Java图形界面设计

一、总述

Java的图形用户界面由各种组件（component）构成，它们主要位于java.awt包与javax.swing包中。Swing与AWT最大的不同是，Swing在实现时，不包含任何本地代码(native)，是一种“轻量级(lightweight)”的组件

Swing具有状态的组件。

二、容器

1.顶层容器：

JFrame、JApplet、JDialog 和 JWindow

2.JFrame创建的一个程序

2.1代码

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

public class JFrameDemo{
public static void main(String args[]){
JFrame frame = new JFrame("JFrameDemo");
JButton button = new JButton("Press Me");

//first way to do that
// frame.getContentPane().add(button,BorderLayout.CENTER);

//another way to set the Pane
JPanel contentPane = new JPanel();
contentPane.setLayout(new BorderLayout());
contentPane.add(button,BorderLayout.CENTER);
frame.setContentPane(contentPane);

//frame.pack();
frame.setVisible(true);
}
}

2.2执行结果

3.面板（JPanel）

可以相互嵌套，不能独立存在，只能添加到其他窗口内部。

3.1代码

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

public class FrameWithPanel{
public static void main(String args[]){
JFrame frame = new JFrame("Frame with Panel");
Container contentPane = frame.getContentPane();
contentPane.setBackground(Color.CYAN);

JPanel panel = new JPanel();
panel.setBackground(Color.yellow);

JButton button = new JButton("Press me");
panel.add(button);
//add JButton instance to JPanel

//add JPanel instance to JFrame's south
contentPane.add(panel,BorderLayout.SOUTH);
frame.setSize(300,200);
frame.setVisible(true);
}
}

3.2执行结果

三、布局

1.总述

组件的布局（包括位置与大小）通常由Layout Manager负责安排。Java平台提供了多种布局管理器，以下对其部分，进行说明。

2.FlowLayout Layout Manager

2.1FlowLayout 的三种构造方法

public FlowLayout()
public FlowLayout(int align)
public FlowLayout(int align,int hgap,int vgap)

构造方法中，提供了一个对齐方式的可选项align，取值有三种形式：FlowLayout.LEFT、 FlowLayout.CENTER 、FlowLayout.RIGHT。hgap和vgap可以设定组件的水平间距和垂直距离。

2.2参考代码

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

public class FlowLayoutDemo{
private JFrame frame;
private JButton btn1,btn2,btn3;

public static void main(String args[]){
FlowLayoutDemo that = new FlowLayoutDemo();
that.go();
}
public void go(){
frame = new JFrame("Flow Layout");
Container contentPane = frame.getContentPane();

contentPane.setLayout(new FlowLayout());

btn1 = new JButton("OK");
btn2 = new JButton("Open");
btn3 = new JButton("Close");

contentPane.add(btn1);
contentPane.add(btn2);
contentPane.add(btn3);

frame.setSize(300,200);
frame.setVisible(true);
}
}

2.3执行结果

改变Frame的大小，Frame中组件的布局也会随之改变。

3.BorderLayout 布局管理器

3.1概述

BorderLayout是顶层窗口中内容窗格的默认布局管理器，被划分为BorderLayout.NORTH、BorderLayout.SOUTH、BorderLayout.WEST、BorderLayout.EAST、BorderLayout.CENTER
五个区域。

3.2构造函数

BorderLayout()
BorderLayout(int,int)

3.3示例代码

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

public class BorderLayoutDemo{
private JFrame frame;
private JButton be,bw,bn,bs,bc;

public static void main(String args[]){
BorderLayoutDemo that = new BorderLayoutDemo();
that.go();
}
public void go(){
frame = new JFrame("Border Layout");
be = new JButton("East");
bw = new JButton("West");
bn = new JButton("North");
bs = new JButton("South");
bc = new JButton("Center");

frame.getContentPane().add(be,"East");
frame.getContentPane().add(bw,BorderLayout.WEST);
frame.getContentPane().add(bn,BorderLayout.NORTH);
frame.getContentPane().add(bs,BorderLayout.SOUTH);
frame.getContentPane().add(bc,BorderLayout.CENTER);

frame.setSize(350,200);
frame.setVisible(true);
}
}

3.4执行结果

4.GridLayout布局管理器

4.1总述

是一种网格式的布局管理器，将窗口空间分割成若干行，乘若干列的网格。组件依次放入，占一格。

4.2构造函数

public GridLayout()
public GridLayout(int rows, int cols)

public GridLayout(int rows, int cols, int hgap, int vgap)

