spring - 在 Spring MVC 中动态填充下拉列表

Question

我是 Spring MVC 的新手。我在 Jsp.One 中有两个下拉列表用于国家和其他国家。一旦我从列表中选择国家，国家列表应该填充相应的列表。

我的ajax程序:

 $("select#country").change(function() {
    var val=$("#country").val();
    alert(val);
    $.ajax({
    url : 'getstates',
    method : 'get',
    contentType: 'application/json',
     data :{
              country : val
            },

      success: function (data) {
      alert("Success Response"+ data);

      },

       error :function()
       {
               alert("error");
        }          

       });

我的 Controller 程序:

 public @ResponseBody HashMap<String, String> 
    showstates(@RequestParam(required = false, value =      "") 
    String country,@Valid    @ModelAttribute("employee")Login employee, 
    BindingResult result, ModelMap model) {  
    HashMap<String,String>  statelist = new HashMap<String,String>();
    List<States> statelist = new ArrayList<States>();
    if (country.equals("UnitedStates")) {
    statelist.put("Al","Alaska");
    statelist.put("Tl","Texas");
    } else if (country.equals("India")) {
    statelist.put("Mh","Maharashtra");
    statelist.put("WB","West Bengal");
    statelist.put("KR","Karnataka");
    statelist.put("AP","Andhra Pradesh");
    statelist.put("TN","Tamil Nadu");
    } 
    return statelist;
    }  

我没有得到 Controller 的响应。 jsp中如何访问hasmap。请帮我。谢谢。

Answer 1

我认为你应该改变你的方法，如下所示。

@RequestMapping(value = "/getstates", method = RequestMethod.GET)
public @ResponseBody HashMap<String, String>  showstates(@RequestParam(required = false, value = "") 
    String country,@Valid    @ModelAttribute("employee")Login employee, 
    BindingResult result, ModelMap model) {  
    HashMap<String,String>  stateMap = new HashMap<String,String>();
    //put your logic to add state on basis of country

    return stateMap;
    }  

然后在 JSP 上，您可以简单地迭代此映射，如下所示。

<c:forEach items="${state.stateMap}" var="data" varStatus="status">
            <tr>
                <td>${data.value}</td>
            </tr>
        </c:forEach>