Java MessagePanel

一个小测试，MessagePanel继承于Panel,显示结果为：

  1 import java.awt.*;

  2 

  3 import javax.swing.*;

  4 

  5 public class hello extends JFrame{

  6     public hello(){

  7         MessagePanel mp1=new MessagePanel("Welcome to Java");

  8         MessagePanel mp2=new MessagePanel("Java is fun");

  9         MessagePanel mp3=new MessagePanel("Java is cool");

 10         MessagePanel mp4=new MessagePanel("I love Java");

 11         

 12         mp1.setFont(new Font("SansSerif",Font.ITALIC,20));

 13         mp2.setFont(new Font("Courier",Font.BOLD,20));

 14         mp3.setFont(new Font("Times",Font.ITALIC,20));

 15         mp4.setFont(new Font("Californian FB",Font.PLAIN,20));

 16         

 17         mp1.setBackground(Color.red);

 18         mp2.setBackground(Color.cyan);

 19         mp3.setBackground(Color.green);

 20         mp4.setBackground(Color.white);

 21         mp1.setCentered(true);

 22         

 23         setLayout(new GridLayout(2,2));

 24         add(mp1);

 25         add(mp2);

 26         add(mp3);

 27         add(mp4);

 28     }

 29     

 30     public static void main(String[] args){

 31         hello frame=new hello();

 32         frame.setSize(300,200);

 33         frame.setTitle("Test MessagePanel");

 34         frame.setLocationRelativeTo(null);

 35         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

 36         frame.setVisible(true);

 37     }

 38 }

 39 

 40 

 41 class MessagePanel extends JPanel{

 42     private String message="Welcome to Java";

 43     private int xCoordinate=20;

 44     private int yCoordinate=20;

 45     private boolean centered;

 46     private int interval=10;

 47     public MessagePanel(){}

 48     public MessagePanel(String message){

 49         this.message=message;

 50     }

 51     public String getMessage(){

 52         return message;

 53     }

 54     public void getMessage(String message){

 55         this.message=message;

 56     }

 57     public int getXCoordinate(){

 58         return xCoordinate;

 59     }

 60     public void setXCoordinate(int x){

 61         this.xCoordinate=x;

 62         repaint();

 63     }

 64      public int getYCoordinate(){

 65         return yCoordinate;

 66     }

 67     public void setYCoordinate(int y){

 68         this.yCoordinate=y;

 69         repaint();

 70     }

 71     public boolean isCentered(){

 72         return centered;

 73     }

 74     public void setCentered(boolean centered){

 75         this.centered=centered;

 76         repaint();

 77     }

 78     

 79     public int getInterval(){

 80         return interval;

 81     }

 82     

 83     public void setinterVal(int interval){

 84         this.interval=interval;

 85         repaint();

 86     }

 87     protected void paintComponent(Graphics g){

 88         super.paintComponent(g);

 89         if(centered){

 90             FontMetrics fm = g.getFontMetrics();

 91             int stringWidth=fm.stringWidth(message);

 92             int stringAscent=fm.getAscent();

 93             xCoordinate=getWidth()/2-stringWidth/2;

 94             yCoordinate=getHeight()/2-stringAscent/2;

 95         }

 96         g.drawString(message, xCoordinate, yCoordinate);

 97     }

 98     public void moveLeft(){

 99         xCoordinate-=interval;

100         repaint();

101     }

102     public void moveRight(){

103         xCoordinate+=interval;

104         repaint();

105     }

106 

107     public void moveUp(){

108         yCoordinate-=interval;

109         repaint();

110     }

111     public void moveDown(){

112         yCoordinate+=interval;

113         repaint();

114     }

115     public Dimension getPreferredSize(){

116         return new Dimension(200,30);

117     }

118     

119 }