Question

我正在尝试将默认值设置为h：selectOneMenu。但是，它没有用。

这是我的代码

的index.xhtml

<h:body>
        <h:form id="test">
        <h:selectOneMenu value="#{selectMenuBean.selectedItem}"
                         title="select version"
                         onchange="submit()"
                         disabled="false" id="combo">

            <f:selectItems value="#{selectMenuBean.selectItems}" />
        </h:selectOneMenu>

        </h:form>
    </h:body>

BackingBean

private String selectedItem;
private List selectItems;
private int version=3;

public List getSelectItems() {

    List<Version> selectedItems = ExportDao.getVersionsList();
    System.out.println("List size: "+selectedItems.size());
    selectItems = new ArrayList();

    for (Version v1 : selectedItems) {
        String DATE_FORMAT = "yyyy-MM-dd HH:mm";
        //Create object of SimpleDateFormat and pass the desired date format.
        SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
        selectItems.add(new SelectItem(v1.getVersion(), "V" + v1.getVersion() + "/" + sdf.format(v1.getDate())));
        if(version = v1.getVersion()) // I have to check the version and set the matching version as selected.
        selectedItem = "V" + v1.getVersion() + "/" + sdf.format(v1.getDate());

    }
    return selectItems;
}

Answer 1

您使用商品标签而不是商品值设置selectedItem。

替换

selectedItem = "V" + v1.getVersion() + "/" + sdf.format(v1.getDate());

通过

selectedItem = v1.getVersion();

Answer 2

一些可能的解决方案：

1）将selectItems的类型设置为SelectItem[]，而不是类型为List。

或2）尝试设置selectItems的var，itemValue和itemLabel属性，如下所示，并将实际的Version对象放入列表中。

或我最喜欢的，3）创建一个知道如何将Version对象转换为String的VersionConverter。如果您的Version对象持久存储在数据库中并且具有Id，则下面的示例。在构造之后，您的selectedItem和List selectItems应该具有typ Version（和List），而不是String。 JSF将自行处理转换。

@FacesConverter(forClass=Version.class)
public class VersionConverter implements Converter{

    public VersionConverter() {
    }

    @Override
    public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
        if (value == null || value.length() == 0) {
            return null;
        }
        try {
            // Get an EJB that can fetch the Version from a DB. Alternativly, do whatever you need to get your object from a string.
            InitialContext ic = new InitialContext();

            MyDao myDao = (MyDao)ic.lookup(String.format("java:global/%s/MyBean", (String)ic.lookup("java:module/ModuleName")));
            return myDao.findEntity(Version.class, getKey(value));
        } catch (NamingException e) {
            return null;
        }
    }

    Long getKey(String value) {
        Long key;
        key = Long.valueOf(value);
        return key;
    }

    String getStringKey(Long value) {
        StringBuilder sb = new StringBuilder();
        sb.append(value);
        return sb.toString();
    }

    @Override
    public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
        if (object == null) {
            return null;
        }
        if (object instanceof Version) {
            Version e = (Version) object;
            return getStringKey(e.getId());
        }
        else
            throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + Version.class.getName());
    }
}

如何将默认值设置为<h：selectonemenu> </h：selectonemenu>

2 个答案: