JFinal 은 ajax fileupload 를 사용 하여 이미지 업로드 및 미리 보 기 를 실현 합 니 다.

<script type="text/javascript" src="<%=request.getContextPath() %>/js/jquery.min.js"></script>
<script type="text/javascript" src="<%=request.getContextPath() %>/media/ajaxupload/ajaxfileupload.js"></script>

<input type="file" class="upload" name="file" id="upfile" onchange="ajaxFileUpload('upfile')"/>
<!--      --> 
<img src="<c:if test="${banner.img!=null}"><%=request.getContextPath() %>/media/file/${banner.img}</c:if>" style="width:300px;height:100px;" id="imgsrc"/>
<!--      ,           -->
<input id='imgurl' type='hidden' name="imgurl" style="height:30px;width:100%" value='${banner.img}'/>

function ajaxFileUpload(fileEid, paramdata){
 if(typeof(paramdata)=='undefined') paramdata = {};
 var $file=$('#'+fileEid).val();
 if($file=='') {alert("           ，  "); return;}

 $.ajaxFileUpload({
 url:'<%=request.getContextPath()%>/banner/uploadpic',
 secureuri:false,
 fileElementId:fileEid,
 dataType: 'text',
 data:paramdata,
 success: function (result){
  var result = result.substring(result.indexOf("{"),result.indexOf("}")+1);
  result = eval("("+result+")");

  if(result.t==1){
  $("#imgsrc").attr("src","<%=request.getContextPath() %>/media/file/"+result.msg);
  $("#imgurl").val(result.msg);
  }else{
  alert("    ");
  }
 }
 });
}

public void uploadpic(){
 UploadFile upfile = getFile();//JFinal  getFile()      
 File file = upfile.getFile();
 String filename = file.getName();
 String delfilename = filename;
 if(filename!=null && !filename.equals("")){
 filename = new SimpleDateFormat("yyyyMMddkkmmss").format(new Date())+filename;
 /**
  *       
  */
 String path = getRequest().getSession().getServletContext()
  .getRealPath("/");
 String newPath = "/media/file/";//            
 /**
  *        
  */
 File floder = new File(path + newPath);
 if (!floder.exists()) {
  floder.mkdirs();
 }
 /**
  *      
  */
 FileInputStream fis = null;
 FileOutputStream fos = null;
 try{
  File savePath = new File(path + newPath + filename);
  if(!savePath.isDirectory()) savePath.createNewFile();
  fis = new FileInputStream(file);
  fos = new FileOutputStream(savePath);
  byte[] bt = new byte[300];
  while (fis.read(bt, 0, 300) != -1) {
  fos.write(bt, 0, 300);
  }
 }catch(Exception e){
  e.printStackTrace();
 }finally{
  try{
  if(null!=fis) fis.close();
  if(null!=fos) fos.close();
  }catch(Exception e){
  e.printStackTrace();
  }
 }

 /**
  *      ，JFinal          /upload（    ）
  */
 File delFile = new File(path+"/upload/"+delfilename);
 if(delFile.exists()){
  delFile.delete();
 }
 setAttr("msg",filename);
 setAttr("t",1);
 }else{
 setAttr("t",0);
 }
 renderJson();
}

jQuery.extend({
 createUploadIframe: function(id, uri) {
 //create frame
 var frameId = 'jUploadFrame' + id;
 var iframeHtml = '<iframe id="' + frameId + '" name="' + frameId + '" style="position:absolute; top:-9999px; left:-9999px"';
 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) {
 //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);
  }
 }
 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 = new Date().getTime() 
 var form = jQuery.createUploadForm(id, s.fileElementId, (typeof(s.data)=='undefined'?false:s.data));
 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?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 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 () {}}; 
 },

 uploadHttpData: function( r, type ) {
 var data = !type;
 data = type == "xml" || data ? 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" )
  eval( "data = " + data );
 // evaluate scripts within html
 if ( type == "html" )
  jQuery("<div>").html(data).evalScripts();
 return data;
 }
})