$.ajax({
				type : 'POST',url : '<%=basePath %>user/getOrgRoles.do',data : {'orgId' : orgId},async: false,contentType: "application/json; charset=utf-8",dataType : 'json',success : function(data){
					
				},error : function(XMLHttpRequest,textStatus,errorThrown) {
				}
			}); 

后台代码：

@ResponseBody
	@RequestMapping("/getOrgRoles") 
	public Object getOrgRoles(@RequestParam(value = "orgId",required = true) String orgId) {

	    List<TempUser> tempUserList = null;
	    JSONObject jsonObjectFromMap = null;
	    try
        {
	        tempUserList = tempUserService.getOrgRole(Long.parseLong(orgId));
	        jsonObjectFromMap = JSONObject.fromObject(tempUserList); 
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
	    
	    return jsonObjectFromMap;
	}

问题出在：@RequestParam 不能接收 contentType : "application/json; charset=utf-8" 的请求。

如果后台必须要用@RequestParam，

前台2个地方必须改：

1、contentType 改为"application/x-www-form-urlencoded"

2、data: 改为{'orgId':orgId},