using System.Web;
using System.Web.Mvc;
using MvcApplication1.Models;

namespace MvcApplication1.Extension
{
    public class CustomerBinder : DefaultModelBinder
    {
        public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
        {
            if (bindingContext.ModelType == typeof (Customer))
            {
                HttpRequestBase request = controllerContext.HttpContext.Request;
                string province = request.Form.Get("Province");
                string city = request.Form.Get("City");
                string street = request.Form.Get("street");

                return new Customer() {Address = province+city+street};
            }
            else
            {
                return base.BindModel(controllerContext, bindingContext);
            }
            
        }
    }
}

using System.Web.Mvc;
using MvcApplication1.Extension;
using MvcApplication1.Models;

namespace MvcApplication1.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            return View();
        }

        [HttpPost]
        public ActionResult Index([ModelBinder(typeof(CustomerBinder))]Customer customer)
        {
            if (ModelState.IsValid)
            {
                return Content(customer.Address);
            }
            return View();
        }
    }
}

@{
    ViewBag.Title = "Index";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Index</h2>
@using (Html.BeginForm())
{
    <table>
        <tr>
            <td>省</td>
            <td><input type="text" id="Province" name="Province"/></td>
        </tr>
        <tr>
            <td>市</td>
            <td><input type="text" id="City" name="City"/></td>
        </tr>
        <tr>
            <td>街道</td>
            <td><input type="text" id="Street" name="Street"/></td>
        </tr>
        <tr>
            <td colspan="2"><input type="submit" value="提交"/></td>
        </tr>
    </table>
}