4.3参考代码

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

public class GridLayoutDemo{
private JFrame frame;
private JButton b1,b2,b3,b4,b5,b6;

public static void main(String args[]){
GridLayoutDemo that = new GridLayoutDemo();
that.go();
}
public void go(){
frame = new JFrame("Grid Frame");

Container contentPane = frame.getContentPane();

contentPane.setLayout(new GridLayout(3,2));

b1 = new JButton("grid_1");
b2 = new JButton("grid_2");
b3 = new JButton("grid_3");
b4 = new JButton("grid_4");
b5 = new JButton("grid_5");
b6 = new JButton("grid_6");

contentPane.add(b1);
contentPane.add(b2);
contentPane.add(b3);
contentPane.add(b4);
contentPane.add(b5);
contentPane.add(b6);

frame.pack();
frame.setVisible(true);
}
}

4.4执行结果

5.CardLayout
布局管理器

5.1总述

是一种卡片式的布局管理器，它将容器中的组件处理成一系列卡片，每一时刻只显示出其中一张。

5.2参考代码：

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

public class CardLayoutDemo extends MouseAdapter{
JPanel p1,p2,p3,p4,p5;
JLabel l1, l2, l3, l4, l5;

//declare a Cardlayout object
CardLayout myCard;
JFrame frame;
Container contentPane;

public static void main(String args[]){
CardLayoutDemo that = new CardLayoutDemo();
that.go();
System.out.println("test");
}

public void go(){
frame = new JFrame("Card Test");
contentPane = frame.getContentPane();
myCard = new CardLayout();

contentPane.setLayout(myCard);

p1=new JPanel();
p2 = new JPanel();
p3 = new JPanel();
p4 = new JPanel();
p5 = new JPanel();

//set the different bk color for each JPanel label
l1 =  new JLabel("This is the first JPanel");
p1.add(l1);
p1.setBackground(Color.yellow);

l2 =  new JLabel("This is the second JPanel");
p2.add(l2);
p2.setBackground(Color.green);

l3 =  new JLabel("This is the third JPanel");
p3.add(l3);
p3.setBackground(Color.magenta);

l4 =  new JLabel("This is the forth JPanel");
p4.add(l4);
p4.setBackground(Color.white);

l5 =  new JLabel("This is the fifth JPanel");
p5.add(l5);
p5.setBackground(Color.cyan);

//set mouseListener
p1.addMouseListener(this);
p2.addMouseListener(this);
p3.addMouseListener(this);
p4.addMouseListener(this);
p5.addMouseListener(this);

//set each JPanle as a Card to insert frame
contentPane.add(p1,"First");
contentPane.add(p2,"Sencond");
contentPane.add(p3,"Third");
contentPane.add(p4,"Forth");
contentPane.add(p5,"Fifth");

//display the first pic
myCard.show(contentPane,"First");
frame.setSize(300,200);
frame.show();
}

public void mouseClicked(MouseEvent e){
myCard.next(contentPane);
}
}

5.2执行结果

6.BoxLayout布局管理器

6.1总述

将容器中的组件，按水平排成一行，或按垂直方向排成一列。

6.2构造函数

BoxLayout(Container
target, int axis)
axis
= BoxLayout.X_AXIS | BoxLayout.Y_AXIS

6.3参考代码

import java.awt.*;
import javax.swing.*;
public class BoxLayoutDemo{

private JFrame frame;

private JPanel pv,ph;

public static void main(String args[]){

BoxLayoutDemo that = new BoxLayoutDemo();

that.go();

}
public void go(){

frame = new JFrame("Box Layout example");

Container contentPane = frame.getContentPane();

pv = new JPanel();

pv.setLayout(new BoxLayout(pv,BoxLayout.Y_AXIS));

pv.add(new JLabel("Monday"));

pv.add(new JLabel("Tuesday"));

pv.add(new JLabel("Wednesday"));

pv.add(new JLabel("Thursday"));

pv.add(new JLabel("Friday"));

pv.add(new JLabel("Saturday"));

pv.add(new JLabel("Sunday"));
contentPane.add(pv,BorderLayout.CENTER);

ph = new JPanel();
ph.setLayout(new BoxLayout(ph,BoxLayout.X_AXIS));

ph.add(new JButton("Yes"));

ph.add(new JButton("No"));

ph.add(new JButton("Cancle"));

contentPane.add(ph,BorderLayout.SOUTH);

frame.pack();

frame.setVisible(true);
}
}

6.4执行结果

6.5专门使用BoxLayout的特殊容器—Box类

6.5.1创建实例的静态方法

public static Box createHorizontalBox()
public static Box createVerticalBox()

