GUI SWING从入门到精通

****************************************************************************************************************************************************************************

1、百闻不如一经历
package com.day;
import com.day.pojo.SonFrame;

// 主函数入口
public class DayApplication {

    public static void main(String[] args) {
        new SonFrame();
    }
}
*******************************************************************
package com.day.pojo;

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

public class SonPanel1 extends JPanel {
    JButton click;

    public SonPanel1() {
        click = new JButton("点击");
        SonFrame.addClickListener(click);
        this.add(click);
        this.setLocation(500, 0);
        this.setPreferredSize(new Dimension(600, 300));
        this.setBackground(Color.red);
        this.setVisible(true);
    }
}
*******************************************************************
package com.day.pojo;

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

public class SonPanel2 extends JPanel {
    JButton touch;

    public SonPanel2() {
        touch = new JButton("触摸");
        SonFrame.addClickListener(touch);
        this.add(touch);
        this.setLocation(500, 250);
        this.setPreferredSize(new Dimension(600, 300));
        this.setBackground(Color.black);
        this.setVisible(true);
    }
}
*******************************************************************
package com.day.pojo;

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

public class SonFrame extends JFrame {
    static SonPanel1 sonPanel1 = new SonPanel1();
    static SonPanel2 sonPanel2 = new SonPanel2();

    public SonFrame() {
        // 流式布局
        this.setLayout(new FlowLayout());
        this.add(sonPanel1);
        this.add(sonPanel2);
        this.setLocation(500, 250);
        this.setSize(600, 600);
        this.setTitle("主体视图");
        this.setVisible(true);
        this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }

    public static void addClickListener(JButton jButton) {
        jButton.addActionListener(e -> { // lambda表达式
            String buttonInfo = e.getActionCommand();
            SonFrame temp = (SonFrame) jButton.getParent().getParent().getParent().getParent().getParent();
            switch (buttonInfo) {
                case "点击":
                    sonPanel1.setVisible(false);
                    sonPanel2.setVisible(true);
                    temp.setTitle("展示的是面板2");
                    break;
                case "触摸":
                    sonPanel1.setVisible(true);
                    sonPanel2.setVisible(false);
                    temp.setTitle("展示的是面板1");
                    break;
            }
        });
    }
}
************************************************
JOptionPane.showMessageDialog
        (this, "恭喜您全部答对！", "提示", JOptionPane.WARNING_MESSAGE);
************************************************
TextField比JTextField好用，JTextField会导致无法输入，程序卡不动。

****************************************************************************************************************************************************************************

1、GUI编程概述
【1】组件：窗口。弹窗。面板。文本框。列表框。按钮。图片。监听事件。鼠标事件。键盘事件。外挂。IDEA破解工具。
【2】SWING、AWT核心开发技术。因为界面丑所以不太广泛应用。主要是可以写小工具。重点了解监听。

****************************************************************************************************************************************************************************

2、AWT
【1】万物皆对象。包含了很多类与接口。GUI：图形用户界面编程。
【2】元素：窗口。按钮。文本框
【3】核心类：组件Component（按钮、文本、标签...）。Container容器（Windows Frame、Dialog、面板Panel Applet）

****************************************************************************************************************************************************************************

3、Frame操作
  Frame frame = new Frame("第一个图形窗口");
            frame.setSize(600, 600);
            frame.setVisible(true);
            frame.setBackground(Color.pink);
            frame.setLocation(20, 20);
            // 设置大小固定
            frame.setResizable(false);

****************************************************************************************************************************************************************************

4、面板Panel
 Frame frame = new Frame();
        Panel panel = new Panel();
        // 设置布局
        frame.setLayout(null);
        frame.setBounds(300, 300, 500, 500);
        frame.setBackground(Color.PINK);
        // panel设置
        panel.setBounds(50, 50, 400, 400);
        panel.setBackground(Color.CYAN);

        frame.add(panel);
        frame.setVisible(true);

        // 监听窗口关闭
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

****************************************************************************************************************************************************************************

5、布局管理
【1】流式布局 FlowLayout。BorderLayout 东西南北中布局。表格布局GridLayout。
【2】先思考80%。代码20%。不要上来就写代码。

****************************************************************************************************************************************************************************

