html Bootstrap 折叠（Collapse）插件

<div class="panel-group" id="accordion">
	<div class="panel panel-default">
		<div class="panel-heading">
			<h4 class="panel-title">
				<a data-toggle="collapse" data-parent="#accordion" 
				   href="#collapseOne">
					点击我进行展开，再次点击我进行折叠。第 1 部分
				</a>
			</h4>
		</div>
		<div id="collapseOne" class="panel-collapse collapse in">
			<div class="panel-body">
				Nihil anim keffiyeh helvetica, craft beer labore wes anderson 
				cred nesciunt sapiente ea proident. Ad vegan excepteur butcher 
				vice lomo.
			</div>
		</div>
	</div>
	<div class="panel panel-default">
		<div class="panel-heading">
			<h4 class="panel-title">
				<a data-toggle="collapse" data-parent="#accordion" 
				   href="#collapseTwo">
					点击我进行展开，再次点击我进行折叠。第 2 部分
				</a>
			</h4>
		</div>
		<div id="collapseTwo" class="panel-collapse collapse">
			<div class="panel-body">
				Nihil anim keffiyeh helvetica, craft beer labore wes anderson 
				cred nesciunt sapiente ea proident. Ad vegan excepteur butcher 
				vice lomo.
			</div>
		</div>
	</div>
	<div class="panel panel-default">
		<div class="panel-heading">
			<h4 class="panel-title">
				<a data-toggle="collapse" data-parent="#accordion" 
				   href="#collapseThree">
					点击我进行展开，再次点击我进行折叠。第 3 部分
				</a>
			</h4>
		</div>
		<div id="collapseThree" class="panel-collapse collapse">
			<div class="panel-body">
				Nihil anim keffiyeh helvetica, craft beer labore wes anderson 
				cred nesciunt sapiente ea proident. Ad vegan excepteur butcher 
				vice lomo.
			</div>
		</div>
	</div>
</div>

　　更加简洁的例子:

<a class="btn btn-primary" role="button" data-toggle="collapse" href="#collapseExample" aria-expanded="false" aria-controls="collapseExample">
  Link with href
</a>
<button class="btn btn-primary" type="button" data-toggle="collapse" data-target="#collapseExample" aria-expanded="false" aria-controls="collapseExample">
  Button with data-target
</button>
<div class="collapse" id="collapseExample">
   这是折叠的内容
</div>