javaSpringMVC上传文件（图片、文档、视频）及在线浏览

servlet上传文件：https://blog.youkuaiyun.com/baidu_35468322/article/details/88871675
上传（jsp）：

<form action="caseKnowledge/${msg }.do" name="ckForm" id="ckForm" method="post" enctype="multipart/form-data">
	<input type="hidden" name="ck_belong" value="${CK_BELONG }"/>
	<input type="hidden" name="ck_id" id="ck_id" value="${pd.CK_ID }"/>
	<table id="table_report" class="table table-striped table-bordered table-hover">
		<c:if test="${fx != 'head'}">
		<tr>
			<td style="width:79px;text-align: right;padding-top: 13px;">类型:</td>
			<td id="tp_ids">
				<select class="chosen-select form-control" name="tp_id" id="tp_id" data-placeholder="请选择类型" style="vertical-align:top;" style="width:98%;" >
				<option value=""></option>
				<c:forEach items="${tpList}" var="tp">
					<option value="${tp.TP_ID }" <c:if test="${tp.TP_ID == pd.TP_ID }">selected</c:if>>${tp.TP_NAME }</option>
				</c:forEach>
				</select>
			</td>
		</tr>
		</c:if>
		<tr>
			<td style="width:79px;text-align: right;padding-top: 13px;">标题:</td>
			<td><input type="text" name="ck_title" id="ck_title" value="${pd.CK_TITLE }" maxlength="32" placeholder="这里输入标题" title="标题" style="width:98%;"/></td>
		</tr>
		<tr>
			<td style="width:79px;text-align: right;padding-top: 13px;">简介:</td>
			<td><input type="text" name="ck_blurb" id="ck_blurb" value="${pd.CK_BLURB }" maxlength="32" placeholder="这里输入简介" title="简介" style="width:98%;"/></td>
		</tr>
		<tr id="attach_type">
			<td style="width:79px;text-align: right;padding-top: 13px;">附件类型:</td>
			<td>
				<select name="ck_attach_type" id="ck_attach_type" placeholder="附件类型" title="附件类型" style="width:98%;">
					<option value="">请选择附件类型</option>
					<option value="0">图片</option>
					<option value="1">视频</option>
					<option value="2">文档</opti