传与下载功能

最近生活过的很充实，人一直在不停的忙碌着学习新东西。这是我最近遇到的问题，我找度娘n了很久，终于找到了解决方案！

前台代码:

<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>

后台代码：

/**
*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();
  }

}

springMvc.xml（此文件名可能跟项目的实际情况有区别）中的配置:

<!-- 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"/>

以上的就是上传文件了。

那下载呢？

下载比较简单,代码如下：

@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); 

  }

在界面上只要有一个连接地址：如:window.location.href="根路径/fileUploadDown/downfile/downLoadName=" rel="external nofollow" +name;这样就可以下载了....   超连接的写法基本一样,这里就不多说了。

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