java swing 垂直流布局管理器实现

最近写一个java UI，需要用到垂直流布局管理器，要求该管理器能够实现内部组件的宽度自适应。看了swing提供的5个布局管理器，尝试的实现效果都不理想，看来只能自己搞一个了，好在网上已有实现，其测试效果如下图：

图一 垂直流布局管理器实现效果

具体代码如下：

清单一：

import java.awt.Component;import java.awt.Container;import java.awt.Dimension;import java.awt.FlowLayout;import java.awt.Insets;import javax.swing.JButton;import javax.swing.JFrame;/** * VerticalFlowLayout is similar to FlowLayout except it lays out components * vertically. Extends FlowLayout because it mimics much of the behavior of the * FlowLayout class, except vertically. An additional feature is that you can * specify a fill to edge flag, which causes the VerticalFlowLayout manager to * resize all components to expand to the column width Warning: This causes * problems when the main panel has less space that it needs and it seems to * prohibit multi-column output. Additionally there is a vertical fill flag, * which fills the last component to the remaining height of the container. */public class VFlowLayout extends FlowLayout{/** *  */private static final long serialVersionUID = 1L;/** * Specify alignment top. */public static final int TOP = 0;/** * Specify a middle alignment. */public static final int MIDDLE = 1;/** * Specify the alignment to be bottom. */public static final int BOTTOM = 2;int hgap;int vgap;boolean hfill;boolean vfill;public static void main(String[] args){System.out.println("Just for test ...");JFrame frame = new JFrame();frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);frame.setBounds(0, 0, 600, 600);frame.setLayout(new VFlowLayout());int i = 0;frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.add(new JButton(String.valueOf(i++)));frame.setVisible(true);}/** * Construct a new VerticalFlowLayout with a middle alignment, and the fill * to edge flag set. */public VFlowLayout(){this(TOP, 5, 5, true, false);}/** * Construct a new VerticalFlowLayout with a middle alignment. *  * @param hfill *            the fill to edge flag * @param vfill *            the vertical fill in pixels. */public VFlowLayout(boolean hfill, boolean vfill){this(TOP, 5, 5, hfill, vfill);}/** * Construct a new VerticalFlowLayout with a middle alignment. *  * @param align *            the alignment value */public VFlowLayout(int align){this(align, 5, 5, true, false);}/** * Construct a new VerticalFlowLayout. *  * @param align *            the alignment value * @param hfill *            the horizontalfill in pixels. * @param vfill *            the vertical fill in pixels. */public VFlowLayout(int align, boolean hfill, boolean vfill){this(align, 5, 5, hfill, vfill);}/** * Construct a new VerticalFlowLayout. *  * @param align *            the alignment value * @param hgap *            the horizontal gap variable * @param vgap *            the vertical gap variable * @param hfill *            the fill to edge flag * @param vfill *            true if the panel should vertically fill. */public VFlowLayout(int align, int hgap, int vgap, boolean hfill, boolean vfill){setAlignment(align);this.hgap = hgap;this.vgap = vgap;this.hfill = hfill;this.vfill = vfill;}/** * Returns the preferred dimensions given the components in the target * container. *  * @param target *            the component to lay out */public Dimension preferredLayoutSize(Container target){Dimension tarsiz = new Dimension(0, 0);for (int i = 0; i < target.getComponentCount(); i++){Component m = target.getComponent(i);if (m.isVisible()){Dimension d = m.getPreferredSize();tarsiz.width = Math.max(tarsiz.width, d.width);if (i > 0){tarsiz.height += hgap;}tarsiz.height += d.height;}}Insets insets = target.getInsets();tarsiz.width += insets.left + insets.right + hgap * 2;tarsiz.height += insets.top + insets.bottom + vgap * 2;return tarsiz;}/** * Returns the minimum size needed to layout the target container. *  * @param target *            the component to lay out. * @return the minimum layout dimension. */public Dimension minimumLayoutSize(Container target){Dimension tarsiz = new Dimension(0, 0);for (int i = 0; i < target.getComponentCount(); i++){Component m = target.getComponent(i);if (m.isVisible()){Dimension d = m.getMinimumSize();tarsiz.width = Math.max(tarsiz.width, d.width);if (i > 0) {tarsiz.height += vgap;}tarsiz.height += d.height;}}Insets insets = target.getInsets();tarsiz.width += insets.left + insets.right + hgap * 2;tarsiz.height += insets.top + insets.bottom + vgap * 2;return tarsiz;}/** * Set true to fill vertically. *  * @param vfill *            true to fill vertically. */public void setVerticalFill(boolean vfill){this.vfill = vfill;}/** * Returns true if the layout vertically fills. *  * @return true if vertically fills the layout using the specified. */public boolean getVerticalFill(){return vfill;}/** * Set to true to enable horizontally fill. *  * @param hfill *            true to fill horizontally. */public void setHorizontalFill(boolean hfill){this.hfill = hfill;}/** * Returns true if the layout horizontally fills. *  * @return true if horizontally fills. */public boolean getHorizontalFill(){return hfill;}/** * places the components defined by first to last within the target * container using the bounds box defined. *  * @param target *            the container. * @param x *            the x coordinate of the area. * @param y *            the y coordinate of the area. * @param width *            the width of the area. * @param height *            the height of the area. * @param first *            the first component of the container to place. * @param last *            the last component of the container to place. */private void placethem(Container target, int x, int y, int width, int height, int first, int last){int align = getAlignment();if (align == MIDDLE){y += height / 2;}if (align == BOTTOM){y += height;}for (int i = first; i < last; i++){Component m = target.getComponent(i);Dimension md = m.getSize();if (m.isVisible()){int px = x + (width - md.width) / 2;m.setLocation(px, y);y += vgap + md.height;}}}/** * Lays out the container. *  * @param target *            the container to lay out. */public void layoutContainer(Container target){Insets insets = target.getInsets();int maxheight = target.getSize().height- (insets.top + insets.bottom + vgap * 2);int maxwidth = target.getSize().width - (insets.left + insets.right + hgap * 2);int numcomp = target.getComponentCount();int x = insets.left + hgap, y = 0;int colw = 0, start = 0;for (int i = 0; i < numcomp; i++){Component m = target.getComponent(i);if (m.isVisible()) {Dimension d = m.getPreferredSize();// fit last component to remaining heightif ((this.vfill) && (i == (numcomp - 1))) {d.height = Math.max((maxheight - y), m.getPreferredSize().height);}// fit component size to container widthif (this.hfill){m.setSize(maxwidth, d.height);d.width = maxwidth;} else{m.setSize(d.width, d.height);}if (y + d.height > maxheight){placethem(target, x, insets.top + vgap, colw, maxheight - y, start, i);y = d.height;x += hgap + colw;colw = d.width;start = i;} else{if (y > 0){y += vgap;}y += d.height;colw = Math.max(colw, d.width);}}}placethem(target, x, insets.top + vgap, colw, maxheight - y, start,numcomp);}}

文章转自：http://blog.csdn.net/dancen/article/details/7581971