java - Vaadin - 如果我使用 AbsoluteLayout，则不会显示表数据

Question

目前，我在使用 Vaadin Table 时遇到了一个非常奇怪的问题。如果我在表中使用 AbsoluteLayout 数据不会显示，但如果我使用即 Horizo​​ntalLayout，数据会完美显示。这有效:

import com.vaadin.annotations.AutoGenerated;
import com.vaadin.ui.CustomComponent;
import com.vaadin.ui.HorizontalLayout;
import com.vaadin.ui.Table;

public class MyComposite extends CustomComponent {


    @AutoGenerated
    private HorizontalLayout mainLayout;
    @AutoGenerated
    private Table table;


    public MyComposite() {
        buildMainLayout();
        setCompositionRoot(mainLayout);
        // TODO add user code here

        table.addContainerProperty("First Name", String.class, null);
        table.addContainerProperty("Last Name", String.class, null);
        table.addContainerProperty("Year", Integer.class, null);

        table.addItem(new Object[] { "Nicolaus", "Copernicus",
                new Integer(1473) }, new Integer(1));
        table.addItem(new Object[] { "Tycho", "Brahe", new Integer(1546) },
                new Integer(2));

    }

    @AutoGenerated
    private HorizontalLayout buildMainLayout() {
        // common part: create layout
        mainLayout = new HorizontalLayout();
        mainLayout.setStyleName("blue");
        mainLayout.setImmediate(false);
        mainLayout.setWidth("100%");
        mainLayout.setHeight("100%");
        mainLayout.setMargin(false);

        // top-level component properties
        setWidth("100.0%");
        setHeight("100.0%");

        // table
        table = new Table();
        table.setImmediate(false);
        table.setWidth("100.0%");
        table.setHeight("100.0%");
        mainLayout.addComponent(table);

        return mainLayout;
    }

}

但这不是:

import com.vaadin.annotations.AutoGenerated;
import com.vaadin.ui.AbsoluteLayout;
import com.vaadin.ui.CustomComponent;
import com.vaadin.ui.Table;

public class MyComposite extends CustomComponent {


    @AutoGenerated
    private AbsoluteLayout mainLayout;
    @AutoGenerated
    private Table table;
    public MyComposite() {
        buildMainLayout();
        setCompositionRoot(mainLayout);
        // TODO add user code here

        table.addContainerProperty("First Name", String.class, null);
        table.addContainerProperty("Last Name", String.class, null);
        table.addContainerProperty("Year", Integer.class, null);

        table.addItem(new Object[] { "Nicolaus", "Copernicus",
                new Integer(1473) }, new Integer(1));
        table.addItem(new Object[] { "Tycho", "Brahe", new Integer(1546) },
                new Integer(2));

    }

    @AutoGenerated
    private AbsoluteLayout buildMainLayout() {
        // common part: create layout
        mainLayout = new AbsoluteLayout();
        mainLayout.setStyleName("blue");
        mainLayout.setImmediate(false);
        mainLayout.setWidth("100%");
        mainLayout.setHeight("100%");

        // top-level component properties
        setWidth("100.0%");
        setHeight("100.0%");

        // table
        table = new Table();
        table.setImmediate(false);
        table.setWidth("100.0%");
        table.setHeight("100.0%");
        mainLayout.addComponent(table);

        return mainLayout;
    }

}

两种情况下都会显示列的名称。有人能告诉我为什么会这样吗？提前致谢。

Answer 1

我能够重现您的问题。似乎 Vaadin 的家伙在这里描述了原因: Vaadin book

引用:

A layout that contains components with percentual size must have a defined size!

If a layout has undefined size and a contained component has, say, 100% size, the component will try to fill the space given by the layout, while the layout will shrink to fit the space taken by the component, which is a paradox. This requirement holds for height and width separately. The debug mode allows detecting such invalid cases; see Section 11.3.5, “Inspecting Component Hierarchy”

对于 AbsoluteLayout，到目前为止我发现的唯一解决方法是将表格尺寸设置为一些固定值。