richfaces动态显示列

<rich:dataTable value="#{logbookReport.rows}" var="row">
<rich:columnGroup>
<rich:column>
<h:outputText value="#{row.timestamp}" />
</rich:column>
<rich:columns value="#{logbookReport.columns}" index="index">
<h:outputText value="#{row.values[index]}" />
</rich:columns>
<rich:column>
<h:outputText value="#{row.comment}" />
</rich:column>
</rich:columnGroup>
</rich:dataTable>

public class LogbookReport {

private List rows;
private List columns = Arrays.asList(new String [] {"","",""});;
private List totals;
}