6、事件监听
【1】当某个事情发的时候，需要干什么。
  Frame frame = new Frame();
        Button button_1 = new Button();
        frame.add(button_1);
        frame.setSize(600, 600);
        frame.setVisible(true);
        // 按钮监听
        button_1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                button_1.setLabel("add label");
            }
        });
        // 关闭监听
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

****************************************************************************************************************************************************************************

8、计算器
【1】组合（一个类在另一个类作为成员变量使用）大于继承
【2】内部类最大的好处，就是可以畅通无阻的访问外部类
package com.day.pojo;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class Update {
    TextField textField_1, textField_2, textField_3;

    public void loadFrame() {
        // 窗体
        Frame frame = new Frame();
        frame.setLayout(new FlowLayout());

        // 3个文本框
        textField_1 = new TextField(10); // 字符数指定
        textField_2 = new TextField(10);
        textField_3 = new TextField(20);

        // 1个按钮
        Button button = new Button("=");
        button.addActionListener(new MyActionListener());

        // 1个标签
        Label label = new Label("+");

        // 布局
        frame.add(textField_1);
        frame.add(label);
        frame.add(textField_2);
        frame.add(button);
        frame.add(textField_3);

        // 设置可见
        frame.setSize(600, 600);
        frame.setVisible(true);
        // 设置点击可关闭
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }

    private class MyActionListener implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            // 1. 获得操作的数 2.将值加法运算 3.放到3个框，清空12框
            int num_1 = Integer.parseInt(textField_1.getText());
            int num_2 = Integer.parseInt(textField_2.getText());
            int num_3 = num_1 + num_2;
            textField_1.setText("");
            textField_2.setText("");
            textField_3.setText(num_3 + "");
        }
    }
}
【3】我的思路
package com.day.pojo;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class Calculator {
    public Calculator() {
        // 窗体
        Frame frame = new Frame();
        frame.setLayout(new FlowLayout());

        // 3个文本框
        TextField textField_1 = new TextField(10); // 字符数指定
        TextField textField_2 = new TextField(10);
        TextField textField_3 = new TextField(20);

        // 1个按钮
        Button button = new Button("=");
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // 1. 获得操作的数 2.将值加法运算 3.放到3个框，清空12框
                int num_1 = Integer.parseInt(textField_1.getText());
                int num_2 = Integer.parseInt(textField_2.getText());
                int num_3 = num_1 + num_2;
                textField_1.setText("");
                textField_2.setText("");
                textField_3.setText(num_3 + "");
            }
        });

        // 1个标签
        Label label = new Label("+");

        // 布局
        frame.add(textField_1);
        frame.add(label);
        frame.add(textField_2);
        frame.add(button);
        frame.add(textField_3);

        // 设置可见
        frame.setSize(600, 600);
        frame.setVisible(true);
        // 设置点击可关闭
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }
}

****************************************************************************************************************************************************************************

9、画笔
【1】实际代码
package com.day.pojo;

import java.awt.*;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class MyPaint {

    public void doWork() {
        Frame frame = new Frame() {
            @Override
            public void paint(Graphics g) {
                // super.paint(graphics);
                g.setColor(Color.red);
                g.drawOval(100, 100, 100, 100);
                g.fill3DRect(200, 200, 100, 100, false);
                // 养成习惯，画笔用完，把他还原成最初的颜色
            }
        };
        frame.setSize(600, 600);

        frame.setVisible(true);
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }
}

****************************************************************************************************************************************************************************

10、鼠标监听事件
【1】另一种思路
package com.day.pojo;

import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.Iterator;

public class MyFrame {
    private ArrayList myPointList = new ArrayList<MyPoint>();

    public void doWork() {
        Frame frame = new Frame() {
            @Override
            public void paint(Graphics g) {
                Iterator iterator = myPointList.iterator();
                while (iterator.hasNext()) {
                    MyPoint myPoint = (MyPoint) iterator.next();
                    g.setColor(Color.BLACK);
                    g.fillOval(myPoint.getX(), myPoint.getY(), 10, 10);
                }
                this.addWindowListener(new WindowAdapter() {
                    @Override
                    public void windowClosing(WindowEvent e) {
                        System.exit(0);
                    }
                });
            }
        };
        // 因为frame为空无法repaint，所以要单独再添加
        frame.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println(e.getX());
                myPointList.add(new MyPoint(e.getX(), e.getY()));
                frame.repaint();
            }
        });

        frame.setSize(600, 600);
        frame.setTitle("画图");
        frame.setVisible(true);
    }
}

