jquery如何实现异步文件上传ajaxfileupload.js

$.ajaxFileUpload({ 
 url:'',//后台接口地址 
 type: "post", 
 secureuri: false, //一般设置为false 
 fileElementId: 'ofx', // 上传文件的id、name属性名 
 dataType: 'json', 
 success: function(data, status){ 
  
 }, 
 error: function(data, status, e){ 
 } 
 }); 

jQuery.extend({
 createUploadIframe: function(id, uri)
 {
  
 //create frame
 var frameId = 'jUploadFrame' + id;
 var iframeHtml = '<iframe id="' + frameId + '" name="' + frameId + '" ';
 if(window.ActiveXObject)
 {
 if(typeof uri== 'boolean'){
 iframeHtml += ' src="' + 'javascript:false' + '"';

 }
 else if(typeof uri== 'string'){
 iframeHtml += ' src="' + uri + '"';

 } 
 }
 iframeHtml += ' />';
 jQuery(iframeHtml).appendTo(document.body);

 return jQuery('#' + frameId).get(0); 
 },
 createUploadForm: function(id,fileElementId,data,fileElement)
 {
 //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>'); 
 if(data)
 {
 for(var i in data)
 {
 jQuery('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').appendTo(form);
 } 
 }

 
 if(typeof(fileElementId) == 'string'){
 fileElementId = [fileElementId];
 }
 for(var i in fileElementId){
 var oldElement = jQuery('#' + fileElementId[i]);
 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 = new Date().getTime()  
 var form = jQuery.createUploadForm(id, s.fileElementId, (typeof(s.data)=='undefined'&#63;false:s.data),s.fileElement);
 var io = jQuery.createUploadIframe(id, s.secureuri);
 var frameId = 'jUploadFrame' + id;
 var formId = 'jUploadForm' + id; 
  // Watch for a new set of requests
  if ( s.global && ! jQuery.active++ )
 {
 jQuery.event.trigger( "ajaxStart" );
 }   
  var requestDone = false;
  // Create the request object
  var xml = {} 
  if ( s.global )
   jQuery.event.trigger("ajaxSend", [xml, s]);
  // Wait for a response to come back
  var uploadCallback = function(isTimeout)
 { 
 var io = document.getElementById(frameId);
   try 
 { 
 if(io.contentWindow)
 {
  xml.responseText = io.contentWindow.document.body&#63;io.contentWindow.document.body.innerHTML:null;
     xml.responseXML = io.contentWindow.document.XMLDocument&#63;io.contentWindow.document.XMLDocument:io.contentWindow.document;
  
 }else if(io.contentDocument)
 {
  xml.responseText = io.contentDocument.document.body&#63;io.contentDocument.document.body.innerHTML:null;
     xml.responseXML = io.contentDocument.document.XMLDocument&#63;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" &#63; "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 a local callback was specified, fire it and pass it the data
      if ( s.success )
       s.success( data, status );
 
      // Fire the global callback
      if( s.global )
       jQuery.event.trigger( "ajaxSuccess", [xml, s] );
     } else
      jQuery.handleError(s, xml, status);
    } catch(e) 
 {
     status = "error";
     jQuery.handleError(s, xml, status, e);
    }

    // The request was completed
    if( s.global )
     jQuery.event.trigger( "ajaxComplete", [xml, s] );

    // Handle the global AJAX counter
    if ( s.global && ! --jQuery.active )
     jQuery.event.trigger( "ajaxStop" );

    // Process result
    if ( s.complete )
     s.complete(xml, status);

    jQuery(io).unbind()

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

   }, 100)

    xml = null

   }
  }
  // Timeout checker
  if ( s.timeout > 0 ) 
 {
   setTimeout(function(){
    // Check to see if the request is still happening
    if( !requestDone ) 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)
 {
 jQuery(form).attr('encoding', 'multipart/form-data');   
   }
   else
 { 
 jQuery(form).attr('enctype', 'multipart/form-data'); 
   } 
   jQuery(form).submit();

  } catch(e) 
 { 
   jQuery.handleError(s, xml, null, e);
  }
 
 jQuery('#' + frameId).load(uploadCallback);
  return {abort: function(){
 try
 {
 jQuery('#' + frameId).remove();
 jQuery(form).remove();
 }
 catch(e){}
 }};
 },

 uploadHttpData: function( r, type ) {
  var data = !type;
  data = type == "xml" || data &#63; r.responseXML : r.responseText;
 
  // If the type is "script", eval it in global context
  if ( type == "script" )
   jQuery.globalEval( data );
  // Get the JavaScript object, if JSON is used.
  if ( type == "json" ){
 以下为新增代码///
   data = r.responseText;
   var start = data.indexOf(">");
   if(start != -1) {
  var end = data.indexOf("<", start + 1);
  if(end != -1) {
  data = data.substring(start + 1, end);
  }
 }
 }
   ///以上为新增代码///
   eval( "data = " + data );
  // evaluate scripts within html
  if ( type == "html" )
   jQuery("<div>").html(data).evalScripts();

  return data;
 },
 
 handleError: function( s, xml, status, e ) {
 // If a local callback was specified, fire it
 if ( s.error )
 s.error( xml, status, e );

 // Fire the global callback
 if ( s.global )
 jQuery.event.trigger( "ajaxError", [xml, s, e] );
 }
});