封装GridBagLayout的EasyGridLayout组件布局类和GridBagConstraints类字段解析

一、实用源程序，可以用于自己的类库中调用相应的setConstraints方法即可迅速地实现界面良好布局 ：
package ioutil;
import javax.swing.*;
import java.awt.*;
public class EasyGridLayout extends GridBagLayout{
 public void setConstraints(JLabel c, int row, int col,
                               int width, int height){
      finishSet(c, row, col, width, height,
                 0, 0,
                 GridBagConstraints.NONE,
                 GridBagConstraints.NORTHWEST);
   }
     
public void setConstraints (JButton c, int row, int col,
                               int width, int height){
      finishSet (c, row, col, width, height,
                 0,0,
                 GridBagConstraints.NONE,
                 GridBagConstraints.CENTER);
   }
   public void setConstraints (JTextField c, int row, int col,
                               int width, int height){
      finishSet (c, row, col, width, height,
                 100, 0,
                 GridBagConstraints.HORIZONTAL,
                 GridBagConstraints.NORTHWEST);
   }
    public void setConstraints (JScrollPane c, int row, int col,
                               int width, int height){
      finishSet (c, row, col, width, height,
                 100, 100,
                 GridBagConstraints.BOTH,
                 GridBagConstraints.NORTHWEST);
   }
public void setConstraints (JTextArea c, int row, int col,
                               int width, int height){
      finishSet (c, row, col, width, height,
                 100, 100,
                 GridBagConstraints.BOTH,
                 GridBagConstraints.NORTHWEST);
   }
 public void setConstraints (JList c, int row, int col,
                               int width, int height){
      finishSet (c, row, col, width, height,
                 100, 100,
                 GridBagConstraints.BOTH,
                 GridBagConstraints.NORTHWEST);
   }
public void setConstraints (JCheckBox c, int row, int col,
                               int width, int height){
     finishSet (c, row, col, width, height,
                0, 0,
                GridBagConstraints.HORIZONTAL,
                GridBagConstraints.NORTHWEST);
   }
public void setConstraints (JRadioButton c, int row, int col,
                               int width, int height){
     finishSet (c, row, col, width, height,
                0, 0,
                GridBagConstraints.HORIZONTAL,
                GridBagConstraints.NORTHWEST);
   }
 public void setConstraints (JPanel c, int row, int col,
                               int width, int height){
      finishSet (c, row, col, width, height,
                 100, 100,
                 GridBagConstraints.BOTH,
                 GridBagConstraints.NORTHWEST);
   }
private void finishSet (Component c, int y, int x, int w, int h,// gridx,gridwidth4个单位都是网格
                           int weightx, int weighty, // 分配额外空间比例给行列 ，以上三种都是如何将网格分配给组件。
                           int fill, int anchor){// 组件大于或小于网格时伸缩或放置位置。 在特定网格区域内设置伸缩，放置，内边距。
                          
      GridBagConstraints gbc = new GridBagConstraints();
     
      gbc.insets.bottom = 5; / /组件与放置它的grix、gridy之间的偏移，单位为px.
      gbc.insets.left = 5;
      gbc.insets.right = 5;
      gbc.insets.top = 5;
      gbc.insets.left = 5;
      gbc.insets.right = 5;
      gbc.insets.top = 5;
      
      gbc.weightx = weightx;
      gbc.weighty = weighty;
      
      gbc.fill = fill;
      gbc.anchor = anchor;
      
      gbc.gridx = x-1;
      gbc.gridy = y-1;
      
      gbc.gridwidth = w;
      gbc.gridheight = h;
      setConstraints(c, gbc);//
   }
}

