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AWT GridBagLayout

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介紹

GridBagLayout 類組件排列在一個水平和垂直的方式。

類的聲明

以下是聲明的java.awt.GridBagLayout類：

public class GridBagLayout
   extends Object
      implements LayoutManager2, Serializable

字段域

下麵是java.awt.BorderLayout類的字段：

  • double[] columnWeights -- 此字段存放列權重的重寫。

  • int[] columnWidths -- 此字段中擁有覆蓋列的最小寬度。

  • protected Hashtable comptable -- 這個哈希表維護組件和它的網格包約束之間的關聯。

  • protected GridBagConstraints defaultConstraints -- 此字段保存網格包約束實例包含默認值，因此如果某個組件冇有與它相關聯的網格包約束，那麼該組件將被分配副本defaultConstraints

  • protected java.awt.GridBagLayoutInfo layoutInfo -- 此字段持有網格包布局信息。

  • protected static int MAXGRIDSIZE -- 最大數量的的網格位置（水平和垂直），可以鋪設是由網格包布局。

  • protected static int MINSIZE -- 可安排最小的網格由網格包布局。

  • protected static int PREFERREDSIZE -- 首選的網格大小，可以布局網格袋布局。

  • int[] rowHeights -- 此字段持有覆蓋到該行的最低高度。

  • double[] rowWeights -- 此字段持有行權的重寫。

類的構造函數

S.N. 構造函數與說明
1 GridBagLayout()
Creates a grid bag layout manager.

類方法

S.N. Method & Description
1 void addLayoutComponent(Component comp, Object constraints) 
Adds the specified component to the layout, using the specified constraints object.
2 void addLayoutComponent(String name, Component comp) 
Adds the specified component with the specified name to the layout.
3 protected void adjustForGravity(GridBagConstraints constraints, Rectangle r) 
Adjusts the x, y, width, and height fields to the correct values depending on the constraint geometry and pads.
4 protected void AdjustForGravity(GridBagConstraints constraints, Rectangle r) 
This method is obsolete and supplied for backwards compatability only; new code should call adjustForGravity instead.
5 protected void arrangeGrid(Container parent) 
Lays out the grid.
6 protected void ArrangeGrid(Container parent) 
This method is obsolete and supplied for backwards compatability only; new code should call arrangeGrid instead.
7 GridBagConstraints getConstraints(Component comp) 
Gets the constraints for the specified component.
8 float getLayoutAlignmentX(Container parent) 
Returns the alignment along the x axis.
9 float getLayoutAlignmentY(Container parent) 
Returns the alignment along the y axis.
10 int[][] getLayoutDimensions() 
Determines column widths and row heights for the layout grid.
11 protected java.awt.GridBagLayoutInfo getLayoutInfo(Container parent, int sizeflag) 
Fills in an instance of GridBagLayoutInfo for the current set of managed children.
12 protected java.awt.GridBagLayoutInfo GetLayoutInfo(Container parent, int sizeflag) 
This method is obsolete and supplied for backwards compatability only; new code should call getLayoutInfo instead.
13 Point getLayoutOrigin() 
Determines the origin of the layout area, in the graphics coordinate space of the target container.
14 double[][] getLayoutWeights() 
Determines the weights of the layout grid's columns and rows.
15 protected Dimension getMinSize(Container parent, java.awt.GridBagLayoutInfo info) 
Figures out the minimum size of the master based on the information from getLayoutInfo().
16 protected Dimension GetMinSize(Container parent, java.awt.GridBagLayoutInfo info) 
This method is obsolete and supplied for backwards compatability only; new code should call getMinSize instead.
17 void invalidateLayout(Container target) 
Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.
18 void layoutContainer(Container parent) 
Lays out the specified container using this grid bag layout.
19 Point location(int x, int y) 
Determines which cell in the layout grid contains the point specified by (x, y).
20 protected GridBagConstraints lookupConstraints(Component comp) 
Retrieves the constraints for the specified component.
21 Dimension maximumLayoutSize(Container target) 
Returns the maximum dimensions for this layout given the components in the specified target container.
22 Dimension minimumLayoutSize(Container parent) 
Determines the minimum size of the parent container using this grid bag layout.
23 Dimension preferredLayoutSize(Container parent) 
Determines the preferred size of the parent container using this grid bag layout.
24 void removeLayoutComponent(Component comp) 
Removes the specified component from this layout.
25 void setConstraints(Component comp, GridBagConstraints constraints) 
Sets the constraints for the specified component in this layout.
26 String toString() 
Returns a string representation of this grid bag layout's values.

繼承的方法

這個類繼承的方法從以下類：

  • java.lang.Object

GridBagLayout 實例

選擇使用任何編輯器創建以下java程序 D:/ > AWT > com > yiibai > gui >

AwtLayoutDemo 
package com.yiibai.gui;

import java.awt.*;
import java.awt.event.*;

public class AwtLayoutDemo {
   private Frame mainFrame;
   private Label headerLabel;
   private Label statusLabel;
   private Panel controlPanel;
   private Label msglabel;

   public AwtLayoutDemo(){
      prepareGUI();
   }

   public static void main(String[] args){
      AwtLayoutDemo  awtLayoutDemo = new AwtLayoutDemo();  
      awtLayoutDemo.showGridBagLayoutDemo();       
   }
      
   private void prepareGUI(){
      mainFrame = new Frame("Java AWT Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new Label();
      headerLabel.setAlignment(Label.CENTER);
      statusLabel = new Label();        
      statusLabel.setAlignment(Label.CENTER);
      statusLabel.setSize(350,100);

      msglabel = new Label();
      msglabel.setAlignment(Label.CENTER);
      msglabel.setText("Welcome to TutorialsPoint AWT Tutorial.");

      controlPanel = new Panel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }

   private void showGridBagLayoutDemo(){
      headerLabel.setText("Layout in action: GridBagLayout");      

      Panel panel = new Panel();
      panel.setBackground(Color.darkGray);
      panel.setSize(300,300);
      GridBagLayout layout = new GridBagLayout();

      panel.setLayout(layout);        
      GridBagConstraints gbc = new GridBagConstraints();

      gbc.fill = GridBagConstraints.HORIZONTAL;
      gbc.gridx = 0;
      gbc.gridy = 0;
      panel.add(new Button("Button 1"),gbc);

      gbc.gridx = 1;
      gbc.gridy = 0;
      panel.add(new Button("Button 2"),gbc); 

      gbc.fill = GridBagConstraints.HORIZONTAL;
      gbc.ipady = 20;   
      gbc.gridx = 0;
      gbc.gridy = 1;
      panel.add(new Button("Button 3"),gbc); 

      gbc.gridx = 1;
      gbc.gridy = 1;       
      panel.add(new Button("Button 4"),gbc);  

      gbc.gridx = 0;
      gbc.gridy = 2;      
      gbc.fill = GridBagConstraints.HORIZONTAL;
      gbc.gridwidth = 2;
      panel.add(new Button("Button 5"),gbc);  

      controlPanel.add(panel);

      mainFrame.setVisible(true);  
   }
}

編譯程序，使用命令提示符。進入到D:/> AWT，然後鍵入以下命令。

D:AWT>javac comyiibaiguiAwtlayoutDemo.java

如果冇有錯誤出現，這意味著編譯成功。使用下麵的命令來運行程序。

D:AWT>java com.yiibai.gui.AwtlayoutDemo

驗證下麵的輸出

AWT GridBagLayout
 


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