ajax前后台交互实现省市区级联

1.html代码

<div class="row cl">
	<label class="form-label col-xs-4 col-sm-3">所在地址：</label>
	<div class="content">
	
		<span class="select-box pl-10" style="width:110px">
			<select id="province" class="select" onchange="select_citys(this)">
				<option  value = "">请选择</option>
				<!-- 循环显示所有省份 -->
				<#list provinces as province>
		    		<option <#if area?? && area.province.id == province.id>selected="selected"</#if> value="${province.id}">${province.placeZh}</option>
	    		</#list>
			</select>
		</span>

		<span class="select-box pl-10" style="width:110px">
			<select id="city" class="select" onchange="select_areas(this)">
				<#if area?? >
					<option value = "${area.city.id}">${area.city.placeZh}</option>
				<#else>
					<option value = "">请选择</option>
				</#if>
			</select>
		</span>

		<span class="select-box pl-10" style="width:110px">
			<select id="area" class="select">
				<#if area??>
					<option value = "${area.county.id}">${area.county.placeZh}</option>
				<#else>
					<option value = "">请选择</option>
				</#if>
			</select>
		</span>
		
	</div>
</div><div class="row cl">
	<label clas