12.6 复杂的布局管理器

1 网格组布局

import java.awt.EventQueue;

import javax.swing.JFrame;

/**
 * @version 1.35 2015-06-12
 * @author Cay Horstmann
 */
public class GridBagLayoutTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() ->           {
               JFrame frame = new FontFrame();
               frame.setTitle("GridBagLayoutTest");
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               frame.setVisible(true);
         });
   }
}

import java.awt.Font;
import java.awt.GridBagLayout;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JCheckBox;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextArea;

/**
 * A frame that uses a grid bag layout to arrange font selection components.
 */
public class FontFrame extends JFrame
{
   public static final int TEXT_ROWS = 10;
   public static final int TEXT_COLUMNS = 20;

   private JComboBox face;
   private JComboBox size;
   private JCheckBox bold;
   private JCheckBox italic;
   private JTextArea sample;

   public FontFrame()
   {
      GridBagLayout layout = new GridBagLayout();
      setLayout(layout);

      ActionListener listener = event -> updateSample();

      // construct components

      JLabel faceLabel = new JLabel("Face: ");

      face = new JComboBox<>(new String[] { "Serif", "SansSerif", "Monospaced",
            "Dialog", "DialogInput" });

      face.addActionListener(listener);

      JLabel sizeLabel = new JLabel("Size: ");

      size = new JComboBox<>(new Integer[] { 8, 10, 12, 15, 18, 24, 36, 48 });

      size.addActionListener(listener);

      bold = new JCheckBox("Bold");
      bold.addActionListener(listener);

      italic = new JCheckBox("Italic");
      italic.addActionListener(listener);

      sample = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
      sample.setText("The quick brown fox jumps over the lazy dog");
      sample.setEditable(false);
      sample.setLineWrap(true);
      sample.setBorder(BorderFactory.createEtchedBorder());

      // add components to grid, using GBC convenience class

      add(faceLabel, new GBC(0, 0).setAnchor(GBC.EAST));
      add(face, new GBC(1, 0).setFill(GBC.HORIZONTAL).setWeight(100, 0)
            .setInsets(1));
      add(sizeLabel, new GBC(0, 1).setAnchor(GBC.EAST));
      add(size, new GBC(1, 1).setFill(GBC.HORIZONTAL).setWeight(100, 0)
            .setInsets(1));
      add(bold, new GBC(0, 2, 2, 1).setAnchor(GBC.CENTER).setWeight(100, 100));
      add(italic, new GBC(0, 3, 2, 1).setAnchor(GBC.CENTER).setWeight(100, 100));
      add(sample, new GBC(2, 0, 1, 4).setFill(GBC.BOTH).setWeight(100, 100));
      pack();
      updateSample();
   }

   public void updateSample()
   {
      String fontFace = (String) face.getSelectedItem();
      int fontStyle = (bold.isSelected() ? Font.BOLD : 0)
            + (italic.isSelected() ? Font.ITALIC : 0);
      int fontSize = size.getItemAt(size.getSelectedIndex());
      Font font = new Font(fontFace, fontStyle, fontSize);
      sample.setFont(font);
      sample.repaint();
   }
}

import java.awt.*;

/**
 * This class simplifies the use of the GridBagConstraints class.
 * @version 1.01 2004-05-06
 * @author Cay Horstmann
 */
public class GBC extends GridBagConstraints
{
   /**
    * Constructs a GBC with a given gridx and gridy position and all other grid
    * bag constraint values set to the default.
    * @param gridx the gridx position
    * @param gridy the gridy position
    */
   public GBC(int gridx, int gridy)
   {
      this.gridx = gridx;
      this.gridy = gridy;
   }

   /**
    * Constructs a GBC with given gridx, gridy, gridwidth, gridheight and all
    * other grid bag constraint values set to the default.
    * @param gridx the gridx position
    * @param gridy the gridy position
    * @param gridwidth the cell span in x-direction
    * @param gridheight the cell span in y-direction
    */
   public GBC(int gridx, int gridy, int gridwidth, int gridheight)
   {
      this.gridx = gridx;
      this.gridy = gridy;
      this.gridwidth = gridwidth;
      this.gridheight = gridheight;
   }

   /**
    * Sets the anchor.
    * @param anchor the anchor value
    * @return this object for further modification
    */
   public GBC setAnchor(int anchor)
   {
      this.anchor = anchor;
      return this;
   }

   /**
    * Sets the fill direction.
    * @param fill the fill direction
    * @return this object for further modification
    */
   public GBC setFill(int fill)
   {
      this.fill = fill;
      return this;
   }

