【发布时间】：2012-01-02 01:11:51
【问题描述】：
如标题所述，我一直在尝试设置一种带有水平滚动的垂直流布局。布局中的组件将是 JLabels。让我画个图：
+-------------------------+ <--- window
|Label1 Label4 Label7|
|Label2 Label5 Label8| <--- labels
|Label3 Label6 Label9|
|<===============>========| <--- scrollbar
+-------------------------+
同一个窗口，垂直展开
+--------------------------+ <--- window
|Label1 Label5 Label9 |
|Label2 Label6 Label10| <--- labels
|Label3 Label7 Label11|
|Label4 Label8 Label12|
|<===================>=====| <--- scrollbar
+--------------------------+
因此，标签将填充可用的垂直空间，然后创建一个新列。一旦可用的水平空间用完，就会出现一个水平滚动条。
垂直滚动条通常不应该出现；但是，如果窗口的垂直高度非常小，最好有一个垂直滚动条。
非常感谢任何帮助。我是 Java 新手，所以任何额外的解释都会很棒。谢谢！
编辑：
根据以下回复，我现在正在处理： http://tips4java.wordpress.com/2008/11/06/wrap-layout/ 和 http://code.google.com/p/verticalflowlayout/
我有 WrapLayout 像这样扩展 VerticalFlowLayout：
package LogicSim;
import java.awt.*;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
/**
* FlowLayout subclass that fully supports wrapping of components.
*/
public class VerticalWrapLayout extends VerticalFlowLayout
{
private Dimension preferredLayoutSize;
/**
* Constructs a new <code>WrapLayout</code> with a left
* alignment and a default 5-unit horizontal and vertical gap.
*/
public VerticalWrapLayout()
{
super();
}
/**
* Constructs a new <code>FlowLayout</code> with the specified
* alignment and a default 5-unit horizontal and vertical gap.
* The value of the alignment argument must be one of
* <code>WrapLayout</code>, <code>WrapLayout</code>,
* or <code>WrapLayout</code>.
* @param align the alignment value
*/
public VerticalWrapLayout(int align)
{
super(align);
}
/**
* Creates a new flow layout manager with the indicated alignment
* and the indicated horizontal and vertical gaps.
* <p>
* The value of the alignment argument must be one of
* <code>WrapLayout</code>, <code>WrapLayout</code>,
* or <code>WrapLayout</code>.
* @param align the alignment value
* @param hgap the horizontal gap between components
* @param vgap the vertical gap between components
*/
public VerticalWrapLayout(int align, int hgap, int vgap)
{
super(align, hgap, vgap);
}
/**
* Returns the preferred dimensions for this layout given the
* <i>visible</i> components in the specified target container.
* @param target the component which needs to be laid out
* @return the preferred dimensions to lay out the
* subcomponents of the specified container
*/
@Override
public Dimension preferredLayoutSize(Container target)
{
return layoutSize(target, true);
}
/**
* Returns the minimum dimensions needed to layout the <i>visible</i>
* components contained in the specified target container.
* @param target the component which needs to be laid out
* @return the minimum dimensions to lay out the
* subcomponents of the specified container
*/
@Override
public Dimension minimumLayoutSize(Container target)
{
Dimension minimum = layoutSize(target, false);
minimum.width -= (getHgap() + 1);
return minimum;
}
/**
* Returns the minimum or preferred dimension needed to layout the target
* container.
*
* @param target target to get layout size for
* @param preferred should preferred size be calculated
* @return the dimension to layout the target container
*/
private Dimension layoutSize(Container target, boolean preferred)
{
synchronized (target.getTreeLock())
{
// Each row must fit with the width allocated to the containter.
// When the container width = 0, the preferred width of the container
// has not yet been calculated so lets ask for the maximum.
int targetWidth = target.getSize().width;
if (targetWidth == 0)
targetWidth = Integer.MAX_VALUE;
int hgap = getHgap();
int vgap = getVgap();
Insets insets = target.getInsets();
int horizontalInsetsAndGap = insets.left + insets.right + (hgap * 2);
int maxWidth = targetWidth - horizontalInsetsAndGap;
// Fit components into the allowed width
Dimension dim = new Dimension(0, 0);
int rowWidth = 0;
int rowHeight = 0;
int nmembers = target.getComponentCount();
for (int i = 0; i < nmembers; i++)
{
Component m = target.getComponent(i);
if (m.isVisible())
{
Dimension d = preferred ? m.getPreferredSize() : m.getMinimumSize();
// Can't add the component to current row. Start a new row.
if (rowWidth + d.width > maxWidth)
{
addRow(dim, rowWidth, rowHeight);
rowWidth = 0;
rowHeight = 0;
}
// Add a horizontal gap for all components after the first
if (rowWidth != 0)
{
rowWidth += hgap;
}
rowWidth += d.width;
rowHeight = Math.max(rowHeight, d.height);
}
}
addRow(dim, rowWidth, rowHeight);
dim.width += horizontalInsetsAndGap;
dim.height += insets.top + insets.bottom + vgap * 2;
// When using a scroll pane or the DecoratedLookAndFeel we need to
// make sure the preferred size is less than the size of the
// target containter so shrinking the container size works
// correctly. Removing the horizontal gap is an easy way to do this.
Container scrollPane = SwingUtilities.getAncestorOfClass(JScrollPane.class, target);
if (scrollPane != null)
{
dim.width -= (hgap + 1);
}
return dim;
}
}
/*
* A new row has been completed. Use the dimensions of this row
* to update the preferred size for the container.
*
* @param dim update the width and height when appropriate
* @param rowWidth the width of the row to add
* @param rowHeight the height of the row to add
*/
private void addRow(Dimension dim, int rowWidth, int rowHeight)
{
dim.width = Math.max(dim.width, rowWidth);
if (dim.height > 0)
{
dim.height += getVgap();
}
dim.height += rowHeight;
}
}
这是我的框架设置：
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 300);
frame.setVisible(true);
JPanel panel = new JPanel();
panel.setLayout( new VerticalWrapLayout(0) );
JScrollPane pane = new JScrollPane(panel);
frame.add( pane, BorderLayout.CENTER );
for (int i=0; i < 80; i++ ) {
panel.add( new JLabel( "Label" + i ) );
}
现在，这会按照我所追求的方式在垂直列中设置标签，但它仍然会创建垂直滚动条。在修改 VerticalWrapLayout 类时，我很不安。另外，我真的不明白 JScrollPane 如何与这些类交互。有关如何进行的任何建议？
已解决！请参阅下面的答案以及我的答案。
【问题讨论】：
标签： java swing jframe jpanel layout-manager