js 获取上传图片的绝对路径

function coursePptChange(){
  var MyTest = document.getElementById("pptPic").files[0];
  var reader = new FileReader();
  reader.readAsDataURL(MyTest);
  reader.onload = function(theFile) {
  var image = new Image();
  image.src = theFile.target.result;
  image.onload = function(){
  if(this.width > 2208 || this.height >1242){
  $.messager.alert("系统提示信息","ppt图片的最大宽度为 2208 像素，最大高度为 1242 像素！","info");
   $("#pptPic").val("");
  return false;
 }
 };
 };
}

jsp:

<input type="file" id="editPptPic" name="pptPic" style="width:200px;" onchange="coursePptChange()"/>