****************************************************************************************************************************************************************************

11、窗口监听事件
【1】我已经无师自通，使用了匿名内部类
【2】主要也是关闭事件，别的用的很少
 Frame frame = new Frame() {
            @Override
            public void paint(Graphics g) {
                Iterator iterator = myPointList.iterator();
                while (iterator.hasNext()) {
                    MyPoint myPoint = (MyPoint) iterator.next();
                    g.setColor(Color.BLACK);
                    g.fillOval(myPoint.getX(), myPoint.getY(), 10, 10);
                }
                this.addWindowListener(new WindowAdapter() {
                    @Override
                    public void windowClosing(WindowEvent e) {
                        System.exit(0);
                    }
                });
            }
        };

****************************************************************************************************************************************************************************

13、键盘监听事件
【1】开发游戏会用到，和键盘窗口差不多
package com.day.pojo;

import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.Iterator;

public class MyFrame {
    private ArrayList myPointList = new ArrayList<MyPoint>();

    public void doWork() {
        Frame frame = new Frame() {
            @Override
            public void paint(Graphics g) {
                this.addWindowListener(new WindowAdapter() {
                    @Override
                    public void windowClosing(WindowEvent e) {
                        System.exit(0);
                    }
                });
            }
        };
        // 因为frame为空无法repaint，所以要单独再添加
        frame.addKeyListener(new KeyAdapter() {
            @Override
            public void keyPressed(KeyEvent e) {
                //System.out.println(e.getKeyCode()); // 不用记录数组，用KeyEvent.XXX即可
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    System.out.println("按下了Enter键盘");
                }
            }
        });

        frame.setSize(600, 600);
        frame.setTitle("画图");
        frame.setVisible(true);
    }
}

****************************************************************************************************************************************************************************

14、Swing之JFrame窗体
【1】对我来说太简单了
package com.day.pojo;

import javax.swing.*;

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");

        JLabel jLabel = new JLabel("HIT GUI开发");
        jLabel.setHorizontalAlignment(SwingConstants.CENTER);

        jFrame.add(jLabel);

        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

****************************************************************************************************************************************************************************

15、JDialog弹窗
【1】看实现代码
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 按钮
        JButton jButton = new JButton("点击弹出一个对话框");
        jButton.setBounds(30, 30, 200, 50);
        // 监听事件
        jButton.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                // 弹窗
                MyDialog myDialog = new MyDialog();
            }
        });

        container.add(jButton);

        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

class MyDialog {
    public MyDialog() {
        // 弹窗
        JDialog jDialog = new JDialog();
        jDialog.setVisible(true);
        jDialog.setBounds(100, 100, 500, 500);
        Container container = jDialog.getContentPane();
        container.add(new Label("HIT Window"));
    }
}

****************************************************************************************************************************************************************************

16、Icon、ImageIcon标签
【1】标签：Label。
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        Icon icon = new Icon() {
            @Override
            public void paintIcon(Component c, Graphics g, int x, int y) {
                g.fillOval(x, 23, 15, 15);
            }

            @Override
            public int getIconWidth() {
                return 0;
            }

            @Override
            public int getIconHeight() {
                return 0;
            }
        };

        JLabel jLabel = new JLabel("     标签", icon, SwingConstants.CENTER);
        jLabel.setBounds(0, 0, 60, 60);
        jLabel.setBackground(Color.RED);

        container.add(jLabel);

        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}
【2】图片
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        ImageIcon imageIcon = new ImageIcon("src/main/resources/1.jpg");

        JLabel jLabel = new JLabel("     标签", imageIcon, SwingConstants.CENTER);
        jLabel.setBounds(100, 100, 300, 300);
        container.add(jLabel);

        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

****************************************************************************************************************************************************************************

17、文本域JScroll面板
【1】JPanel
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 面板
        JPanel jPanel = new JPanel();
        jPanel.setBounds(0, 0, 100, 100);
        jPanel.add(new JButton("HIT按钮_1"));

        container.add(jPanel);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}
【2】动态面板
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 文本域
        JTextArea jTextArea = new JTextArea(50, 50);
        jTextArea.setText("欢迎学习JAVA GUI");

