知识点：线程内唯一对象，其他类中使用session,SwfUpLoad以及selectImage插件的使用

图书商城项目-二

知识点：线程内唯一对象，其他类中使用session,SwfUpLoad以及selectImage插件的使用

线程内唯一对象

举个例子，比如我请求一个default.aspx页面，代码执行到事件管道的第11和12之间执行一个方法，这个方法开一个线程去执行某些逻辑，这个协程开启的方法会用到HttpContext对象

protected void Page_Load(object sender, EventArgs e)
        {
            ParameterizedThreadStart par = new
            ParameterizedThreadStart(GetFilePath);
            Thread thread1 = new Thread(par);
            thread1.IsBackground = true;
            thread1.Start(HttpContext.Current);
            //GetFilePath();

        }

  protected void GetFilePath(object context)
        {
            HttpContext context = (HttpContext)context;
        }

但是执行会发现报错：context为null，这是因为跨线程的HttpContext并不包含请求数据，但是如果你不开线程直接调用的话是没有问题的，因为这就相当于主线程调用。

要在其他类中使用session必须实现接口System.Web.SessionState.IRequiresSessionState

SwfUpLoad的使用

首先导入所需的文件，做好相关js的引用，下面是一个小demo测试，JS部分

<script type="text/javascript">
       var swfu;
       window.onload = function () {
           swfu = new SWFUpload({
               // Backend Settings
               upload_url: "/ashx/upload.ashx",//请求的页面
               post_params: {
                   "ASPSESSID": "<%=Session.SessionID %>"
               },

		    // File Upload Settings //配置，文件的格式大小等等
		    file_size_limit: "2 MB",
		    file_types: "*.jpg;*.gif",
		    file_types_description: "JPG Images",
		    file_upload_limit: 0,    // Zero means unlimited

		    // Event Handler Settings - these functions as defined in Handlers.js
		    //  The handlers are not part of SWFUpload but are part of my website and control how
		    //  my website reacts to the SWFUpload events.
		    swfupload_preload_handler: preLoad,
		    swfupload_load_failed_handler: loadFailed,
		    file_queue_error_handler: fileQueueError,
		    file_dialog_complete_handler: fileDialogComplete,
		    upload_progress_handler: uploadProgress,
		    upload_error_handler: uploadError,
		    upload_success_handler: showImage,
		    upload_complete_handler: uploadComplete,

		    // Button settings
		    button_image_url: "/SWFUpload/images/XPButtonNoText_160x22.png",
		    button_placeholder_id: "spanButtonPlaceholder",
		    button_width: 160,
		    button_height: 22,
		    button_text: '<span class="button">请选择上传图片<span class="buttonSmall">(2 MB Max)</span></span>',
		    button_text_style: '.button { font-family: Helvetica, Arial, sans-serif; font-size: 14pt; } .buttonSmall { font-size: 10pt; }',
		    button_text_top_padding: 1,
		    button_text_left_padding: 5,

		    //flash的按钮的路径
		    flash_url: "/SWFUpload/swfupload.swf",	// Relative to this file
		    flash9_url: "/SWFUpload/swfupload_FP9.swf",	// Relative to this file

		    custom_settings: {
		        upload_target: "divFileProgressContainer"//上传信息显示的区域
		    },

		    // Debug Settings
		    debug: false
		});
       }
       //上传成功以后调用该方法(改写的方法)
       function showImage(file, serverData) {//serverData即服务器返回的数据
           //$("#showPhoto").attr("src", serverData);
           $("#showPhoto").attr("src",serverData);
       }
</script>

Html部分

<div id="content">
           <div id="swfu_container" style="margin: 0px 10px;">
               <div>
                   aaaaaaa
                   <span id="spanButtonPlaceholder"></span>
                   aaaaaa
               </div>
               ssssssssssssss
               <div id="divFileProgressContainer" style="height: 75px;"></div>
               sssssssssss
               <div id="thumbnails"></div>
               <img id="showPhoto"></img>
           </div>
       </div>

服务器处理的aspx要注意，服务器返回图片的地址不能是物理路径，只有保存的时候需要物理路径

imgAreaSelect插件实现图片裁剪

剪裁示例：https://www.cnblogs.com/mizzle/archive/2011/10/13/2209891.html