select菜单实现二级联动

<tr>
<th>执行人<b>*</b></th>
<td>
<select name="jdcld.ZXDW" id="zxrDw" onchange="zxDwChange()" class="select" style="width:230px">
<option value="">选择部门</option>
<#if zxrBm??&&zxrBm?size!=0>
<#list zxrBm as bm>
<option value="${bm['id']}">${bm['mc']}</option>
</#list>
</#if>
</select>
<select name="jdcld.ZXRID" id="zxrId" class="select" style="width:230px">
<option value="">选择民警</option>
</select>
<input type="hidden" name="jdcld.ZXRXM"/>
</td>
</tr>

function zxDwChange() {
var bmid = $("#zxrDw").val();
alert(bmid);
$("#zxrId").empty();
var text = "<option value=''>选择民警</option>";
$.post("${base}/zfjd/zxrList", {"bmid":bmid}, function(data) {
if (data != "") {
var dataArr = eval('(' + data + ')');
for (var i in dataArr) {
text += "<option value='" + dataArr[i].value + "'>" + dataArr[i].title + "</option>";
}
if (text == "<option value=''>选择民警</option>") {
$("#zxrId").append("<option value=''>选择民警</option>");
} else
$("#zxrId").append(text);
} else {
$("#zxrId").append("<option value=''>选择民警</option>");
}
});
}

@Action("zxrList")
public void zxrList() {
try {
if (request.getParameter("bmid").equals("")) {

} else {
Integer bmid = Integer.parseInt(request.getParameter("bmid"));
zxr = policeMenService.getZxr(bmid);
String json = "[";
if (null != zxr && zxr.size() > 0) {
for (Map map : zxr) {
json += "{\"value\":\"" + map.get("id") + "\",\"title\":\"" + map.get("xm") + "\"},";
}
json = json.substring(0, json.length() - 1);
}
json += "]";
super.renderText(json);
}
} catch (Exception e) {
e.printStackTrace();
}
}