<select class="form-control zz-set-input-size" id="channel">
<option value="">请选择</option>
<option th:each="channel,index:${allChannels}" th:value="${channel.key}" th:text="${channel.value}"></option>
</select>
map的两个属性:key和value
<select class="form-control zz-set-input-size" id="channel">
<option value="">请选择</option>
<option th:each="channel,index:${allChannels}" th:value="${channel.key}" th:text="${channel.value}"></option>
</select>
map的两个属性:key和value