   /**
    * Sets the cell weights.
    * @param weightx the cell weight in x-direction
    * @param weighty the cell weight in y-direction
    * @return this object for further modification
    */
   public GBC setWeight(double weightx, double weighty)
   {
      this.weightx = weightx;
      this.weighty = weighty;
      return this;
   }

   /**
    * Sets the insets of this cell.
    * @param distance the spacing to use in all directions
    * @return this object for further modification
    */
   public GBC setInsets(int distance)
   {
      this.insets = new Insets(distance, distance, distance, distance);
      return this;
   }

   /**
    * Sets the insets of this cell.
    * @param top the spacing to use on top
    * @param left the spacing to use to the left
    * @param bottom the spacing to use on the bottom
    * @param right the spacing to use to the right
    * @return this object for further modification
    */
   public GBC setInsets(int top, int left, int bottom, int right)
   {
      this.insets = new Insets(top, left, bottom, right);
      return this;
   }

   /**
    * Sets the internal padding
    * @param ipadx the internal padding in x-direction
    * @param ipady the internal padding in y-direction
    * @return this object for further modification
    */
   public GBC setIpad(int ipadx, int ipady)
   {
      this.ipadx = ipadx;
      this.ipady = ipady;
      return this;
   }
}

2 组布局

import java.awt.EventQueue;

import javax.swing.JFrame;

/**
 * @version 1.01 2015-06-12
 * @author Cay Horstmann
 */
public class GroupLayoutTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new FontFrame();
         frame.setTitle("GroupLayoutTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

import java.awt.Font;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.GroupLayout;
import javax.swing.JCheckBox;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.LayoutStyle;
import javax.swing.SwingConstants;

/**
 * A frame that uses a group layout to arrange font selection components.
 */
public class FontFrame extends JFrame
{
   public static final int TEXT_ROWS = 10;
   public static final int TEXT_COLUMNS = 20;

   private JComboBox face;
   private JComboBox size;
   private JCheckBox bold;
   private JCheckBox italic;
   private JScrollPane pane;
   private JTextArea sample;

   public FontFrame()
   {
      ActionListener listener = event -> updateSample(); 

      // construct components

      JLabel faceLabel = new JLabel("Face: ");

      face = new JComboBox<>(new String[] { "Serif", "SansSerif", "Monospaced", "Dialog",
            "DialogInput" });

      face.addActionListener(listener);

      JLabel sizeLabel = new JLabel("Size: ");

      size = new JComboBox<>(new Integer[] { 8, 10, 12, 15, 18, 24, 36, 48 });

      size.addActionListener(listener);

      bold = new JCheckBox("Bold");
      bold.addActionListener(listener);

      italic = new JCheckBox("Italic");
      italic.addActionListener(listener);

      sample = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
      sample.setText("The quick brown fox jumps over the lazy dog");
      sample.setEditable(false);
      sample.setLineWrap(true);
      sample.setBorder(BorderFactory.createEtchedBorder());

      pane = new JScrollPane(sample);

      GroupLayout layout = new GroupLayout(getContentPane());
      setLayout(layout);
      layout.setHorizontalGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(
                  layout.createSequentialGroup().addContainerGap().addGroup(
                        layout.createParallelGroup(GroupLayout.Alignment.LEADING).addGroup(
                              GroupLayout.Alignment.TRAILING,
                              layout.createSequentialGroup().addGroup(
                                    layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
                                          .addComponent(faceLabel).addComponent(sizeLabel))
                                    .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                    .addGroup(
                                          layout.createParallelGroup(
                                                GroupLayout.Alignment.LEADING, false)
                                                .addComponent(size).addComponent(face)))
                              .addComponent(italic).addComponent(bold)).addPreferredGap(
                        LayoutStyle.ComponentPlacement.RELATED).addComponent(pane)
                        .addContainerGap()));

      layout.linkSize(SwingConstants.HORIZONTAL, new java.awt.Component[] { face, size });

      layout.setVerticalGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(
                  layout.createSequentialGroup().addContainerGap().addGroup(
                        layout.createParallelGroup(GroupLayout.Alignment.LEADING).addComponent(
                              pane, GroupLayout.Alignment.TRAILING).addGroup(
                              layout.createSequentialGroup().addGroup(
                                    layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                          .addComponent(face).addComponent(faceLabel))
                                    .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                    .addGroup(
                                          layout.createParallelGroup(
                                                GroupLayout.Alignment.BASELINE).addComponent(size)
                                                .addComponent(sizeLabel)).addPreferredGap(
                                          LayoutStyle.ComponentPlacement.RELATED).addComponent(
                                          italic, GroupLayout.DEFAULT_SIZE,
                                          GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                    .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(bold, GroupLayout.DEFAULT_SIZE,
                                          GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
                        .addContainerGap()));
      pack();
   }

   public void updateSample()
   {
      String fontFace = (String) face.getSelectedItem();
      int fontStyle = (bold.isSelected() ? Font.BOLD : 0)
            + (italic.isSelected() ? Font.ITALIC : 0);
      int fontSize = size.getItemAt(size.getSelectedIndex());
      Font font = new Font(fontFace, fontStyle, fontSize);
      sample.setFont(font);
      sample.repaint();
   }
}

