Question

我一直试图找出如何填充Spring MVC中的下拉框。关于这个问题有一些主题，但我找到的没有一个帮助过我，所以我希望有人可以帮助我。

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@ModelAttribute方法来检索文档编号

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

但它给了我错误。有谁知道应该怎么做？

感谢您的时间

/ d

编辑我想我已经澄清，我希望有一个文件编号的下拉框，由documentService检索。

编辑2 以下是所请求的错误日志：

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";  
}

}

Answer 1

@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，我们用它来携带下拉标签和值项。它将具有label和value属性，以及相应的getter / setter。

LabelValue.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>

希望这会有所帮助..

Answer 2

不确定调用哪种Controller方法来显示documentNumberList的视图，但是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());

虽然从您的异常堆栈跟踪中您还错过了documentService字段上的@Autowired。

Answer 3

我今天已经解决了这个问题。这非常简单易懂。在Spring MVC 3.0控制器中只需放置此代码 -

 @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内可用，这意味着无论请求映射网址是什么，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将在“creditCardTypes”ModelAttribute中可用。多数民众赞成！

如何在Spring MVC中填充下拉框

3 个答案: