Faces ActionEvent.getSource始终为null [英] Faces ActionEvent.getSource always null

查看：119 发布时间：2017/4/3 20:56:36 jsf datatable

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问题描述

我有我的Faces ActionEvent返回一个源的问题，但是对！= null的检查返回false。
疯狂的事实是，在调试模式下，我收到一个填充的ActionEvent变量。

我已将代码分解为重要的部分

Bean：

  public class HibernateUserHandling 
 {
 public void deleteUser（ActionEvent ev）
 {
 if（ev.getSource（）！= null&& ev.getSource（）instanceof HtmlDataTable）{
 HtmlDataTable objHtmlDataTable =（HtmlDataTable）ev.getSource （）; 
 setRowOfUserToDelete（objHtmlDataTable.getRowIndex（））; 
 setPersonsCopy（HibernateDataOutput.persons）; 
 setUserToDelete（getPersonsCopy（）[getRowOfUserToDelete（）]）; 
 setUserIdToDelete（（Integer）getUserToDelete（）。getUserId（））; 
} 
}

查看：

 < html> 
< body> 
< ui：composition template =./ generalTemplate.xhtml
 xmlns =http://www.w3.org/1999/xhtml
 xmlns：h =http： //java.sun.com/jsf/html
 xmlns：f =http://java.sun.com/jsf/core
 xmlns：ui =http：// java。 sun.com/jsf/facelets\"> 
< ui：define name =content> 
< h：outputStylesheet library =cssname =cssHibernate.css/> 
< h：form id =main> 
< h：dataTable value =＃{hibernateDataOutput.persons}var =list
 styleClass =order-table
 headerClass =order-table-header
 rowClasses =order-table-odd-row，order-table-even-row> 
< h：column> 
< f：facet name =header> Delete< / f：facet> 
< h：commandButton id =deleteactionListener =＃{hibernateUserHandling ['deleteUser']}image =delete.jpg/> 
< / h：column> 
< / h：dataTable> 
< / h：form> 
< / ui：define> 
< / ui：composition> 
< / body> 
< / html>

我没有收到错误，它只是跳过If块，因为ev.getSource （）！= null。

提前感谢

TLS

解决方案

ActionEvent 不能为 null 。这将是使用JSF实现的一个巨大的bug。但是， ActionEvent＃getSource（）可以永远不会是这个 HtmlDataTable 的一个实例特殊情况。这是一个 HtmlCommandButton 的实例，因为您从< h：commandButton> 中调用它。所以整个如果块将永远不会通过。

这就是说，这是一个非常笨拙的方法来获取当前个人删除。也许你专注于完全过时的基于JSF 1.x的书籍/教程/资源。有更好的方法来获取当前的 Person ，导致这一点：

 < h：dataTable value =＃{hibernateDataOutput.persons}var =person> 
< h：column> 
< h：commandButton action =＃{hibernateUserHandling.deleteUser（person）}image =delete.jpg/> 
< / h：column> 
< / h：dataTable>

与

  public void deleteUser（User user）{
 someUserService.delete（user）; 
}

另请参见：

如何将参数传递给datatable内的commandLink？

I have the problem that my Faces ActionEvent returns a source, but the check on != null returns false. The crazy fact is, that in debug mode I get a filled ActionEvent variable.

I have broken down the code to the important sections

Bean:

public class HibernateUserHandling 
{
    public void deleteUser(ActionEvent ev)
    {
        if (ev.getSource() != null && ev.getSource() instanceof HtmlDataTable) {
            HtmlDataTable objHtmlDataTable = (HtmlDataTable) ev.getSource();
            setRowOfUserToDelete(objHtmlDataTable.getRowIndex());
            setPersonsCopy(HibernateDataOutput.persons);
            setUserToDelete(getPersonsCopy()[getRowOfUserToDelete()]);
            setUserIdToDelete((Integer) getUserToDelete().getUserId());
        }
}

View:

<html>
    <body>
        <ui:composition template="./generalTemplate.xhtml"
        xmlns="http://www.w3.org/1999/xhtml"
        xmlns:h="http://java.sun.com/jsf/html"
        xmlns:f="http://java.sun.com/jsf/core"
        xmlns:ui="http://java.sun.com/jsf/facelets">
        <ui:define name="content">
            <h:outputStylesheet library="css" name="cssHibernate.css" />
                <h:form id="main">
                    <h:dataTable value="#{hibernateDataOutput.persons}" var="list"
                                styleClass="order-table"
                                headerClass="order-table-header"
                                rowClasses="order-table-odd-row,order-table-even-row">
                        <h:column>
                            <f:facet name="header">Delete</f:facet>
                            <h:commandButton id="delete" actionListener="#{hibernateUserHandling['deleteUser']}" image="delete.jpg"/>
                        </h:column>
                    </h:dataTable>
                </h:form>
            </ui:define>
        </ui:composition>
    </body>
</html>

I don't get an error, it just skips the If block because of the "ev.getSource() != null".

Thanks in advance,

TLS

解决方案

The ActionEvent can't be null. It would be a huge bug in the JSF implementation used. However, the ActionEvent#getSource() can never be an instance of HtmlDataTable in this particular case. It's an instance of HtmlCommandButton since you're calling it from a <h:commandButton>. So the whole if block will never pass.

That said, this is a pretty clumsy way to get the current Person to delete. Perhaps you focused too much on completely outdated JSF 1.x based books/tutorials/resources. There are much better ways to get the current Person, leading with this:

<h:dataTable value="#{hibernateDataOutput.persons}" var="person">
    <h:column>
        <h:commandButton action="#{hibernateUserHandling.deleteUser(person)}" image="delete.jpg" />
    </h:column>
</h:dataTable>

with

public void deleteUser(User user) {
    someUserService.delete(user);
}

Faces ActionEvent.getSource始终为null [英] Faces ActionEvent.getSource always null

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Faces ActionEvent.getSource始终为null [英] Faces ActionEvent.getSource always null

问题描述

另请参见：

See also:

相关文章

其他数据库最新文章

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