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3 不使用布局

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4 自定义布局管理

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.33 2015-06-12
 * @author Cay Horstmann
 */
public class CircleLayoutTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new CircleLayoutFrame();
         frame.setTitle("CircleLayoutTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

import javax.swing.*;

/**
 * A frame that shows buttons arranged along a circle.
 */
public class CircleLayoutFrame extends JFrame
{
   public CircleLayoutFrame()
   {
      setLayout(new CircleLayout());
      add(new JButton("Yellow"));
      add(new JButton("Blue"));
      add(new JButton("Red"));
      add(new JButton("Green"));
      add(new JButton("Orange"));
      add(new JButton("Fuchsia"));
      add(new JButton("Indigo"));
      pack();
   }
}

import java.awt.*;

/**
 * A layout manager that lays out components along a circle.
 */
public class CircleLayout implements LayoutManager
{
   private int minWidth = 0;
   private int minHeight = 0;
   private int preferredWidth = 0;
   private int preferredHeight = 0;
   private boolean sizesSet = false;
   private int maxComponentWidth = 0;
   private int maxComponentHeight = 0;

   public void addLayoutComponent(String name, Component comp)
   {
   }

   public void removeLayoutComponent(Component comp)
   {
   }

   public void setSizes(Container parent)
   {
      if (sizesSet) return;
      int n = parent.getComponentCount();

      preferredWidth = 0;
      preferredHeight = 0;
      minWidth = 0;
      minHeight = 0;
      maxComponentWidth = 0;
      maxComponentHeight = 0;

      // compute the maximum component widths and heights
      // and set the preferred size to the sum of the component sizes.
      for (int i = 0; i < n; i++)
      {
         Component c = parent.getComponent(i);
         if (c.isVisible())
         {
            Dimension d = c.getPreferredSize();
            maxComponentWidth = Math.max(maxComponentWidth, d.width);
            maxComponentHeight = Math.max(maxComponentHeight, d.height);
            preferredWidth += d.width;
            preferredHeight += d.height;
         }
      }
      minWidth = preferredWidth / 2;
      minHeight = preferredHeight / 2;
      sizesSet = true;
   }

   public Dimension preferredLayoutSize(Container parent)
   {
      setSizes(parent);
      Insets insets = parent.getInsets();
      int width = preferredWidth + insets.left + insets.right;
      int height = preferredHeight + insets.top + insets.bottom;
      return new Dimension(width, height);
   }

   public Dimension minimumLayoutSize(Container parent)
   {
      setSizes(parent);
      Insets insets = parent.getInsets();
      int width = minWidth + insets.left + insets.right;
      int height = minHeight + insets.top + insets.bottom;
      return new Dimension(width, height);
   }

   public void layoutContainer(Container parent)
   {
      setSizes(parent);

      // compute center of the circle

      Insets insets = parent.getInsets();
      int containerWidth = parent.getSize().width - insets.left - insets.right;
      int containerHeight = parent.getSize().height - insets.top - insets.bottom;

      int xcenter = insets.left + containerWidth / 2;
      int ycenter = insets.top + containerHeight / 2;

      // compute radius of the circle

      int xradius = (containerWidth - maxComponentWidth) / 2;
      int yradius = (containerHeight - maxComponentHeight) / 2;
      int radius = Math.min(xradius, yradius);

      // lay out components along the circle

      int n = parent.getComponentCount();
      for (int i = 0; i < n; i++)
      {
         Component c = parent.getComponent(i);
         if (c.isVisible())
         {
            double angle = 2 * Math.PI * i / n;

            // center point of component
            int x = xcenter + (int) (Math.cos(angle) * radius);
            int y = ycenter + (int) (Math.sin(angle) * radius);

            // move component so that its center is (x, y)
            // and its size is its preferred size
            Dimension d = c.getPreferredSize();
            c.setBounds(x - d.width / 2, y - d.height / 2, d.width, d.height);
         }
      }
   }
}

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5 遍历顺序