welcomejframe.java

这是一个用Java编写的能够实现滚动字效果的小程序

//【例7.3】  设计滚动字演示线程状态及改变方法。

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

public class WelcomeJFrame extends JFrame
{
    private JDialog dialog;
    private JLabel label_dialog;

    public WelcomeJFrame(String[] texts)                   //texts指定移动字符串
    {                                                      //数组元素个数决定窗口中的面板数
        super("滚动字");
        
        this.setSize(400,300);
        this.setLocation(300,240);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);      //单击窗口关闭按钮时，结束程序运行
        
        if (texts==null || texts.length==0)
            this.add(new RollbyJPanel("Welcome!"));        //至少有一行字符串
        else
        {
            this.setLayout(new GridLayout(texts.length,1));//网格布局，1行若干列
            for (int i=0;i<texts.length;i++)
                this.add(new RollbyJPanel(texts[i])); 
        }
        this.setVisible(true);

        dialog = new JDialog(this,"提示",true);            //模式窗口
        dialog.setSize(240,80);
        label_dialog = new JLabel("",JLabel.CENTER);
        dialog.add(label_dialog); 
        dialog.setDefaultCloseOperation(HIDE_ON_CLOSE);    //单击对话框的关闭按钮时，隐藏对话框而不结束程序运行
    }
    
    public WelcomeJFrame()
    {
        this(null);
    }
    
    private class RollbyJPanel extends JPanel implements ActionListener, Runnable
    {                                            //自定义面板类，私有内部类，实现单击事件监听器接口和线程接口
        private JTextField text_word,text_sleep;           //滚动字文本行，线程睡眠时间文本行
        private JButton button_start,button_interrupt;     //启动按钮，中断按钮
        private JTextField text_state;                     //线程状态文本行

        private Thread thread_rollby;                      //线程对象
        private int sleeptime;                             //线程睡眠时间

        private RollbyJPanel(String text)                  //内部面板类构造方法
        {
            this.setLayout(new GridLayout(2,1));
            
            for(int i=0;i<100;i++)                         //为字符串添加空格
                text = text + " ";
            text_word = new JTextField(text);
            this.add(text_word);

            JPanel panel_sub = new JPanel(new FlowLayout(FlowLayout.LEFT)); 
            this.add(panel_sub);
            panel_sub.add(new JLabel("sleep"));
            
            this.sleeptime = (int)(Math.random()*100);
            text_sleep = new JTextField(""+sleeptime,5);
            panel_sub.add(text_sleep);
            text_sleep.addActionListener(this);
            
            button_start = new JButton("启动");
            panel_sub.add(button_start);
            button_start.addActionListener(this);
            
            button_interrupt = new JButton("中断");
            panel_sub.add(button_interrupt);
            button_interrupt.addActionListener(this);

            thread_rollby = new Thread(this);              //创建线程对象，目标对象是当前对象
            button_interrupt.setEnabled(false);            //设置中断按钮为无效状态

            panel_sub.add(new JLabel("state"));
            text_state = new JTextField(""+thread_rollby.getState(),10);
            text_state.setEditable(false);
            panel_sub.add(text_state);
        }

        public void run()                                  //线程体，必须是公有方法    
        {
            while (thread_rollby.isAlive() && !thread_rollby.isInterrupted())
            {                                              //线程活动且没中断时
                try
                {
                    String str = text_word.getText();
                    str = str.substring(1)+ str.substring(0,1);
                    text_word.setText(str);
                    thread_rollby.sleep(sleeptime);        //线程睡眠，抛出异常
                }
                catch(InterruptedException e)
                {
                    break;                                 //退出循环
                }
            }
        }                                                  //run()方法结束，线程对象终止

        public void actionPerformed(ActionEvent e)         //单击事件处理，必须是公有方法
        {
            if(e.getSource()==button_start)                //单击启动按钮时
            {
                thread_rollby = new Thread(this);          //重新创建一个线程对象
                thread_rollby.start();
                text_state.setText(""+thread_rollby.getState()); //显示线程状态
                button_start.setEnabled(false);
                button_interrupt.setEnabled(true);
            }
            
            if(e.getSource()==button_interrupt)            //单击中断按钮时
            {
                thread_rollby.interrupt();                 //设置当前线程对象中断标记
                text_state.setText(""+thread_rollby.getState()); 
                button_start.setEnabled(true);
                button_interrupt.setEnabled(false);
            }

            if(e.getSource()==text_sleep)                  //单击线程睡眠时间文本行时
            {
                try
                {
                    sleeptime = Integer.parseInt(text_sleep.getText());
                }
                catch(NumberFormatException nfe)
                {
                    label_dialog.setText("\""+text_sleep.getText()+"\" 不能转换成整数，请重新输入!");
                    dialog.setLocation(this.getX()+100,this.getY()+100);
                    dialog.setVisible(true);
                }
            }
        }
    }

    public static void main(String arg[])
    {
        String[] texts={"Welcome","Hello","Rollby"};
        new WelcomeJFrame(texts);
    }
}

/*
        new WelcomeJFrame();
相当于
        String[] texts={"Welcome"};
        new WelcomeJFrame(texts);

*/