springMvc3+extjs4的上传与下载

　　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="+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.