        // Scroll面板
        JScrollPane jScrollPane = new JScrollPane(jTextArea);
        jScrollPane.setBounds(200, 200, 200, 200);


        container.add(jScrollPane);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

****************************************************************************************************************************************************************************

18、图片按钮、单选框、多选框
【1】图片按钮
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 图片按钮
        ImageIcon imageIcon = new ImageIcon("src/main/resources/1.jpg");
        JButton jButton = new JButton(imageIcon);
        jButton.setBounds(0, 0, 300, 300);

        container.add(jButton);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}
【2】单选框
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 选框
        JRadioButton jRadioButton_1 = new JRadioButton("单选按钮_1");
        jRadioButton_1.setBounds(0, 0, 100, 50);
        JRadioButton jRadioButton_2 = new JRadioButton("单选按钮_2");
        jRadioButton_2.setBounds(150, 0, 100, 50);
        JRadioButton jRadioButton_3 = new JRadioButton("单选按钮_3");
        jRadioButton_3.setBounds(300, 0, 100, 50);
        ButtonGroup buttonGroup = new ButtonGroup();
        // 一个组智能选择一个
        buttonGroup.add(jRadioButton_1);
        buttonGroup.add(jRadioButton_2);
        buttonGroup.add(jRadioButton_3);

        container.add(jRadioButton_1);
        container.add(jRadioButton_2);
        container.add(jRadioButton_3);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}
【3】多选框
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 选框
        JCheckBox jCheckBox_1 = new JCheckBox("多选_1");
        jCheckBox_1.setBounds(0, 0, 100, 50);
        JCheckBox jCheckBox_2 = new JCheckBox("多选_2");
        jCheckBox_2.setBounds(100, 0, 100, 50);

        container.add(jCheckBox_1);
        container.add(jCheckBox_2);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

****************************************************************************************************************************************************************************

19、下拉框、列表框
【1】下拉框：选择一些单个选项
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 下拉框
        JComboBox jComboBox = new JComboBox();
        jComboBox.setBounds(100, 100, 200, 30);
        jComboBox.addItem(null);
        jComboBox.addItem("正在上映");
        jComboBox.addItem("即将上映");

        container.add(jComboBox);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}
【2】列表框：展示一些信息，动态扩容
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 下拉框
        String[] myArray = {"1", "2", "3"};
        JList jList = new JList(myArray);
        jList.setBounds(100, 100, 100, 100);


        container.add(jList);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

****************************************************************************************************************************************************************************

20、文本框、密码框、文本域
【1】文本框
package com.day.pojo;
import javax.swing.*;
import java.awt.*;
public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 文本框
        JTextField jTextField = new JTextField("Hello");
        jTextField.setBounds(100, 100, 100, 30);

        container.add(jTextField);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}
【2】密码框
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 文本框
        JPasswordField jPasswordField = new JPasswordField();
        jPasswordField.setBounds(100, 100, 100, 30);
        jPasswordField.setEchoChar('*');

        container.add(jPasswordField);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}
【3】文本域
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 获取当前容器，放内容
        Container container = jFrame.getContentPane();
        // 绝对布局
        container.setLayout(null);

        // 文本框
        JTextArea jTextArea = new JTextArea("文本区域");
        jTextArea.setBounds(100, 100, 100, 30);
        // 面板
        JScrollPane jScrollPane = new JScrollPane(jTextArea);
        jScrollPane.setBounds(100, 100, 100, 30);

        container.add(jScrollPane);
        jFrame.setSize(600, 600);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

****************************************************************************************************************************************************************************

21、贪吃蛇界面绘制
【1】帧：如果时间足够小，就是动画，一秒30帧 60帧。连起来是动画，拆开就是静态的图片。
package com.day.pojo;

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

public class MyFrame {
    public void doWork() {
        JFrame jFrame = new JFrame("这是JFrame窗口");

