基于ajax实现上传图片代码示例解析

/// <reference path="jquery-1.8.3.js" /> 
/// <reference path="ajaxForm/jquery.form.js" /> 
 
/*! 
 * jQuery upload 
 * 用于上传单个文件，上传成功后,返回文件路径。 
 * 本插件依赖jQuery，jquery.form 请在使用时引入依赖的文件 
 * 
 * Date: 2014/4/23 
 */ 
/* 
使用: 
html: 
<div style="width: 100%; float: left;"> 
  <input type="hidden" id="hfThumbnail" value="/uploads/2014/04/23/635338686611432716.jpg" /> 
  <div class="imgdiv"></div> 
  <span class="img_span"> 
    <input type="file" name="file" /> 
  </span> 
   
  <input type="button" value="上传" class="upload" /> 
</div> 
<div style="width: 100%; float: left;"> 
  <input type="hidden" id="hfThumbnail" value="/uploads/2014/04/23/635338686611432716.jpg" /> 
  <div class="imgdiv"></div> 
  <span class="img_span"> 
    <input type="file" name="file" /> 
  </span> 
   
  <input type="button" value="上传" class="upload" /> 
</div> 
 
js: 
 
$(document).ready(function () { 
     
  //$(".upload").upload({ 
  //  uploadData: { id: "12233" }, 
  //  successFn: function (response, statusText, xhr, $this) { 
  //    alert(response.Data.RelativePath) 
  //  }, 
  //  deleteData: { id: function () { return "asdfasdf" } } 
  //}); 
  
  $(".upload").upload({ 
    uploadData: { id: "12233" }, 
    successFn: "success",      //可以是字符串 
    deleteData: { id: function () { return "asdfasdf" } } 
  }); 
}); 
 
//上传成功后执行该函数 
function success(response, statusText, xhr, $this) { 
  //比如插入编辑器 
  alert(response.Data.RelativePath + $this.attr("value")) 
} 
*/ 
 
(function ($) { 
  $.extend($.fn, { 
    upload: function (settings) { 
 
      var options = $.extend({ 
        fileType: "gif|jpg|jpeg|png|bmp",            //允许的文件格式 
        uploadUrl: "/ajax/handler.ashx?action=uploadfile",   //上传URL地址 
        deleteUrl: "/ajax/handler.ashx?action=deletefile",   //删除URL地址 
        width: "",                       //图片显示的宽度 
        height: 100,                      //图片显示的高度 
        imgSelector: ".imgdiv",                 //图片选择器 
        uploadData: {},                     //上传时需要附加的参数 
        deleteData: {},                     //删除时需要附加的参数 
        deleteFn: function ($parent, showMessage) {       //删除图片的方法(默认方法使用POST提交) 
          methods.deleteImage($parent, showMessage); 
        }, 
        beforeSubmitFn: "beforeUpload",             //上传前执行的方法 原型 beforeSubmit(arr, $form, options); 
        successFn: "uploadSuccess",               //上传成功后执行的方法 uploadSuccess(response, statusText, xhr, $this) 
        errorFn: "uploadError"                 //上传失败后执行的方法 
      }, settings); 
 
