Java 如何在 JSF 数据表中获取选定的行索引？
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How to get selected row index in JSF datatable?
提问by TCM
I have a databale on index.xhtml
我在 index.xhtml 上有一个数据库
<h:dataTable style="border: solid 2px black;"
value="#{IndexBean.bookList}" var="item"
binding="#{IndexBean.datatableBooks}">
<h:column>
<h:commandButton value="Edit" actionListener="#{IndexBean.editBook}">
<f:param name="index" value="#{IndexBean.datatableBooks.rowIndex}"/>
</h:commandButton>
</h:column>
</h:dataTable>
My bean:
我的豆子：
@ManagedBean(name="IndexBean")
@ViewScoped
public class IndexBean implements Serializable {
private HtmlDataTable datatableBooks;
public HtmlDataTable getDatatableBooks() {
return datatableBooks;
}
public void setDatatableBooks(HtmlDataTable datatableBooks) {
this.datatableBooks = datatableBooks;
}
public void editBook() throws IOException{
int index = Integer.parseInt(FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("index").toString());
System.out.println(index);
}
}
My problem is that I always get the same index in server log even though I click the different edit buttons. Imagine that there is one collection which is supplied to the datatable. I have not shown that in bean.
我的问题是，即使我单击了不同的编辑按钮，我总是在服务器日志中获得相同的索引。想象一下，有一个提供给数据表的集合。我没有在 bean 中显示它。
If I change scope from ViewScope to RequestScope it works fine. What can be the problem with @ViewScoped? Thanks in advance :)
如果我将范围从 ViewScope 更改为 RequestScope，它可以正常工作。可能有什么问题@ViewScoped？提前致谢 ：）
EDIT:
编辑：
<h:column>
<h:commandButton value="Edit" actionListener="#{IndexBean.editBook}" />
</h:column>
public void editBook(ActionEvent ev) throws IOException{
if (ev.getSource() != null && ev.getSource() instanceof HtmlDataTable) {
HtmlDataTable objHtmlDataTable = (HtmlDataTable) ev.getSource();
System.out.println(objHtmlDataTable.getRowIndex());
}
}
采纳答案by BalusC
You've already bound the <h:dataTable>component to the bean. All you need to do is:
您已经将<h:dataTable>组件绑定到 bean。您需要做的就是：
public void editBook() throws IOException{
int index = datatableBooks.getRowIndex(); // Actually not interesting info.
Book book = (Book) datatableBooks.getRowData(); // This is what you want.
}
The <f:param>is also not needed here. For more hints also see this article.
在<f:param>也这里不需要。有关更多提示，请参阅这篇文章。
Update: I can reproduce your problem. This is likely a bug with @ViewScoped. When the bean is set to @RequestScoped, it works as expected. Also when you remove the component binding and obtain the component from the viewroot yourself, it works as expected. I've filed issue 1658about this.
更新：我可以重现您的问题。这很可能是@ViewScoped. 当 bean 设置为 时@RequestScoped，它会按预期工作。此外，当您删除组件绑定并自己从 viewroot 获取组件时，它会按预期工作。我已经提交了关于这个的issue 1658。
回答by Romain Linsolas
What you can do is to use the [getRowData()][1]method on the Java bean to directly get the object located on the line that hosts the button on which the user clicked.
您可以做的是使用[getRowData()][1]Java bean 上的方法直接获取位于承载用户单击的按钮的行上的对象。
An example of code:
代码示例：
public void editBook(ActionEvent evt) {
// We get the table object
HtmlDataTable table = getParentDatatable((UIComponent) evt.getSource());
// We get the object on the selected line.
Object o = table.getRowData();
// Eventually, if you need the index of the line, simply do:
int index = table.getRowIndex();
// ...
}
// Method to get the HtmlDataTable.
private HtmlDataTable getParentDatatable(UIComponent compo) {
if (compo == null) {
return null;
}
if (compo instanceof HtmlDataTable) {
return (HtmlDataTable) compo;
}
return getParentDataTable(compo.getParent());
}
Edit编辑
The JSF code now looks like:
JSF 代码现在看起来像：
<h:commandButton value="Edit" actionListener="#{IndexBean.editBook}"/>
In addition, do not forget to change the signature of editBook()method, by setting a javax.faces.event.ActionEventargument.
此外，不要忘记editBook()通过设置javax.faces.event.ActionEvent参数来更改方法的签名。
回答by amanas
If you use EL 2.2, for example with Tomcat7 you can try
如果您使用 EL 2.2，例如使用 Tomcat7，您可以尝试
<h:commandLink action="#{IndexBean.editBook(item)}" immediate="true">
I hope to help
我希望有所帮助