6.5.2｜6.3的代码，改写如下

//the specific Box class for BoxLayout Container
import java.awt.*;
import javax.swing.*;

public class BoxDemo{
private JFrame frame;
private Box bv,bh;

public static void main(String arg[]){
BoxDemo that = new BoxDemo();
that.go();
}
void go(){
frame = new JFrame("Box Layout example");
Container contentPane = frame.getContentPane();

bv = Box.createVerticalBox();

bv.add(new JLabel("Monday"));
bv.add(new JLabel("Tuesday"));
bv.add(new JLabel("Wednesday"));
bv.add(new JLabel("Thursday"));
bv.add(new JLabel("Friday"));
bv.add(new JLabel("Saturday"));
bv.add(new JLabel("Sunday"));

contentPane.add(bv,BorderLayout.CENTER);

bh = Box.createHorizontalBox();
bh.add(new JButton("Yes"));
bh.add(new JButton("No"));
bh.add(new JButton("Cancel"));

contentPane.add(bh,BorderLayout.SOUTH);

frame.setSize(300,200);
//frame.pack();
frame.setVisible(true);
}
}

6.6Box类提供的创建不可组件方法

public static Component createHorizontalGlue()
public static Component createHorizontalStrut(int width)
public static Component createVerticalGlue()
public static Component createVerticalStrut(int height)
public static Component createRigidArea(Dimension d)

6.6.1参考代码

//to create invisible component
import java.awt.*;
import javax.swing.*;

public class GlueAndStrut{
private JFrame frame;
private Box b1,b2,b3,b4;

public static void main(String args[]){
GlueAndStrut that = new GlueAndStrut();
that.go();
}
void go(){
frame = new JFrame("Glue And Strut");
Container contentPane = frame.getContentPane();
contentPane.setLayout(new GridLayout(4,1));

b1 = Box.createHorizontalBox();
b1.add(new JLabel("Box 1:"));
b1.add(new JButton("Yes"));
b1.add(new JButton("No"));
b1.add(new JButton("Cancel"));

b2 = Box.createHorizontalBox();
b2.add(new JLabel("Box 2:"));
b2.add(new JButton("Yes"));
b2.add(new JButton("No"));
b2.add(Box.createHorizontalGlue());
b2.add(new JButton("Cancel"));

b3 = Box.createHorizontalBox();
b3.add(new JLabel("Box 3:"));
b3.add(new JButton("Yes"));
b3.add(new JButton("No"));
b3.add(Box.createHorizontalStrut(20));
b3.add(new JButton("Cancel"));

b4 = Box.createHorizontalBox();
b4.add(new JLabel("Box 4:"));
b4.add(new JButton("Yes"));
b4.add(new JButton("No"));
b4.add(Box.createRigidArea(new Dimension(10,10)));
b4.add(new JButton("Cancel"));

contentPane.add(b1);
contentPane.add(b2);
contentPane.add(b3);
contentPane.add(b4);

frame.setSize(300,200);
frame.setVisible(true);
}
}

6.6.2执行结果

7.不使用布局管理器

7.1一般做法

a.setLayout(null)将布局管理器设置为空
b.setBounds(int
x,int y,int width,int height) 设置组件的位置与大小

7.2参考代码

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

public class NullLayoutDemo{
private JFrame frame;
private JButton b1,b2,b3;

public static void main(String args[]){
NullLayoutDemo that = new NullLayoutDemo();
that.go();
}
private void go(){
frame = new JFrame("Null Layout Demo");
Container contentPane = frame.getContentPane();

//set the layout as null;
contentPane.setLayout(null);

//add the buttons
b1 = new JButton("Yes");
contentPane.add(b1);
b2 = new JButton("No");
contentPane.add(b2);
b3 = new JButton("Cancel");
contentPane.add(b3);

//set the buttons' pos and size;
b1.setBounds(30,15,75,20);
b2.setBounds(150,15,75,50);
b3.setBounds(150,100,75,20);

frame.setSize(300,200);
frame.setVisible(true);
}
}

7.3执行结果