      //上传准备函数 
      var methods = { 
        //验证文件格式 
        checkFile: function (filename) { 
          var pos = filename.lastIndexOf("."); 
          var str = filename.substring(pos, filename.length); 
          var str1 = str.toLowerCase(); 
          if (typeof options.fileType !== 'string') { options.fileType = "gif|jpg|jpeg|png|bmp"; } 
          var re = new RegExp("\.(" + options.fileType + ")$"); 
          return re.test(str1); 
        }, 
        //创建表单 
        createForm: function () { 
          var $form = document.createElement("form"); 
          $form.action = options.uploadUrl; 
          $form.method = "post"; 
          $form.enctype = "multipart/form-data"; 
          $form.style.display = "none"; 
          //将表单加当document上， 
          document.body.appendChild($form); //创建表单后一定要加上这句否则得到的form不能上传。document后要加上body,否则火狐下不行。 
          return $($form); 
        }, 
        //创建图片 
        createImage: function () { 
          //不能用 new Image() 来创建图片，否则ie下不能改变img 的宽高 
          var img = $(document.createElement("img")); 
          img.attr({ "title": "双击图片可删除图片！" }); 
          if (options.width !== "") { 
            img.attr({ "width": options.width }); 
          } 
          if (options.height !== "") { 
            img.attr({ "height": options.height }); 
          } 
          return img; 
        }, 
        showImage: function (filePath, $parent) { 
          var $img = methods.createImage(); 
          $parent.find(options.imgSelector).find("img").remove(); 
          //要先append再给img赋值，否则在ie下不能缩小宽度。 
          $img.appendTo($parent.find(options.imgSelector)); 
          $img.attr("src", filePath); 
          this.bindDelete($parent); 
        }, 
        bindDelete: function ($parent) { 
          $parent.find(options.imgSelector).find("img").bind("dblclick", function () { 
            options.deleteFn($parent, true); 
          }); 
        }, 
        deleteImage: function ($parent, showMessage) { 
          var $fileInput = $parent.find("input:hidden"); 
          if ($fileInput.val() !== "") { 
 
            var data = $.extend(options.deleteData, { filePath: $fileInput.val(), t: Math.random() }); 
 
            $.post(options.deleteUrl, data, function (response) { 
 
              if (showMessage) { alert(response.MessageContent) } 
 
              if (response.MessageType == 1) { 
                $fileInput.val(""); 
                $parent.find(options.imgSelector).find("img").remove(); 
              } 
            }, "JSON"); 
          } 
        }, 
        onload: function ($parent) { 
          var hiddenInput = $parent.find("input:hidden"); 
          if (typeof hiddenInput !== "undefined" && hiddenInput.val() !== "") { 
            var img = methods.createImage(); 
            if ($parent.find(options.imgSelector).find("img").length > 0) { $parent.find(options.imgSelector).find("img").remove(); } 
            //要先append再给img赋值，否则在ie下不能缩小宽度。  
            img.appendTo($parent.find(options.imgSelector)); 
            img.attr("src", hiddenInput.val()); 
            methods.bindDelete($parent); 
          } 
        } 
      }; 
      //上传主函数 
      this.each(function () { 
        var $this = $(this); 
        methods.onload($this.parent()); 
        $this.bind("click", function () { 
          var $fileInput = $(this).parent().find("input:file"); 
          var fileBox = $fileInput.parent(); 
 
          if ($fileInput.val() === "") { 
            alert("请选择要上传的图片！"); 
            return false; 
          } 
          //验证图片 
          if (!methods.checkFile($fileInput.val())) { 
            alert("文件格式不正确，只能上传格式为：" + options.fileType + "的文件。"); 
            return false; 
          } 
          //若隐藏域中有图片，先删除图片 
          if ($fileInput.val() !== "") { 
            options.deleteFn($this.parent(), false); 
            //methods.deleteImage($this.parent(), false); 
          } 
 
          //创建表单 
          var $form = methods.createForm(); 
 
          //把上传控件附加到表单 
          $fileInput.appendTo($form); 
          fileBox.html("<img src=\"/admin/styles/images/loading.gif\" />  正在上传... "); 
          $this.attr("disabled", true); 
 
          //构建ajaxSubmit参数 
          var data = {}; 
          data.data = options.uploadData; 
          data.type = "POST"; 
          data.dataType = "JSON"; 
          //上传前 
          data.beforeSubmit = function (arr, $form, options) { 
 
            var beforeSubmitFn; 
            try { beforeSubmitFn = eval(options.beforeSubmitFn) } catch (err) { }; 
            if (beforeSubmitFn) { 
              var $result = beforeSubmitFn(arr, $form, options); 
              if (typeof ($result) == "boolean") 
                return $result; 
            } 
          }; 
          //上传失败 
          data.error = function (response, statusText, xhr, $form) { 
            var errorFn; 
            try { errorFn = eval(options.errorFn) } catch (err) { }; 
            if (errorFn) { 
              errorFn(response.responseText, statusText, xhr, $this); 
            } 
          }; 
          //上传成功 
          data.success = function (response, statusText, xhr, $form) { 
            //response = eval("(" + response + ")"); 
            if (response.MessageType == 1) { 
              methods.showImage(response.Data.RelativePath, $this.parent()); 
              $this.parent().find("input:hidden").val(response.Data.RelativePath); 
 
              var successFn; 
              try { successFn = eval(options.successFn) } catch (err) { }; 
              if (successFn) { 
                $.ajaxSetup({ cache: false });//这个不能少，否则ie下会提示下载 
                successFn(response, statusText, xhr, $this); 
              } 
 
