使用 ajaxFileUpload 进行图片上传

前端部分

使用ajaxFileUpload 主要是为了异步上传文件，不需要开启新的页面进行上传！
由于segmentfault不能上传文件，该文件ajaxFileUpload.js的代码在本篇文章的最底部：
由于ajaxFileUpload这个文件已经很久没用更新了，所以增加了handleError: function( s,xhr,status,e )来处理错误，

前端代码如下：
第一个input中的accept属性是为了限制上传的文件属性，其他文件可以去掉该属性

引用两个js文件

<script src="jquery-1.7.1.js" type="text/javascript"></script>
 <script src="ajaxfileupload.js" type="text/javascript"></script>

上传按钮：

<input  type="file" id="upload" name="imagefile" accept="image/png,image/gif"  />
<input  type="button"  value="上传" onclick="return ajaxFileUpload();"/>

js代码：

//图片上传
    function ajaxFileUpload()
    {
         
        $.ajaxFileUpload({
                url:'/ai/app/uploadImage',//用于文件上传的服务器端请求地址
                secureuri:false,//一般设置为false
                fileElementId:'upload',//文件上传控件的id属性  <input type="file" id="upload" name="upload" />
                dataType: 'text',//返回值类型 一般设置为json
                success: function (message)  //服务器成功响应处理函数
                {
                    layer.alert(message);
                    $("#tool_icon").val(message);
                },error: function (data,e)//服务器响应失败处理函数
                {
                    alert(e);
                }
            });
        return false;
    }

后端部分

该项目使用的spring框架，需要配置bean，来接受上传的文件

<!-- 上传文件拦截，设置最大上传文件大小   10M=10*1024*1024(B)=10485760 bytes -->  
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">  
        <property name="maxUploadSize" value="10485760" />  
    </bean>

后端代码

@ResponseBody
    @RequestMapping(value="/uploadImage",method=RequestMethod.POST)
    public String uploadImage(HttpServletRequest request,@RequestParam("imagefile") multipartfile file) throws IOException{
       String getoriginalFilename = null;
       logger.debug("文件原名: " + getoriginalFilename);
       logger.debug("文件名称: " + file.getName());
       logger.debug("文件长度: " + file.getSize());
       logger.debug("文件类型: " + file.getContentType());
       if( file.isEmpty()){
          logger.error("upload image--------------------------------->Failed");
          return "please select a image";
       }
       /**文件在服务器中的实际路径*/
      
       String realPath = request.getSession().getServletContext().getRealPath("/upload");  
       logger.debug("realPath---------------------------------------->"+realPath);
       logger.debug("getoriginalFilename----------------------------->"+file.getoriginalFilename());
       
       /**写入地址中*/
       FileUtils.copyInputStreamToFile(file.getInputStream(),new File(realPath,file.getoriginalFilename()));
       
       /**使用原生方法*/
       /* byte[] bytes = file.getBytes();
       bufferedoutputstream stream = new bufferedoutputstream(new FileOutputStream(new File("/ai/images/icons/toollogo/demo.png")));
       stream.write(bytes);
       stream.close();*/
       /**返回文件在服务器中的地址，用于存储入库*/
       
       String resultUrl = "/ai/upload/"+file.getoriginalFilename();
       logger.debug("upload image file result----------------------->"+resultUrl);
       return resultUrl;
    }

相关jar包下载：org.apache.commons.io_1.3.2.jar org.apache.commons.fileupload.jar
相关jar包的地址
参考blog：
jQuery插件之ajaxFileUpload
http://blessht.iteye.com/blog/1405057
http://www.jb51.cc/article/p-qinjddkc-baw.html
http://www.cnblogs.com/rollenholt/p/3693087.html

ajaxFileUpload.js 源代码

// JavaScript Document
jQuery.extend({

    createUploadIframe: function(id,uri)
 {
   //create frame
            var frameId = 'jUploadFrame' + id;
            
            if(window.ActiveXObject) {
                var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');
                if(typeof uri== 'boolean'){
                    io.src = 'javascript:false';
                }
                else if(typeof uri== 'string'){
                    io.src = uri;
                }
            }
            else {
                var io = document.createElement('iframe');
                io.id = frameId;
                io.name = frameId;
            }
            io.style.position = 'absolute';
            io.style.top = '-1000px';
            io.style.left = '-1000px';

            document.body.appendChild(io);

