前端引入文件

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css">
<script src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="http://malsup.github.com/jquery.form.js"></script>

Ajax进度条异步处理

<script type="text/javascript">
$(function () {
      $("#myupload").ajaxForm({
          dataType:'json',
          beforeSend:function(){ 
                  $(".progress").show();
          },
          uploadProgress:function(event,position,total,percentComplete){
                  var percentVal = percentComplete + '%';
                  $(".progress-bar").width(percentComplete + '%');
                  $(".progress-bar").html(percentVal);
                  $(".sr-only").html(percentComplete + '%');
          },
          success:function(data){
                  $(".progress").hide();
          
                  if(data.error == "empty_name"){
                          alert("文件上传非法,上传失败!");
                          exit();
                  };
                  if(data.error == "large"){
                          alert("图片上传不能大于2M,上传失败!");
                          exit();
                  };
  
  /*alert(data.error);*/
                  if(data.error == "format"){
                          alert("图片格式错误,上传失败");
                          //alert(data.type);
                          exit();
                  };
  
                  //alert("上传成功!");
                  //files.html("<b>"+data.name+"("+data.size+"k)</b> <span class='delimg' rel='"+data.pic+"'>删除</span>");
                  $(".files").html("文件名: "+data.name+"<span class='delimg' rel='"+data.pic+"'>   del   </span>大小："+data.size);
                  var img = "http://www.sandleft.com/test/input/upload/files/"+data.pic;
                  $(".showimg").html("<img src='"+img+"'>");
                  alert("上传成功!");
          },
          error:function(){
                  alert("图片上传失败");
          }
          
      });
      $(".progress").hide();
});

</script>

前端上传HTML

 <div class="uk-container uk-container-center">

                <div class="pk-system-messages"></div>

				<h2 class="uk-h3 uk-text-center" >文件上传</h2>
				<div class="pk-system-messages"></div>

				 <div class="container-main">
         			 <h2>Ajax Image Uploader</h2>
         			 <p>A simple tutorial to explain p_w_picpath uploading using jquery ajax and php</p>
  
          			<form id='myupload' action='new_upload.php' method='post' enctype='multipart/form-data'>
          			  <label for="file">Filename:</label>
         			  <input type="file" name="mypic" id="file"><br>
         			  <input type="submit" name="upload" class="btn btn-success" value="upload">
         		    </form>
  
          		     <div class="progress">
          		       <div class="progress-bar progress-bar-success progress-bar-striped" role="progressbar" aria-valuenow="45" aria-valuemin="0" aria-valuemax="100" >
							<span class="sr-only">0% Complete</span>
         		       </div>
        		     </div>
					<div class="files"></div>
					<div class="showimg"></div>
                 </div>
				 
			 </div>

PHP文件上传类

<?php
class upload{

	protected $file_path = "files"; //当前files存储文件夹
	#protected $file_size = 1024000;
	protected $file_size = 5120000; //5M 用户上传
	//检测文件是否为空
 public function check_file($get_file)
 {
	   if (empty($get_file))
	   {
	     $type = "check_file";
             $arr = array('error'=>'empty_name','type'=>$type);
             echo json_encode($arr);
             exit();
        }
	return true;
}


 //检测文件类型
 public function check_type($get_type)
 {
	  if (( $get_type == ".docx" ) || ( $get_type == ".doc" )) {
	       #$types = $get_type;
	  }else{
	       $type = "check_type";
	       $arr = array('error'=>'format','type'=>$type);
               echo json_encode($arr);
               exit();	

     }
   return true;
 }

 //检测文件大小
 public function check_size($get_file)
 {
	 if ( $get_file != "" ) {
            if ( $get_file > $this->file_size ) {
                   $arr = array('error'=>'large');
                   echo json_encode($arr);
                   exit();
            }
    }else{
		return false;
		exit();
	}
  return true;
 }
   
//文件保存
 public function save_file($file_type,$file_tmp_name)
 {
	$rand = rand(1000, 9999);
	$pics = date("YmdHis") . $rand . $file_type;
	$path = $this->file_path."/".$pics;
	$result = move_uploaded_file($file_tmp_name, $path);
	if($result){
		return $pics;
	}else{
		return false;
		exit();
	}
	#return $pics;
 }
 
}

PHP文件上传处理

<?php
include("upload.class.php");
$up_obj = new upload();
 
$get_fileName = $_FILES['mypic']['name'];
$get_fileSize = $_FILES['mypic']['size'];
$get_TmpFiles = $_FILES['mypic']['tmp_name'];

$get_fileType = strstr($get_fileName, '.');

$check_result = $up_obj->check_file($get_fileName);

if($check_result){

    //检查文件类型
	$result_type = $up_obj->check_type($get_fileType);

	//检查文件大小
	if($result_type){

		$result_size = $up_obj->check_size($get_fileSize);

		if($result_size){
			//文件上传保存	
			$pics = $up_obj->save_file($get_fileType,$get_TmpFiles);		
			$size = round($get_fileSize/1024,2);
 	                $arr = array(
 		                'name' => $get_fileName,
		                 'pic' => $pics,
		                 'size'=> $size,
		                 'error' => 2
		         );

			 //检查文件上传状态
			 if($pics){
		         echo json_encode($arr);
				 /*
				 执行上传完成逻辑.....
				 */
			}		
		}
    }

}

文件上传效果如图：