使用现有值更新 @ModelAttribute

Question

我想知道是否有办法更新现有的@ModelAttribute。如果可能，不保留会话中的值
假设我有一个 bean：

class TravelDetails{
    private String origin;
    private String destination;
    private String travelerName;
    private String travelerAge;
        // Getters & Seters
}

这是我的控制器：

@Controller
class TravelerController{

@RequestMapping(value="/searchDetails", method=RequestMethod.GET)
public ModelAndView getSearchDetails(@RequestParam("origin") String origin,
        @RequestParam("destination") String destination,ModelMap modelMap){
    TravelDetails travelDetails = new TravelDetails();
    travelDetails.setOrigin(origin);
    travelDetails.setDestination(destination);
    modelMap.addAttribute("travelDetails",travelDetails);
    return new ModelAndView("get_traveler_details");
    }

@RequestMapping(value="/addTravelerDetails", method=RequestMethod.POST)
public ModelAndView addTravelerDetails(
    @ModelAttribute("travelDetails") TravelDetails travelDetails,
           ModelMap modelMap){
    System.out.println(travelDetails.getOrigin);
    System.out.println(travelDetails.getDestination);
    System.out.println(travelDetails.getTravelerName);
    System.out.println(travelDetails.getTravelerAge);
    return new ModelAndView("get_traveler_details");
    }
   }

第二个控制器方法得到的post表单只包含旅行者的姓名和年龄，而出发地和目的地需要从第一个控制器中设置的模型属性中检索。
我不想在 Post 表单中显式设置隐藏字段。
假设我的 HTML 是：

<form:form modelAttribute="travelDetails" action="/addTravelerDetails" method="POST">
    <form:input type="text" path="travelerName"/>
    <form:input type="text" path="travelerAge"/>
</form:form>

注意：我是在 StackOverflow 的文本区域而不是在某些 IDE 上编写代码，所以如果代码中有一些蹩脚的拼写或语法错误，请忽略。

Answer 1

你可以在类级别使用@SessionAttributes注解

@Controller
@SessionAttributes("travelDetailsPersist")
class TravelerController{

    @RequestMapping(value="/searchDetails", method=RequestMethod.GET)
    public ModelAndView getSearchDetails(@RequestParam("origin") String origin, @RequestParam("destination") String destination,ModelMap modelMap){
        TravelDetails travelDetails = new TravelDetails();
        travelDetails.setOrigin(origin);
        travelDetails.setDestination(destination);
        modelMap.addAttribute("travelDetails",travelDetails);
        modelMap.addAttribute("travelDetailsPersist",travelDetails);
        return new ModelAndView("get_traveler_details");
    }

    @RequestMapping(value="/addTravelerDetails", method=RequestMethod.POST)
    public ModelAndView addTravelerDetails(@ModelAttribute("travelDetailsPersist") TravelDetails travelDetailsPersist, @ModelAttribute("travelDetails") TravelDetails travelDetails, ModelMap modelMap){
        System.out.println(travelDetailsPersist.getOrigin);
        System.out.println(travelDetailsPersist.getDestination);
        System.out.println(travelDetails.getTravelerName);
        System.out.println(travelDetails.getTravelerAge);
        return new ModelAndView("get_traveler_details");
    }  
}