            return io;   
    },createUploadForm: function(id,fileElementId)
 {
  //create form 
  var formId = 'jUploadForm' + id;
  var fileId = 'jUploadFile' + id;
  var form = jQuery('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>'); 
  var oldElement = jQuery('#' + fileElementId);
  var newElement = jQuery(oldElement).clone();
  jQuery(oldElement).attr('id',fileId);
  jQuery(oldElement).before(newElement);
  jQuery(oldElement).appendTo(form);
  //set attributes
  jQuery(form).css('position','absolute');
  jQuery(form).css('top','-1200px');
  jQuery(form).css('left','-1200px');
  jQuery(form).appendTo('body');  
  return form;
    },ajaxFileUpload: function(s) {
        // Todo introduce global settings,allowing the client to modify them for all requests,not only timeout  
        s = jQuery.extend({},jQuery.ajaxSettings,s);
        var id = s.fileElementId;        
  var form = jQuery.createUploadForm(id,s.fileElementId);
  var io = jQuery.createUploadIframe(id,s.secureuri);
  var frameId = 'jUploadFrame' + id;
  var formId = 'jUploadForm' + id;  
        
        if( s.global && ! jQuery.active++ )
  {
   // Watch for a new set of requests
   jQuery.event.trigger( "ajaxStart" );
  }            
        var requestDone = false;
        // Create the request object
        var xml = {};   
        if( s.global )
        {
         jQuery.event.trigger("ajaxSend",[xml,s]);
        }            
        
        var uploadCallback = function(isTimeout)
  {  
   // Wait for a response to come back 
   var io = document.getElementById(frameId);
            try 
   {    
    if(io.contentwindow)
    {
      xml.responseText = io.contentwindow.document.body?io.contentwindow.document.body.innerHTML:null;
                  xml.responseXML = io.contentwindow.document.XMLDocument?io.contentwindow.document.XMLDocument:io.contentwindow.document;
      
    }else if(io.contentDocument)
    {
      xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;
                 xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;
    }      
            }catch(e)
   {
    jQuery.handleError(s,xml,null,e);
   }
            if( xml || isTimeout == "timeout") 
   {    
                requestDone = true;
                var status;
                try {
                    status = isTimeout != "timeout" ? "success" : "error";
                    // Make sure that the request was successful or notmodified
                    if( status != "error" )
     {
                        // process the data (runs the xml through httpData regardless of callback)
                        var data = jQuery.uploadHttpData( xml,s.dataType );                        
                        if( s.success )
                        {
       // ifa local callback was specified,fire it and pass it the data
                         s.success( data,status );
                        };                 
                        if( s.global )
                        {
       // Fire the global callback
                         jQuery.event.trigger( "ajaxSuccess",s] );
                        };                            
                    } else
                    {
                     jQuery.handleError(s,status);
                    }
                        
                } catch(e) 
    {
                    status = "error";
                    jQuery.handleError(s,e);
                };                
                if( s.global )
                {
     // The request was completed
                 jQuery.event.trigger( "ajaxComplete",s] );
                };
                    

                // Handle the global AJAX counter
                if(s.global && ! --jQuery.active)
                {
                 jQuery.event.trigger("ajaxStop");
                };
                if(s.complete)
                {
                  s.complete(xml,status);
                } ;                 

                jQuery(io).unbind();

                setTimeout(function()
         { try 
          {
           jQuery(io).remove();
           jQuery(form).remove(); 
           
          } catch(e) 
          {
           jQuery.handleError(s,e);
          }         

         },100);

                xml = null;

            };
        }
        // Timeout checker
        if( s.timeout > 0 ) 
  {
            setTimeout(function(){
                
                if( !requestDone )
                {
     // Check to see ifthe request is still happening
                 uploadCallback( "timeout" );
                }
                
            },s.timeout);
        }
        try 
  {
   var form = jQuery('#' + formId);
   jQuery(form).attr('action',s.url);
   jQuery(form).attr('method','POST');
   jQuery(form).attr('target',frameId);
            if(form.encoding)
   {
                form.encoding = 'multipart/form-data';    
            }
            else
   {    
                form.enctype = 'multipart/form-data';
            }   
            jQuery(form).submit();

        } catch(e) 
  {   
            jQuery.handleError(s,e);
        }
        if(window.attachEvent){
            document.getElementById(frameId).attachEvent('onload',uploadCallback);
        }
        else{
            document.getElementById(frameId).addEventListener('load',uploadCallback,false);
        }   
        return {abort: function () {}}; 

    },uploadHttpData: function( r,type ) {
        var data = !type;
        data = type == "xml" || data ? r.responseXML : r.responseText;
        // ifthe type is "script",eval it in global context
        if( type == "script" )
        {
         jQuery.globalEval( data );
        }
            
        // Get the JavaScript object,ifJSON is used.
        if( type == "json" )
        {
         eval( "data = " + data );
        }
            
        // evaluate scripts within html
        if( type == "html" )
        {
         jQuery("<div>").html(data).evalScripts();
        }
            
        return data;
    },handleError: function( s,e )      {  
        // If a local callback was specified,fire it  
                if ( s.error ) {  
                    s.error.call( s.context || s,e );  
                }  
  
                // Fire the global callback  
                if ( s.global ) {  
                    (s.context ? jQuery(s.context) : jQuery.event).trigger( "ajaxError",[xhr,s,e] );  
                }  
    }  
});