swfupload多图上传限制图片张数

$.swfUpload({
            id: 'spanButtonPlaceholder',
            post_params: {
                'type': 'msg_flow',
                'subType': 'h'
            },
            isShowLoadImg: false,
            file_upload_limit: "6",

            upload_success_handler: uploadSuccess,
            file_queue_error_handler: uploadError,
            swfupload_loaded_handler : loaded,

            custom_settings: {
                upload_target: "divFileProgressContainer"
            }
        });

        function loaded() {
            var $imageDiv = $("#pic_list");
            var $imgList = $imageDiv.find("img");
            var stats = SWFUpload.instances.SWFUpload_1.getStats();
            stats.successful_uploads=$imgList.length;
            SWFUpload.instances.SWFUpload_1.setStats(stats);
        }

        function uploadError(file, code, message) {
            if (code == "-110") {
                alertmsg("文件大小超过" + "10M");
            } else if (code == "-130") {
                alertmsg(file.name + "文件类型不支持上传，将不会被上传");
            } else if (code == "-100") {
                alertmsg("图片上传数量超过" + 6 + "张，多余的不会上传");
            } else {
                console.log(code);
            }
        }
        function uploadSuccess(file, serverData) {
            addImage(serverData);

            var img = "";
            var $imageDiv = $("#pic_list");
            var $imgList = $imageDiv.find("img");
            for (var t = 0; t < $imgList.length; t++) {
                var $img = $($imgList[t]);
                img += $img.attr("src");
                if (t != $imgList.length - 1) {
                    img += ",";
                }
            }

            $('#imgList').val(img);

            var stats = SWFUpload.instances.SWFUpload_1.getStats();
            stats.successful_uploads=$imgList.length;
            SWFUpload.instances.SWFUpload_1.setStats(stats);
        }

        function addImage(serverData) {
            var jsonData = $.parseJSON(serverData);

            var src = jsonData.url;
            if (jsonData.error == -1) {
                $("#qwErrAlert").qwPopup({content: "图片格式错误！"});
                return;
            }

            var newElement = "<li style='float: left'><span class='del_img'><img onclick='bigPic(this);' class='upload_imgs'  src='" + src + "'><a class='button'></a></span></li>";
            $("#pic_list").append(newElement);
            $("a.button").bind("click", del);
        }

        var del = function () {
            $(this).parent().parent().remove();
            var src = $(this).siblings('img').attr('src');
            var img = "";
            var $imageDiv = $("#pic_list");
            var $imgList = $imageDiv.find("img");
            for (var t = 0; t < $imgList.length; t++) {
                var $img = $($imgList[t]);
                img += $img.attr("src");
                if (t != $imgList.length - 1) {
                    img += ",";
                }
            }
            $('#imgList').val(img);

            var stats = SWFUpload.instances.SWFUpload_1.getStats();
            stats.successful_uploads=$imgList.length;
            SWFUpload.instances.SWFUpload_1.setStats(stats);
        };

 html

 <tr id="mainImg">
    <th><em>*</em>正面图片:</th>
    <td>
	<div style="width: 500px; height: auto; border: 1px solid #e1e1e1; font-size: 12px; padding: 10px;">
	    <span id="spanButtonPlaceholder"></span>
	    <em id="emName9" style="display: none;">必须选择6张图片</em>
	    <div id="divFileProgressContainer"></div>
	    <div id="thumbnails">
		<ul id="pic_list" style="margin: 5px;"></ul>
		<div style="clear: both;"></div>
	    </div>
	</div>
	<input type="hidden" name="imgList" id="imgList" value=""/>
    </td>
</tr>