        // 游戏面板
        JPanel jPanel = new JPanel() {
            // 游戏里的所有东西都使用这个画笔
            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g); // 清屏用的
                this.setBackground(Color.WHITE);
                //Data.headImageIcon.paintIcon(this, g, 25, 11); // 广告的位置
                g.fillRect(25, 75, 850, 600); // 默认游戏界面
            }
        };
        JLabel jLabel = new JLabel("", Data.headImageIcon, SwingConstants.CENTER); // 这么用很快
        jPanel.add(jLabel);

        jFrame.add(jPanel);
        jFrame.setSize(900, 720);
        jFrame.setResizable(false);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}
----------------------------------
package com.day.pojo;

import javax.swing.*;

public class Data {
    public static ImageIcon headImageIcon = new ImageIcon("src/main/resources/res/head.jpg");

    public static ImageIcon upImageIcon = new ImageIcon("src/main/resources/res/up.png");
    public static ImageIcon downImageIcon = new ImageIcon("src/main/resources/res/down.png");
    public static ImageIcon leftImageIcon = new ImageIcon("src/main/resources/res/left.png");
    public static ImageIcon rightImageIcon = new ImageIcon("src/main/resources/res/right.png");

    public static ImageIcon bodyImageIcon = new ImageIcon("src/main/resources/res/body.png");
    public static ImageIcon foodImageIcon = new ImageIcon("src/main/resources/res/food.png");
}

****************************************************************************************************************************************************************************

22-26、贪吃蛇实战（自己解决了一个BUG）
package com.day.pojo;

import javax.swing.*;

public class Data {
    public static ImageIcon headImageIcon = new ImageIcon("src/main/resources/image/head.jpg");

    public static ImageIcon upImageIcon = new ImageIcon("src/main/resources/image/up.png");
    public static ImageIcon downImageIcon = new ImageIcon("src/main/resources/image/down.png");
    public static ImageIcon leftImageIcon = new ImageIcon("src/main/resources/image/left.png");
    public static ImageIcon rightImageIcon = new ImageIcon("src/main/resources/image/right.png");

    public static ImageIcon bodyImageIcon = new ImageIcon("src/main/resources/image/body.png");
    public static ImageIcon foodImageIcon = new ImageIcon("src/main/resources/image/food.png");
}
*********************************
package com.day.pojo;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.Random;

public class GamePanel extends JPanel implements KeyListener, ActionListener {
    // 构造函数的使用
    public GamePanel() {
        // new对象时就执行
        JLabel jLabel = new JLabel(new ImageIcon("src/main/resources/image/head.jpg"));
        this.add(jLabel);
        init();
        this.setFocusable(true); //获取焦点
        this.addKeyListener(this);
        timer.start(); // 开启定时器
    }

    // 定义蛇的数据结构
    int length; // 小蛇的长度
    int[] snakeX = new int[600]; // 小蛇的X坐标
    int[] snakeY = new int[500]; // 小蛇的Y坐标
    String direct;// 方向
    boolean startFlag = false;

    //食物的出现
    int foodX;
    int foodY;
    Random random = new Random();

    // 是否失败
    boolean failFlag = false;
    Integer score;
    String beforePress;

    // 初始化小蛇
    public void init() {
        length = 3;
        direct = "R";
        // 头
        snakeX[0] = 160;
        snakeY[0] = 80;
        // 身体1
        snakeX[1] = 80;
        snakeY[1] = 80;
        //身体2
        snakeX[2] = 0;
        snakeY[2] = 80;
        // 食物随机分布
        foodX = 80 + 80 * random.nextInt(9);
        foodY = 80 + 80 * random.nextInt(9);
        score = 0;
    }

    // 定时刷新
    Timer timer = new Timer(150, this);

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g); // 清屏用的
        this.setBackground(Color.WHITE);
        //Data.headImageIcon.paintIcon(this, g, 25, 11); // 广告的位置
        g.fillRect(25, 75, 880, 880); // 默认游戏界面
        // 画积分
        g.setColor(Color.white);
        g.setFont(new Font("微软雅黑", Font.BOLD, 40));
        g.drawString("长度 " + length, 750, 120);
        g.drawString("分数 " + score, 750, 180);

