实验十四 Swing程序设计（二）

一、实验预热
1、请解释什么是事件，什么是事件源，什么是事件监听接口，并各举出例子。
事件：一般继承自java.util.EventObject类，封装了事件源对象及跟事件相关的信息。
事件源：事件发生的地方，由于事件源的某项属性或状态发生了改变（比如button被单击、textbox的值发生改变等等）导致某项事件发生，换句话说就是生成了相应的事件对象。因为事件监听器要注册在事件源上，所以事件源类中应该要有包含监听器的容器（List、Set等等）。
事件监听器：实现java.util.EventListener接口，注册在事件源上，当事件源的属性或状态改变时，取得相应的监听器调用其内部的回调方法。

2、Swing编程中处理事件的一般流程是什么？
实现事件监听接口
实例化接口对象
将监听器与事件源绑定
复写接口的抽象方法

二、实验内容
1、请用java编写一个计算器，外观布局设计没有特殊要求，计算器功能必须至少要包含加、减、乘、除四种运算。运算结果要显示在GUI结果文本框中，计算器数字和运算符按键必须在GUI上显示，用户可以直接通过按键进行输入而得到计算结果。
代码：

package leif.tests;

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class ExperimentalReport extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;

    private class WindowCloser extends WindowAdapter {
        @Override
        public void windowClosing(WindowEvent we) {
            System.exit(0);
        }
    }

    private static final String[] CALCULATOR = {"7", "8", "9", "/", "4", "5", "6", "*", "1", "2", "3", "-", ".", "0", "=", "+"};
    JButton[] buttons = new JButton[CALCULATOR.length];
    JButton reset = new JButton("CE");
    JTextField display = new JTextField("0");

    public ExperimentalReport() {
        super("Calculator");
        JPanel button = new JPanel(new GridLayout(4, 4));

        for (int i = 0; i < CALCULATOR.length; i++) {
            buttons[i] = new JButton(CALCULATOR[i]);
            button.add(buttons[i]);
        }

        JPanel dial = new JPanel(new BorderLayout());
        dial.add("Center", display);
        dial.add("East", reset);
        getContentPane().setLayout(new BorderLayout());
        getContentPane().add("North", dial);
        getContentPane().add("Center", button);

        for (int i = 0; i < CALCULATOR.length; i++) {
            buttons[i].addActionListener(this);
        }

        reset.addActionListener(this);
        display.addActionListener(this);
        addWindowListener(new WindowCloser());
        setSize(800, 800);
        setVisible(true);
        pack();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        Object target = e.getSource();
        String label = e.getActionCommand();

        if (target == reset) {
            handleReset();
        } else if ("0123456789.".indexOf(label) > 0) {
            handleNumber(label);
        } else {
            handleOperator(label);
        }
    }

    boolean isFirstDigit = true;

    public void handleNumber(String key) {
        if (isFirstDigit) {
            display.setText(key);
        } else if ((key.equals(".")) && (display.getText().indexOf(".") < 0)) {
            display.setText(display.getText() + ".");
        } else if (!key.equals(".")) {
            display.setText(display.getText() + key);
        }

        isFirstDigit = false;
    }

    public void handleReset() {
        display.setText("0");
        isFirstDigit = true;
        operator = "=";
    }

    double number = 0.0;
    String operator = "=";

    public void handleOperator(String key) {
        if (operator.equals("+")) {
            number += Double.valueOf(display.getText());
        } else if (operator.equals("-")) {
            number -= Double.valueOf(display.getText());
        } else if (operator.equals("*")) {
            number *= Double.valueOf(display.getText());
        } else if (operator.equals("/")) {
            number /= Double.valueOf(display.getText());
        } else if (operator.equals("=")) {
            number = Double.valueOf(display.getText());
        }

        display.setText(String.valueOf(number));
        operator = key;
        isFirstDigit = true;
    }

    public static void main(String[] args) {
        new ExperimentalReport();
    }
}

结果截图：

image.png

2、请编写一个进度条程序，界面包含一个拷贝进度条，和一个拷贝开始按钮，当拷贝结束时在UI上显示拷贝完成字样，同时要求进度条和拷贝实际速度基本同步。
代码：

package leif.tests;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
import javax.swing.WindowConstants;

public class ExperimentalReport extends JFrame {
    private static final long serialVersionUID = 1L;
    JProgressBar jProgressBar = new JProgressBar();
    private static Thread thread;
    private int flag = 1;

    public ExperimentalReport() {
        setSize(300, 200);
        setLayout(null);
        setTitle("拷贝进度条");
        setVisible(true);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        jProgressBar.setOrientation(JProgressBar.HORIZONTAL);
        jProgressBar.setSize(150, 50);
        jProgressBar.setMinimum(0);
        jProgressBar.setMaximum(100);
        jProgressBar.setBorderPainted(true);
        jProgressBar.setBounds(50, 50, 200, 20);
        jProgressBar.setStringPainted(true);
        jProgressBar.setIndeterminate(false);
        jProgressBar.setForeground(Color.green);
        JButton jButton = new JButton("开始");
        jButton.setBounds(110, 100, 70, 30);
        add(jProgressBar);
        add(jButton);
        jButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (flag == 1) {
                    thread.start();
                    flag++;
                }
            }
        });

        thread = new Thread(new Runnable() {
            @Override
            public void run() {
                File file1 = new File("C:\\Users\\Administrator\\Desktop\\user.sql");

                if (!file1.exists()) {
                    System.out.println("源文件不存在");
                    System.exit(0);
                }

                File file2 = new File("C:\\Users\\Administrator\\Desktop\\user1.sql");
                long Length = file1.length();
                int progress = 1;
                byte[] bytes = new byte[(int)(Length / 100)];
                FileInputStream fileInputStream = null;
                FileOutputStream fileOutputStream = null;

                try {
                    fileInputStream = new FileInputStream(file1);
                    fileOutputStream = new FileOutputStream(file2);

                    while (fileInputStream.read(bytes) != -1) {
                        fileOutputStream.write(bytes);
                        jProgressBar.setValue(progress);
                        progress++;
                        Thread.sleep(100);
                    }

                    jProgressBar.setString("拷贝完成！");
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    try {
                        fileInputStream.close();
                        fileOutputStream.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
    }

    public static void main(String args[]) {
        new ExperimentalReport();
    }
}

结果截图：

image.png