 
            } else { 
              alert(response.MessageContent); 
            } 
            $this.attr("disabled", false); 
            fileBox.html("<input type=\"file\" name=\"file\" />"); 
            $form.remove(); 
          }; 
 
          try { 
            //开始ajax提交表单 
            $form.ajaxSubmit(data); 
          } catch (e) { 
            alert(e.message); 
          } 
        }); 
      }); 
    } 
  }); 
})(jQuery) 

<!DOCTYPE html> 
 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head runat="server"> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
<script src="Scripts/jquery/jquery-1.8.3.js"></script> 
<script src="Scripts/jquery/ajaxForm/jquery.form.js"></script> 
<script src="Scripts/jquery/jquery.upload.js"></script> 
<title></title> 
</head> 
<body> 
<form id="form1" runat="server"> 
<div style="width: 100%; float: left;"> 
  <input type="hidden" id="hfThumbnail" value="/uploads/2014/04/23/635338686611432716.jpg" /> 
  <div class="imgdiv"></div> 
  <span class="img_span"> 
    <input type="file" name="file" /> 
  </span> 
    
  <input type="button" value="上传" class="upload" /> 
</div> 
<div style="width: 100%; float: left;"> 
  <input type="hidden" id="hfThumbnail" value="/uploads/2014/04/23/635338686611432716.jpg" /> 
  <div class="imgdiv"></div> 
  <span class="img_span"> 
    <input type="file" name="file" /> 
  </span> 
    
  <input type="button" value="上传" class="upload" /> 
</div> 
</form> 
<script type="text/javascript"> 
  $(document).ready(function () { 
    //$(".upload").upload({ 
    //  uploadData: { id: "12233" }, 
    //  successFn: function (response, statusText, xhr, $this) { 
    //    alert(response.Data.RelativePath) 
    //  }, 
    //  deleteData: { id: function () { return "asdfasdf" } } 
    //}); 
    $(".upload").upload({ 
      uploadData: { id: "12233" }, 
      successFn: "success", 
      deleteData: { id: function () { return "asdfasdf" } } 
    }); 
  }); 
 
  //上传成功后执行该函数 
  function success(response, statusText, xhr, $this) { 
    //比如插入编辑器 
    alert(response.Data.RelativePath + $this.attr("value")) 
  } 
</script> 
</body> 
</html> 

public void ProcessRequest(HttpContext context) 
{ 
  context.Response.ContentType = "application/json"; 
  var action = context.Request.QueryString.Get<string>("action").ToLower(); 
  var response = new JsonResult(StatusMessageType.Error, "没有权限或无效请求。").ToJson(); 
  switch (action) 
  { 
 
    case "uploadfile": 
      if (context.Request.Files.Count > 0) 
        response = UploadFile(context.Request); 
      break; 
    case "deletefile": 
      response = DeleteFile(context.Request.Form); 
      break; 
    default: 
      break; 
  } 
  context.Response.Write(response); 
} 
/// <summary> 
///  
/// </summary> 
/// <param name="file"></param> 
/// <returns></returns> 
private string UploadFile(HttpRequest request) 
{ 
  if (request.Files.Count == 0) 
    return new JsonResult(StatusMessageType.Error, "没有可处理的数据。").ToJson(); 
  var id = request.Form.Get<string>("id", ""); 
 
  var file = request.Files[0]; 
  if (file == null || file.ContentLength <= 0 || string.IsNullOrEmpty(file.FileName)) 
    return new JsonResult(StatusMessageType.Error, "没有可处理的数据。").ToJson(); 
 
