11

我一直在尝试找出如何在 Spring MVC 中填充下拉框。关于这个主题有一些线程，但我发现它们都没有帮助我，所以我希望这里有人可以帮助我。

这是我的控制器：

@Controller
@RequestMapping("/document-revision") 
public class DocumentRevisionController {


@Autowired
private DocumentRevisionService documentRevisionService;
private DocumentService documentService;

@RequestMapping(value="/list", method=RequestMethod.GET) 
public String getDocumentRevisionList(Model model) {
    List<DocumentRevision> documentRevisions = documentRevisionService.retrieveAllDocumentRevisions();
    model.addAttribute("documentRevisions", documentRevisions);

    return "document-revision";
}

@RequestMapping(value="/add", method=RequestMethod.GET)
public String getDocumentRevision(Model model) {
    DocumentRevision documentRevision = new DocumentRevision();
    model.addAttribute("documentRevisionAttribute", documentRevision);
    return "new-documnent-revision";
}


@RequestMapping(value="/add", method=RequestMethod.POST)
public String postDocumentRevision(@ModelAttribute("documentRevisionAttribute") @Valid DocumentRevision documentRevision, BindingResult result) {

    if(result.hasErrors()){
        return "new-document-revision";
    }

    documentRevisionService.createDocumentRevision(documentRevision);
    return "redirect:/testapp/document-revision/list";  
}

}

这是jsp页面：

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form" %>

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
        <style>
        .error { color: red; }
        </style>
</head>
<body>

    <h1>Create New Document Revision</h1>

    <c:url var="saveUrl" value="/testapp/document-revision/add" />
    <form:form modelAttribute="documentRevisionAttribute" method="POST" action="${saveUrl}">
        <table>
            <tr>
                <td>DocumentNumber</td>
                <td><form:select path="document_number">
                    <form:option value="NONE" label="--- Select ---" />
                    <form:options items="${documentNumberList}" />
                    </form:select>
                </td>
                <td><form:errors path="document_number" cssClass="error" /></td>
            </tr>


            <tr>
                <td><form:label path="documentRState">Document R-State</form:label></td>
                <td><form:input path="documentRState"/></td>
                <td><form:errors path="documentRState" cssClass="error"/></td>
            </tr>

        </table>

        <input type="submit" value="Save" />
    </form:form>

</body>
</html>

我尝试添加一个检索文档编号的@ModelAttribute 方法，

        @ModelAttribute
    public List<Document> documentNumberList(){
        return documentService.retrieveAllDocumentNumbers();
    }

但它给了我错误。有没有人知道应该怎么做？

感谢您的时间

/D

编辑我想我会澄清我的愿望是为documentService检索的文档编号提供一个下拉框。

编辑 2这是所要求的错误日志：

java.lang.NullPointerException
testapp.controller.DocumentRevisionController.documentNumberList(DocumentRevisionController.java:33)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:601)
org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:212)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
org.springframework.web.method.annotation.ModelFactory.invokeModelAttributeMethods(ModelFactory.java:123)
org.springframework.web.method.annotation.ModelFactory.initModel(ModelFactory.java:97)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:614)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:900)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

解决方案我想我会添加完整的控制器代码，以防有其他人可以从中受益：

@Controller
@RequestMapping("/document-revision") 
public class DocumentRevisionController {


@Autowired
private DocumentRevisionService documentRevisionService;

@Autowired
    private DocumentService documentService;

@RequestMapping(value="/list", method=RequestMethod.GET) 
public String getDocumentRevisionList(Model model) {
    List<DocumentRevision> documentRevisions = documentRevisionService.retrieveAllDocumentRevisions();
    model.addAttribute("documentRevisions", documentRevisions);

    return "document-revision";
}

@RequestMapping(value="/add", method=RequestMethod.GET)
public String getDocumentRevision(Model model) {
    DocumentRevision documentRevision = new DocumentRevision();
    model.addAttribute("documentRevisionAttribute", documentRevision);
    model.addAttribute("documentNumberList", documentService.retrieveAllDocumentNumbers());

    return "new-documnent-revision";
}


@RequestMapping(value="/add", method=RequestMethod.POST)
public String postDocumentRevision(@ModelAttribute("documentRevisionAttribute") @Valid DocumentRevision documentRevision, BindingResult result) {

    if(result.hasErrors()){
        return "new-document-revision";
    }

    documentRevisionService.createDocumentRevision(documentRevision);
    return "redirect:/testapp/document-revision/list";  
}

}
4

3 回答 3

9 
@ModelAttribute("numberList")
public List<Document> documentNumberList(){
    List<LabelValue> selectItems = new ArrayList<LabelValue>();
    List<Document> docList = documentService.retrieveAllDocumentNumbers();
    for (Document doc : docList) {
     selectItems.add(new LabelValue(doc.id,doc.value));
}
    return selectItems;
}

FYI LabelValue 类是一个简单的 DTO，我们用来携带下拉标签和值项。它将具有标签和值属性，以及相应的 getter/setter。

标签值.java

 private String lable;
 private String value;

 //getters/setters

---- JSP -----

<tr>
    <td>DocumentNumber</td>
    <td><form:select id="docNo" path="document_number">
           <form:option value="NONE" label="--- Select ---" />
           <form:options items="${numberList}" itemValue="value" itemLabel="lable"/>
         </form:select>
    </td>
    <td><form:errors path="document_number" cssClass="error" /></td>
</tr>

希望这可以帮助..

于 2012-05-08T13:58:12.987 回答
8

不确定调用了什么控制器方法来显示您的视图documentNumberList，但您需要将该集合添加到传递给此视图的模型中：

model.addAttribute("documentNumberList", documentService.retrieveAllDocumentNumbers());

尽管从您的异常堆栈跟踪中您也错过了@Autowired ondocumentService字段。

于 2012-05-08T13:40:05.463 回答
8

我今天自己解决了这种问题。这非常简单易懂。在 Spring MVC 3.0 控制器中，只需放置以下代码 -

 @ModelAttribute("creditCardTypes")
 public Map<String,String> populateCreditCardTypes() {
        Map<String,String> creditCardTypes = new LinkedHashMap<String,String>();
        creditCardTypes.put("VS", "Visa");creditCardTypes.put("MC", "MasterCard");
        creditCardTypes.put("AE", "American Express");
        creditCardTypes.put("DS", "Discover");creditCardTypes.put("DC", "Diner's Club");                
        return creditCardTypes;
    }

现在“creditCardTypes”属性将在页面加载或页面提交范围中可用，这意味着无论请求映射 url 是什么，它都可用。

在 jsp 中，将此代码放在 - 信用卡类型中：

<form:select path="creditCardType">
    <option value="Select" label="Select a card type"></option>
    <form:options items="${creditCardTypes}" />
</form:select>

这里，path="creditCardType" 表示 Spring MVC 模型/命令对象中的属性，items="${creditCardTypes}" 表示所有填充的信用卡类型都将在 "creditCardTypes" ModelAttribute 中可用。就是这样 ！！！

于 2013-04-30T10:26:00.077 回答