jquery怎样实现ajax联动框(一)

前台页面

<script type="text/javascript" src="${rc.contextPath}/js/jquery.select.js"></script> 
<script type="text/javascript"> 
$(document).ready(function(){ 
$("#rwflSelect").linkSelect({ 
nodata:"none", 
required:true, 
firstUrl:'${rc.contextPath}/repair/loadCategory', 
secondUrl:'${rc.contextPath}/repair/loadSubCategory', 
firstValue:'$!{repair.categoryid}',//任务大类 
secondValue:'$!{repair.subcategoryid}'//人物小类 
}); 
}); 
</script> 
<tr id="rwflSelect"> 
<td width="100" class="t_r prten field_c">任务分类：</td> 
<td width="131"><select class="first" name='categoryid'></select> </td> 
<td width="10"></td> 
<td width="131"><select class="second" name="subcategoryid" disabled="disabled"></select></td> 
</tr>

附
jquery.select.js

/* 
Ajax 三级联动 
日期：2013-2-26 
settings 参数说明 
----- 
firstUrl:一级下拉数据获取URL,josn返回 
firstValue:默认一级下拉value 
secondUrl:二级下拉数据获取URL,josn返回 
secondValue:默认二级下拉value 
thirdUrl:三级下拉数据获取URL,josn返回 
thirdValue:默认三级下拉value 
nodata:无数据状态 
required:必选项 
------------------------------ */ 
(function($){ 
$.fn.linkSelect=function(settings){ 
if($(this).size()<1){return;}; 
// 默认值 
settings=$.extend({ 
firstUrl:"js/city.min.js", 
firstValue:null, 
secondValue:null, 
thirdValue:null, 
nodata:null, 
required:true 
},settings); 
var box_obj=this; 
var first_obj=box_obj.find(".first"); 
var second_obj=box_obj.find(".second"); 
var third_obj=box_obj.find(".third"); 
var select_prehtml=(settings.required) ? "" : "<option value=''>请选择</option>"; 
var prepareSelectHtml=function(jsonArray){ 
var temp_html=select_prehtml; 
$.each(jsonArray,function(index,row){ 
temp_html+="<option value='"+row.value+"'>"+row.text+"</option>"; 
}); 
return temp_html; 
}; 
// 赋值二级下拉框函数 
var secondStart=function(){ 
second_obj.empty().attr("disabled",true); 
third_obj.empty().attr("disabled",true); 
if(first_obj.val()==''){ 
return; 
} 
$.getJSON(settings.secondUrl, { firstValue: first_obj.val(), time: new Date().getTime() }, function(jsonResult){ 
if(!jsonResult.success){ 
if(settings.nodata=="none"){ 
second_obj.css("display","none"); 
third_obj.css("display","none"); 
}else if(settings.nodata=="hidden"){ 
second_obj.css("visibility","hidden"); 
third_obj.css("visibility","hidden"); 
}; 
return; 
} 
// 遍历赋值二级下拉列表 
second_obj.html(prepareSelectHtml(jsonResult.data)).attr("disabled",false).css({"display":"","visibility":""}); 
thirdStart(); 
}); }; 
// 赋值三级下拉框函数 
var thirdStart=function(){ 
third_obj.empty().attr("disabled",true); 
$.getJSON(settings.thirdUrl, { firstValue: first_obj.val(),secondValue:second_obj.val(), time: new Date().getTime() }, function(jsonResult){ 
if(!jsonResult.success){ 
if(settings.nodata=="none"){ 
third_obj.css("display","none"); 
}else if(settings.nodata=="hidden"){ 
third_obj.css("visibility","hidden"); 
}; 
return; 
} 
// 遍历赋值三级下拉列表 
third_obj.html(prepareSelectHtml(jsonResult.data)).attr("disabled",false).css({"display":"","visibility":""}); 
thirdStart(); 
}); 
}; 
var init=function(){ 
// 遍历赋值一级下拉列表 
$.getJSON(settings.firstUrl, {time: new Date().getTime() }, function(jsonResult){ 
if(!jsonResult.success){ 
return; 
} 
// 遍历赋值一级下拉列表 
first_obj.html(prepareSelectHtml(jsonResult.data)); 
secondStart(); 
// 若有传入一级与二级的值，则选中。（setTimeout为兼容IE6而设置） 
setTimeout(function(){ 
if(settings.firstValue && settings.firstValue.length>0){ 
first_obj.val(settings.firstValue); 
secondStart(); 
setTimeout(function(){ 
if(settings.secondValue && settings.secondValue.length>0){ 
second_obj.val(settings.secondValue); 
thirdStart(); 
setTimeout(function(){ 
if(settings.thirdValue && settings.thirdValue.length>0){ 
third_obj.val(settings.thirdValue); 
}; 
},1); 
}; 
},1); 
}; 
},1); 
}); 
// 选择一级时发生事件 
first_obj.bind("change",function(){ 
secondStart(); 
}); 
// 选择二级时发生事件 
second_obj.bind("change",function(){ 
thirdStart(); 
}); 
}; 
// 初始化第一个下拉框 
init(); 
}; 
})(jQuery);

${rc.contextPath}/repair/loadCategory 对应的后台方法及返回json值：

@RequestMapping("loadCategory") 
@ResponseBody 
public Map<String, Object> loadCategory(ModelMap model){ 
String msg = ""; 
boolean isSuccess = false; 
List<Map<String, String>> maps=new ArrayList<Map<String,String>>(); 
try { 
List<Category> categories= categoryService.findAllCategory(); 
for (Category category : categories) { 
Map<String,String> map=new HashMap<String, String>(); 
map.put("value", category.getId().toString()); 
map.put("text", category.getCategoryName()); 
maps.add(map); 
} 
msg = "查找大类成功。"; 
isSuccess=true; 
} catch (Exception e) { 
msg = "查找大类失败。"; 
log.error("查找大类失败：" + e.getMessage(), e); 
} 
return buildAjaxResult(isSuccess, msg,maps); 
} 
protected Map<String, Object> buildAjaxResult(boolean isSuccess, String msg, Object data) { 
Map<String, Object> resultMap = new HashMap<String, Object>(); 
resultMap.put("success", isSuccess); 
resultMap.put("msg", msg); 
resultMap.put("data", data); 
return resultMap; 
}

效果如图：