Question

我基本上有以下jsp来检索弹簧模型广告列表$ {myAdverts}附带的广告对象。

我希望当点击其中一个时，将一个帖子请求提交回我的控制器，但是有一个广告对象的实例。这有可能吗？

这是我的JSP代码：

<xc:forEach var="advertisement" items="${myAdverts}" varStatus="stats">
    <li>

    <a class="furtherinfo-link" onclick="javascript:submitJoin(${stats.count})" >${advertisement.getName()}</a>
    </li>
</xc:forEach>
<form:form id="myform" method="POST" action="form_submit.html" commandName="myForm" name="MyForm">
 <form:input id="advertisementObj" path="advertisementObj" type="hidden"/>
 </form:form>

这是我尝试使用javascript来回复发送帖子，其灵感来自Spring MVC和javascript中自动填充列表的处理：

javascript代码

 <script src="js/webmenu_nav.js"></script>

<script type="text/javascript">
      function submitJoin(position){
        $('#advertisementObj').val("myAdverts["+position+"]");

        document.MyForm.submit();
      }

</script>

该代码的当前行为是我总是在我的Controller对象的post方法中得到一个空的advertObj。

控制器对象非常简单，但在这里它是代码的一部分：

@Controller
public class MyController {

@RequestMapping(value="/show_advertisements.html",method = RequestMethod.GET)
public ModelAndView showAdv(@RequestParam(value="response", required=false) String incomingResponse) {

    Map<String, Object> model = new HashMap<String, Object>();
    model.put("response", incomingResponse);

    List<AdvertisementRecord> adverts = methodThatReturnsList();
    model.put("myAdverts", adverts);

    MyForm jform = new MyForm();
    model.put("myForm", jform);

    return new ModelAndView("show_advertisements", model) ;
}

@RequestMapping(value = "/form_submit.html", method = RequestMethod.POST)
public ModelAndView formSubmit(MyForm myForm,  BindingResult result, Map model){


    if(null != myForm.getAdvertisement())
        return showPage("adver " + myForm.getAdvertisement().getId());
    else
        return showPage("null advertisement on join");


}

 }

解决方案!!

解决方案代码的片段

JSP代码：

<xc:forEach var="advertisement" items="${myAdverts}" varStatus="stats">
    <li>
    <a class="furtherinfo-link" onclick="javascript:submitForm(${stats.count})" >${advertisement.getName()}</a>
    </li>
</xc:forEach>
<form:form method="POST" id="theForm" action="form_submit.html" modelAttribute="myAdverts" name="MyForm">
</form:form>

的javascript：

<script src="js/webmenu_nav.js"></script>

    <script type="text/javascript">
          function submitForm(position){
           $('#theForm').attr("action","form_submit.html?position="+position);

            document.MyForm.submit();
          }

    </script>

</head>

控制器：

 @Controller
 @SessionAttributes("myAdverts")
public class MyController {

@RequestMapping(value="/show_advertisements.html",method = RequestMethod.GET)
public ModelAndView showAdv(@RequestParam(value="response", required=false) String incomingResponse) {

    Map<String, Object> model = new HashMap<String, Object>();
    model.put("response", incomingResponse);

    List<AdvertisementRecord> adverts = methodThatReturnsList();
    model.put("myAdverts", adverts);

    //MyForm jform = new MyForm();
    //model.put("myForm", jform);

    return new ModelAndView("show_advertisements", model) ;
}

@RequestMapping(value = "/form_submit.html", method = RequestMethod.POST)
public ModelAndView formSubmit(@RequestParam("position") final int position, @ModelAttribute("adverts") @Valid List<AdvertisementRecord> adverts,  BindingResult result, Map model){


    if(null != adverts && null != adverts.get(position))
        return showPage("adver " + adverts.get(position).getId());
    else
        return showPage("null advertisement ");


}

 }

请注意上面的代码，重要的是让请求参数首先出现在签名中，因为我正在调用“form_submit.html？position =”+ position“

Answer 1

您放入模型的对象默认只存在当前请求。这意味着您的myAdverts列表在第二个请求（即POST请求）中不再存在。但是，您可以使用@SessionAttribute注释告诉spring mvc在http-session中存储对象，以便您可以在进一步的请求中访问它们。

您的控制器可能如下所示：

@Controller
@SessionAttributes("myAdverts")
public class MyController {
    @RequestMapping(value="...", method=RequestMethod.GET)
    public void get(ModelMap model){
        List myAdverts = // get your list of adverts.
        model.put("myAdverts", myAdverts)
    }

    @RequestMapping(value="...", method=RequestMethod.POST)
    public void post(@RequestParam("position") final int position, @ModelAttribute("myAdverts") List myAdverts,SessionStatus sessionStatus){
        myAdverts.get(position);
        // ...

        // tell spring to remove myAdverts from session
        sessionStatus.setComplete();
    }
}

有关@SessionAttribute的更多信息，请查看here。

Answer 2

如果广告具有某种唯一ID并存储在DAO中（或者有另一种从id获取广告的方式），您可以实现一个转换器，该转换器将接受String参数并将其转换回广告

public class StringToAdvertisementConverter implements Converter<String, Advertisement> {

    private AdvertisementRepository advertisementRepository

    @Autowired
    public setAdvertisementRepository(AdvertisementRepository repository){
        this.advertisementRepositort = repository;
    }

    @Override
    public Advertisement convert(String id) { 

         return advertisementRepository.lookup(id);
    }

}

在转换服务中注册转换器

<mvc:annotation-driven conversion-service="conversionService"/>

<bean id="conversionService"
      class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
    <property name="converters">
        <set>
            <bean class="my.StringToAdvertisementConverter"/>
        </set>
    </property>

您的控制器将能够接受广告类作为@RequestParam的参数和类似的注释：

    @RequestMapping(method = RequestMethod.POST, value = "/SomeMapping")
    public String handleSomething(@RequestParam(required = false) Advertisement advert,
        ModelMap model) {}

作为替代方案，您可以使用PropertyEditors获得相同的结果，a good question on topic包含许多指向Spring文档的链接。

是否可以将弹簧模型对象作为弹簧形式的值？

2 个答案: