JFinal使用ajaxfileupload实现图片上传及预览

本文实例为大家分享了JFinal使用ajaxfileupload实现图片上传预览的具体代码，供大家参考，具体内容如下

1.前端jsp页面核心代码

<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')"/>
<!--用于预览图片-->
<img src="<c:if test="${banner.img!=null}"><%=request.getContextPath() %>/media/file/${banner.img}</c:if>" style="width:300px;height:100px;" id="imgsrc"/>
<!--存放图片路径,提交页面时传给后台的值-->
<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("请先选择对应的上传文件，谢谢"); 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("上传失败");
   }
  }
 });
}

2.后台核心代码

public void uploadpic(){
 UploadFile upfile = getFile();//JFinal规定getFile()必须最先执行
 File file = upfile.getFile();
 String filename = file.getName();
 String delfilename = filename;
 if(filename!=null && !filename.equals("")){
  filename = new SimpleDateFormat("yyyyMMddkkmmss").format(new Date())+filename;
  /**
   * 新保存的位置
   */
  String path = getRequest().getSession().getServletContext()
    .getRealPath("/");
  String newPath = "/media/file/";//自定义目录 用于存放图片
  /**
   * 没有则新建目录
   */
  File floder = new File(path + newPath);
  if (!floder.exists()) {
   floder.mkdirs();
  }
  /**
   * 保存新文件
   */
  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();
   }
  }

  /**
   * 删除原图片，JFinal默认上传文件路径为 /upload（自动创建）
   */
  File delFile = new File(path+"/upload/"+delfilename);
  if(delFile.exists()){
   delFile.delete();
  }
  setAttr("msg",filename);
  setAttr("t",1);
 }else{
  setAttr("t",0);
 }
 renderJson();
}

附：ajaxfileupload.js代码

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;
 }
})

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。