        // 画食物
        Data.foodImageIcon.paintIcon(this, g, foodX, foodY);
        // 画小蛇
        System.out.println(beforePress);
        switch (direct) {
            case "R":
                if (beforePress != null && !beforePress.equals("L")) {
                    Data.rightImageIcon.paintIcon(this, g, snakeX[0], snakeY[0]);
                    break;
                }
            case "L":
                if (beforePress != null && !beforePress.equals("R")) {
                    Data.leftImageIcon.paintIcon(this, g, snakeX[0], snakeY[0]);
                    break;
                }
            case "U":
                if (beforePress != null && !beforePress.equals("D")) {
                    Data.upImageIcon.paintIcon(this, g, snakeX[0], snakeY[0]);
                    break;
                }
            case "D":
                if (beforePress != null && !beforePress.equals("U")) {
                    Data.downImageIcon.paintIcon(this, g, snakeX[0], snakeY[0]);
                    break;
                }
        }
        beforePress = direct;
        for (int i = 1; i < length; i++) {
            Data.bodyImageIcon.paintIcon(this, g, snakeX[i], snakeY[i]);
        }
        // 游戏状态
        if (!startFlag) {
            g.setColor(Color.white);
            g.setFont(new Font("微软雅黑", Font.BOLD, 40));
            g.drawString("按下空格开始游戏", 300, 300);
        }
        // 判断是否失败
        if (failFlag) {
            g.setColor(Color.red);
            g.setFont(new Font("微软雅黑", Font.BOLD, 40));
            g.drawString("游戏失败，按下空格重新开始！！！", 300, 300);
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (startFlag && !failFlag) {
            // System.out.println(snakeX[0] + "VS" + foodX);
            //System.out.println(snakeY[0] + "VS" + foodY);
            if (foodX == snakeX[0] && foodY == snakeY[0]) {
                length++;// 长度+1
                score = score + 10;
                // 重新生成食物
                foodX = 80 + 80 * random.nextInt(9);
                foodY = 80 + 80 * random.nextInt(9);
            }
            // 右移动
            for (int i = length; i > 0; i--) {
                snakeX[i] = snakeX[i - 1];
                snakeY[i] = snakeY[i - 1];
            }
            switch (direct) {
                case "R":
                    snakeX[0] = snakeX[0] + 80;
                    if (snakeX[0] > 880) {
                        snakeX[0] = 30;
                    }
                    break;
                case "L":
                    snakeX[0] = snakeX[0] - 80;
                    if (snakeX[0] < 0) {
                        snakeX[0] = 880;
                    }
                    break;
                case "U":
                    snakeY[0] = snakeY[0] - 80;
                    if (snakeY[0] < 0) {
                        snakeY[0] = 880;
                    }
                    break;
                case "D":
                    snakeY[0] = snakeY[0] + 80;
                    if (snakeY[0] > 880) {
                        snakeY[0] = 0;
                    }
                    break;
            }
            // 判断失败
            for (int i = 1; i < length; i++) {
                if (snakeX[0] == snakeX[i] && snakeY[0] == snakeY[i]) {
                    failFlag = true;
                }
            }
            this.repaint(); //重画页面
        }
    }

    @Override
    public void keyTyped(KeyEvent e) {

    }

    @Override
    public void keyPressed(KeyEvent e) {
        //System.out.println(e.getKeyCode());
        int keyCode = e.getKeyCode();
        if (keyCode == KeyEvent.VK_SPACE) { // 如果按下空格 就开始动
            if (failFlag) {
                // 重新开始
                failFlag = false;
                init();
            } else {
                startFlag = !startFlag; //取反
            }
            this.repaint();
        }
        // 小蛇移动
        switch (keyCode) {
            case KeyEvent.VK_UP:
                if (beforePress != null && !beforePress.equals("D")) {
                    direct = "U";
                    break;
                }
            case KeyEvent.VK_DOWN:
                if (beforePress != null && !beforePress.equals("U")) {
                    direct = "D";
                    break;
                }
            case KeyEvent.VK_LEFT:
                if (beforePress != null && !beforePress.equals("R")) {
                    direct = "L";
                    break;
                }
            case KeyEvent.VK_RIGHT:
                if (beforePress != null && !beforePress.equals("L")) {
                    direct = "R";
                    break;
                }
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {

    }
}
*************************
package com.day;


import com.day.pojo.GamePanel;

import javax.swing.*;

/**
 * main function
 */
public class DayApplication {
    public static void main(String[] args) {
        JFrame jFrame = new JFrame("这是JFrame窗口");
        // 游戏面板
        GamePanel gamePanel = new GamePanel();

        jFrame.add(gamePanel);
        jFrame.setSize(1000, 1000);
        jFrame.setResizable(false);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}