  //IStoreFile storeFile = null; 
 
  string[] datePaths = new string[] { "~/uploads/" }; 
  datePaths = datePaths.Union(DateTime.Now.ToString("yyyy-MM-dd").Split('-')).ToArray(); 
  var relativePath = storeProvider.JoinDirectory(datePaths); 
 
  var dirPath = HttpContext.Current.Server.MapPath(relativePath); 
 
  if (!System.IO.Directory.Exists(dirPath)) 
    System.IO.Directory.CreateDirectory(dirPath); 
 
  var fileName = GenerateFileName(Path.GetExtension(file.FileName)); 
 
  var filePath = Path.Combine(dirPath, fileName); 
  file.SaveAs(filePath); 
  return new JsonResult(StatusMessageType.Success, "上传成功。", new 
  { 
    RelativePath = WebUtility.ResolveUrl(Path.Combine(relativePath, fileName)), 
    Size = file.ContentLength, 
    Id = id, 
  }).ToJson(); 
} 
 
public string DeleteFile(NameValueCollection form) 
{ 
  var filePath = form.Get<string>("filePath", "").Trim(); 
  if (string.IsNullOrEmpty(filePath)) 
    return new JsonResult(StatusMessageType.Error, "无效提交。").ToJson(); 
 
  try 
  { 
    if (System.IO.File.Exists(HttpContext.Current.Server.MapPath(filePath))) 
    { 
      System.IO.File.Delete(HttpContext.Current.Server.MapPath(filePath)); 
      return new JsonResult(StatusMessageType.Success, "文件删除成功。").ToJson(); 
    } 
    else 
    { 
      return new JsonResult(StatusMessageType.Success, "找不到该文件。").ToJson(); 
    } 
  } 
  catch (Exception) 
  { 
    return new JsonResult(StatusMessageType.Hint, "发生错误。").ToJson(); 
  } 
} 
 
/// <summary> 
/// 生成随机文件名 
/// </summary> 
/// <returns></returns> 
private string GenerateFileName(string extension) 
{ 
  return DateTime.Now.Ticks.ToString() + extension; 
} 

[Serializable] 
public class JsonResult 
{ 
  private StatusMessageType _messageType; 
  private string _messageContent; 
 
 
  /// <summary> 
  ///  
  /// </summary> 
  /// <param name="messageType"></param> 
  /// <param name="messageContent"></param> 
  /// <param name="data"></param> 
  public JsonResult(StatusMessageType messageType, string messageContent, object data = null) 
  { 
    _messageType = messageType; 
    _messageContent = messageContent; 
    Data = data; 
  } 
 
  public StatusMessageType MessageType 
  { 
    get { return _messageType; } 
    set { _messageType = value; } 
  } 
 
  public string MessageContent 
  { 
    get { return _messageContent; } 
    set { _messageContent = value; } 
  } 
 
  public object Data { get; set; } 
 
  public string ToJson() 
  { 
    JavaScriptSerializer serializer = new JavaScriptSerializer(); 
    var json = serializer.Serialize(this); 
 
    //string p = @"\\/Date(\d+)\\/"; 
    //MatchEvaluator matchEvaluator = new MatchEvaluator(ConvertJsonDateToDateString); 
    //Regex reg = new Regex(p); 
    //json = reg.Replace(json, matchEvaluator); 
    return json; 
  } 
 
  private static string ConvertJsonDateToDateString(Match m) 
  { 
    string result = string.Empty; 
    DateTime dt = new DateTime(1970, 1, 1); 
    dt = dt.AddMilliseconds(long.Parse(m.Groups[1].Value)); 
    dt = dt.ToLocalTime(); 
    result = dt.ToString("d"); 
    return result; 
  } 
} 

/// <summary> 
/// 提示消息类别 
/// </summary> 
public enum StatusMessageType 
{ 
  /// <summary> 
  /// 权限不足 
  /// </summary> 
  NoAccess = -2, 
  /// <summary> 
  /// 错误 
  /// </summary> 
  Error = -1, 
  /// <summary> 
  /// 成功 
  /// </summary> 
  Success = 1, 
 
  /// <summary> 
  /// 提示信息 
  /// </summary> 
  Hint = 0 
}