如何从ManagedBean获取primefaces数据表列的顺序和宽度

你错了什么:

不要p:column在里面筑巢p:columns

DataTable.getColumns不会返回您期望的内容:

public List<UIColumn> getColumns() {
    if(columns == null) {
        columns = new ArrayList<UIColumn>();
        FacesContext context = getFacesContext();
        char separator = UINamingContainer.getSeparatorChar(context);

        for(UIComponent child : this.getChildren()) {
            if(child instanceof Column) {
                columns.add((UIColumn) child);
            }
            else if(child instanceof Columns) {
                Columns uiColumns = (Columns) child;
                String uiColumnsClientId = uiColumns.getClientId(context);

                for(int i=0; i < uiColumns.getRowCount(); i++) {
                    DynamicColumn dynaColumn = new DynamicColumn(i, uiColumns);
                    dynaColumn.setColumnKey(uiColumnsClientId + separator + i);
                    columns.add(dynaColumn);
                }
            }
        }
    }

    return columns;
}

这将返回一个合成仿真:仅columnKey按列,并且如您所述,返回正确的列数.

一般来说,p:columns是一个组件,当你从控制器层访问它时,你必须引用它的DECLARATION(单个组件)而不是它的REPRESENTATION(多个列)

因为你支持p:columns你,#{datatableBean.table}你应该已经拥有了你想要从DataTable组件获得的所有信息,这是以逆向工程方式提供的.

更新

哦,现在我意识到你想做什么.你必须使用事件监听器.

来自PF展示:

<p:dataTable var="car" value="#{tableBean.carsSmall}" widgetVar="cars" draggableRows="true">  

    <p:ajax event="colReorder" listener="#{tableBean.onColReorder}" update=":some:component" />  

    <p:ajax event="colResize" listener="#{tableBean.onColResize}" update=":some:component"/>    

    <!-- columns here -->  
</p:dataTable> 

在支持bean中监听这些事件并保持这些信息可以解决您的问题

更新2

哇,这一点都不简单.

由于Primefaces错误的动态列调整大小(至少我的尝试)和不完整的列重新排序事件实现,这是出来的:

<h:form id="form">
    <h:panelGroup id="model">
        <ui:repeat var="column2" value="#{testBean.columnList2}">
            <div>#{column2.title} - #{column2.width}</div>
        </ui:repeat>
    </h:panelGroup>

    <p:dataTable var="elem" value="#{testBean.elementList}" resizableColumns="true" draggableColumns="true">
        <p:ajax event="colReorder" listener="#{testBean.onColumnReorder}" update=":form:model" />  
        <p:ajax event="colResize" listener="#{testBean.onColumnResize}" update=":form:model"/>  

        <c:forEach var="column" items="#{testBean.columnList}">
            <p:column headerText="#{column.title}" rendered="#{column.visible}" >
                <f:attribute name="myCol" value="#{column}"/>
                <span>#{elem[column.property]}</span>
            </p:column>
        </c:forEach>
    </p:dataTable>
</h:form>

而这个豆子:

@ManagedBean
@ViewScoped
public class TestBean implements Serializable
{
    private static final long serialVersionUID = 1L;

    private List<MyColumn> columnList;
    private List<MyColumn> columnList2;
    private List<MyElement> elementList;

    public class MyColumn
    {
        private String title;
        private String property;
        private boolean visible = true;
        private boolean resizable = true;
        private int width = 100;

        public MyColumn(String title, String property, boolean visible, boolean resizable, int width)
        {
            super();
            this.title = title;
            this.property = property;
            this.visible = visible;
            this.resizable = resizable;
            this.width = width;
        }

        // getters and setters
    }

    public class MyElement
    {
        private String code;
        private String name;
        private String type;

        public MyElement(String code, String name, String type)
        {
            super();
            this.code = code;
            this.name = name;
            this.type = type;
        }

        // getters and setters
    }

    @PostConstruct
    public void init()
    {
        columnList = new ArrayList<>();
        columnList.add(new MyColumn("element code", "code", true, true, 100));
        columnList.add(new MyColumn("element name", "name", true, true, 100));
        columnList.add(new MyColumn("element type", "type", true, true, 100));

        columnList2 = new ArrayList<>(columnList);

        elementList = new ArrayList<>();
        elementList.add(new MyElement("001", "foo", "normal"));
        elementList.add(new MyElement("002", "bar", "strange"));
        elementList.add(new MyElement("003", "xyz", "normal"));
        elementList.add(new MyElement("004", "abc", "nothing"));
    }

    public void onColumnResize(ColumnResizeEvent event)
    {
        UIColumn column = event.getColumn();
        int width = event.getWidth();

        UIComponent colComponent = (UIComponent) column;
        MyColumn myCol = (MyColumn) colComponent.getAttributes().get("myCol");

        myCol.setWidth(width);
    }

    public void onColumnReorder(AjaxBehaviorEvent event)
    {
        DataTable table = (DataTable) event.getSource();

        columnList2.clear();

        for(UIColumn column : table.getColumns())
        {
            UIComponent colComponent = (UIComponent) column;

            MyColumn myCol = (MyColumn) colComponent.getAttributes().get("myCol");
            columnList2.add(myCol);
        }
    }

    // getters and setters

}

更新的代码,您可以在中找到有序列columnList2.现在也显示在表格中.现在你可以columnList2用来存储oreder和width到db.