二、 测试类代码， 为了了解上述的源程序所写：
package ioutil;
import javax.swing.*;
import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
public class GridBagLayoutInstance  extends JPanel{
    public GridBagLayoutInstance() {
     this.setLayout(new GridBagLayout());
        this.setOpaque(true);//the component should be opaque透明的。
        GridBagConstraints c = new GridBagConstraints();
        JButton b = new JButton ("Button One");
        c.gridx = 0 ;//控件左上角坐标
        c.gridy = 0;
        c.gridwidth = 2;//所占cell个数
        c.gridheight = 1;
        this.add(b,c);//button 1 added

        c.gridy++;
        b= new JButton("Button Two");
        this.add(b,c);

       c.gridx = 2;
        c.gridy = 0;
        c.gridwidth = 1;
        c.gridheight = 2;
        b = new JButton("Button Three");
        this.add(b,c);

        c.gridx = 3;
        c.gridy = 0;
        c.gridwidth = 1;
        c.gridheight = 2;
        //c.insets.top=10;
        //c.insets.left=10;
        //c.fill=GridBagConstraints.HORIZONTAL;
        //c.anchor=GridBagConstraints.ABOVE_BASELINE;
        b = new JButton("Button Fourth");
         this.add(b,c);
     
       c.gridx = 0 ;
        c.gridy = 2;
       c.gridwidth = 4;
        c.gridheight =1 ;
        this.add(new JTextField(35),c);
        }

        public static void main(String[] args) {
        JFrame f = new JFrame("GridBagLayout Instance ");
        JPanel p = new GridBagLayoutInstance();
        f.getContentPane().add(p);
        f.pack();
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        //f.setSize(300,400);
        f.setVisible(true);
  } }   
三、拓展学习GridBagConstraints类及测试类结果：
因为GridBagLayout提供的强大的功能，可以将组件布局在大小、个数不同的网格中，所以要借助一个聚合类GridBagConstriants类，下面关于GridBagConstriants类众多常量设置的解析：
测试原来界面：

 
first：如何将网格分配给组件 ：
1.gridx字段：组件的左上角坐标单位为单元格，初始为（0,0）坐标
  gbc.gridx=0;
  gbc.gridy=0;
   gbc.gridx = x-1;
      gbc.gridy = y-1;
2.gridwidth gridheight字段：组件在长宽覆盖的单元格的个数
   gbc.gridwidth = 2;
   gbc.gridheight = 1;    
3.weightx weighty,指定如何分布额外的水平、垂直空间给行列用于显示大组件 ，全部将额外行列空间分配为100,0时为不分配给行列，将额外的分配给行列之间或者在边距出。默认为0.
 gbc.weightx = weightx
  gbc.weighty = weighty;
将两个同时设置为0,100,30时对比:

 
sencond：在特定网格区域内设置伸缩，放置，内边距：
4.insets.left字段：组件与放置它的grix、gridy之间的偏移，单位为px但不用写出 .
gbc.insets.left=10; 
gbc.insets.right=10；
jbutton.insets.top
jbutton.insets.bottom
都设置为10时显示：

5.fill字段：指定组件如何伸缩填充包含它的网格区域。一般是指组件大于它的网格时。
gbc.fill=GridBagConstraints.NONE HORIZONTAL VERTICAL BOTH，也可以是用户传递进去的数值。
BOTH设置情形：

HORIZONTAL设置情形：

 6.anchor字段：它可以确定在显示区域中放置组件的位置， 当组件小于它的网格时。默认为absolute的CENTER.
(1)absolute 绝对值
gbc.anchor=Constraints.CENTER;
gbc.anchor=Constraints.NORTHWEST;
gbc.anchor=Constraints.NORTH;
EAST、SOUTHEAST、SOUTH、SOUTHWEST、WEST 和 NORTHWEST
NORTHWEST设置：

 (2)orientation relative基于方向的值
gbc.anchor=Constraints.PAGE_START;
gbc.anchor=Constraints.LINE_START;
gbc.anchor=Constraints.LINE_END;
PAGE_START, PAGE_END, LINE_START, LINE_END, FIRST_LINE_START, FIRST_LINE_END, LAST_LINE_START and LAST_LINE_END.
PAGE_START设置：

 LINE_START设置：

 
(3)baseline relvative 相对于基线的值
gbc.anchor=Constraints.BASELINE;
gbc.anchor=Constraints.ABOVE_BASELINE;
gbc.anchor=Constraints.BELOW_BASELINE_LEADING;
BASELINE设置：

 ABOVE_BASELINE设置：