java – 寻找GridBagLayout组件创建的一般方法

1)首先,我创建了2个枚举,它们是锚点和填充GridBagConstraints字段的包装器.我更喜欢enums与int的类型检查,它还允许我编写更简洁的代码(稍后你会看到).是的,我仍然使用较旧的“方向”值为Anchor.我永远不会习惯于PAGE_START之类的首选值.用你喜欢的任何东西.

Anchor.java：

package gbl;

import java.awt.*;

/**
 * Convenience enum that aliases out all possible values for the
 * GridBagConstraints anchor property.
 */
public enum Anchor
{
  NORTH(GridBagConstraints.NORTH),SOUTH(GridBagConstraints.SOUTH),EAST(GridBagConstraints.EAST),WEST(GridBagConstraints.WEST),NORTHEAST(GridBagConstraints.NORTHEAST),NORTHWEST(GridBagConstraints.NORTHWEST),SOUTHEAST(GridBagConstraints.SOUTHEAST),SOUTHWEST(GridBagConstraints.SOUTHWEST),CENTER(GridBagConstraints.CENTER);

  private int constraint;

  private Anchor(int gbConstraint)
  {
    constraint = gbConstraint;
  }

  public int getConstraint()
  {
    return constraint;
  }
}

Fill.java：

package gbl;

import java.awt.*;

/**
 * Convenience enum that aliases out all possible values for the
 * GridBagConstraints fill property.
 */
public enum Fill
{
  NONE(GridBagConstraints.NONE),HORIZONTAL(GridBagConstraints.HORIZONTAL),VERTICAL(GridBagConstraints.VERTICAL),BOTH(GridBagConstraints.BOTH);

  private int constraint;

  private Fill(int gbConstraint)
  {
    constraint = gbConstraint;
  }

  public int getConstraint()
  {
    return constraint;
  }
}

2)然后,我创建了一个GridBagConstraints的子类,它允许我在需要时“链接”属性,同时利用常见的默认值：

GBConstraints.java：

package gbl;

import java.awt.*;

/**
 * Convenience class to simplify the creation of a GridBagConstraints object.
 */
public class GBConstraints extends GridBagConstraints
{
  public GBConstraints(int gridX,int gridY)
  {
    super();

    this.gridx = gridX;
    this.gridy = gridY;

    this.gridwidth = 1;
    this.gridheight = 1;
    this.weightx = 0;
    this.weighty = 0;
    this.anchor = NORTHWEST;              // old default was CENTER
    this.fill = NONE;
    this.insets = new Insets(1,2);    // old default was (0,0)
    this.ipadx = 1;                       // old default was 0
    this.ipady = 1;                       // old default was 0
  }

  public GBConstraints anchor(Anchor anchor)
  {
    this.anchor = anchor.getConstraint();
    return this;
  }

  public GBConstraints fill(Fill fill)
  {
    this.fill = fill.getConstraint();

    /*
     * As a convenience,set the weights appropriately since these values are
     * almost always used in tandem with the given Fill. The caller can always
     * call the weight(...) method later if these defaults aren't desired. 
     */
    switch (fill)
    {
      case HORIZONTAL:
        this.weightx = 1;
        this.weighty = 0;
        break;
      case VERTICAL:
        this.weightx = 0;
        this.weighty = 1;
        break;
      case BOTH:
        this.weightx = 1;
        this.weighty = 1;
        break;
      default:
        this.weightx = 0;
        this.weighty = 0;
        break;
    }

    return this;
  }

  public GBConstraints insets(int length)
  {
    return insets(length,length,length);
  }

  public GBConstraints insets(int top,int left,int bottom,int right)
  {
    this.insets = new Insets(top,left,bottom,right);
    return this;
  }

  public GBConstraints ipad(int ipadX,int ipadY)
  {
    this.ipadx = ipadX;
    this.ipady = ipadY;
    return this;
  }

  public GBConstraints span(int gridWidth,int gridHeight)
  {
    this.gridwidth = gridWidth;
    this.gridheight = gridHeight;
    return this;
  }

  public GBConstraints spanX(int gridWidth)
  {
    this.gridwidth = gridWidth;
    return this;
  }

  public GBConstraints spanY(int gridHeight)
  {
    this.gridheight = gridHeight;
    return this;
  }

  public GBConstraints weight(double weightX,double weightY)
  {
    this.weightx = weightX;
    this.weighty = weightY;
    return this;
  }

  public GBConstraints weightX(double weightX)
  {
    this.weightx = weightX;
    return this;
  }

  public GBConstraints weightY(double weightY)
  {
    this.weighty = weightY;
    return this;
  }
}

3)将所有内容放在一起,这是一个演示如何使用上述类的演示.这大大简化了使用GridBagLayout,恕我直言.旁注：我通常远离静态导入,但在这种情况下我喜欢它.

演示：

package gbl;

import static gbl.Anchor.*;
import static gbl.Fill.*;

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

public class GridBagDemo implements Runnable
{
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new GridBagDemo());
  }

  public void run()
  {
    JLabel lblFirst  = new JLabel("First Name");
    JLabel lblLast   = new JLabel("Last Name");
    JLabel lblStreet = new JLabel("Street");
    JLabel lblCity   = new JLabel("City");
    JLabel lblState  = new JLabel("State");
    JLabel lblZip    = new JLabel("ZIP");
    JLabel lblNotes  = new JLabel("Notes");

    JTextField txfFirst  = new JTextField(15);
    JTextField txfLast   = new JTextField(20);
    JTextField txfStreet = new JTextField(40);
    JTextField txfCity   = new JTextField(15);
    JTextField txfState  = new JTextField(5);
    JTextField txfZip    = new JTextField(10);

    JTextArea txaNotes = new JTextArea(5,50);
    JScrollPane scrNotes = new JScrollPane(txaNotes);
    scrNotes.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

    Component spacer1 = Box.createHorizontalStrut(5);
    Component spacer2 = Box.createHorizontalStrut(5);

    JPanel panel = new JPanel(new GridBagLayout());
    panel.add(spacer1,new GBConstraints(0,0));
    panel.add(lblFirst,1));
    panel.add(txfFirst,new GBConstraints(1,1));
    panel.add(lblLast,new GBConstraints(2,1));
    panel.add(txfLast,new GBConstraints(3,1).spanX(3).fill(HORIZONTAL));
    panel.add(lblStreet,2));
    panel.add(txfStreet,2).spanX(5).fill(HORIZONTAL));
    panel.add(lblCity,3));
    panel.add(txfCity,3));
    panel.add(lblState,3).anchor(EAST));
    panel.add(txfState,3));
    panel.add(lblZip,new GBConstraints(4,3));
    panel.add(txfZip,new GBConstraints(5,3).fill(HORIZONTAL));
    panel.add(lblNotes,4));
    panel.add(scrNotes,4).spanX(5).fill(BOTH));
    panel.add(spacer2,5));

    JFrame frame = new JFrame("Grid Bag Demo");
    frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new JScrollPane(panel),BorderLayout.CENTER);
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}

同样,这只是您在网上找到的众多方式之一.希望这可以帮助.