GUI的基本使用方式之代码实例（一）

作者：叁念

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1.如何创建GUI（由小组件进行演示讲解）

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

public class Demo01 {
    public static void main(String[] args) {
        // 1.创建jFrame
        JFrame jFrame = new JFrame();
        /** 下面这一行代码的效果是：在用户关闭窗口是把程序结束掉 */
        jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        // 2.创建一个组件（widget）—— 按钮
        JButton jButton = new JButton("按钮名称");
        // 3.将组件（按钮）添加到到jFrame(里面的Pane)上
        jFrame.getContentPane().add(jButton);
        // 4.设置尺寸并 显示
        jFrame.setSize(300, 300);
        jFrame.setVisible(true);
    }
}

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运行后效果展示 ：

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2.实现监听事件

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

public class Demo02 implements ActionListener {// 1.实现时间监听 需要实现该接口（事件只会通知所有实现ActionListener接口的类）
    JButton jButton;

    public static void main(String[] args) {
        Demo02 gui = new Demo02();
        gui.go();
    }

    public void go() {
        JFrame jFrame = new JFrame();
        jButton = new JButton("按钮名称");
        // 3.为按钮进行注册
        jButton.addActionListener(this);

        jFrame.getContentPane().add(jButton);
        jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jFrame.setSize(300, 300);
        jFrame.setVisible(true);
    }

    // 2.实现接口后需要重写该方法（你希望要执行的事件）
    @Override
    public void actionPerformed(ActionEvent e) {
        //4.按钮需要做的操作
        jButton.setText("事件监听，有用户点击");
    }
}

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点击后效果展示 ：

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2.GUI简单图形绘制案例

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

public class Demo03{
    public static void main(String[] args) {
        JFrame jFrame = new JFrame();
        /**绘制一个2D图形(圆形)*/
//      jFrame.add(new JPanel() {
//          @Override
//          protected void paintComponent(Graphics g) {
//              g.setColor(Color.red);
//              g.fillOval(70, 70, 100, 100);
//          }
//      });

        /**绘制一个渐变色圆,拖动窗口可变色*/
        jFrame.add(new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                Graphics2D g2d = (Graphics2D) g;

                //1.获取随机RGB三个参数，并制作颜色
                int red  = (int)(Math.random()*255);
                int green  = (int)(Math.random()*255);
                int blue  = (int)(Math.random()*255);
                Color startColor = new Color(red, green, blue);

                //2.再次获取随机RGB三个参数，并制作颜色
                red  = (int)(Math.random()*255);
                green  = (int)(Math.random()*255);
                blue  = (int)(Math.random()*255);
                Color endColor = new Color(red, green, blue);

                //3.制作渐变色
                GradientPaint gradientPaint = new GradientPaint(70, 70, startColor, 150,150,endColor);
                g2d.setPaint(gradientPaint);
                //4.画圆
                g2d.fillOval(70, 70, 100, 100);
            }
        });

        jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jFrame.setSize(300, 300);
        jFrame.setVisible(true);
    }


}

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效果展示 ：

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3.GUI的布局

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

public class Demo04 {
    JFrame jFrame;
    JLabel jLabel;

    public static void main(String[] args) {
        Demo04 event = new Demo04();
        event.go();
    }

    public void go() {
        jFrame = new JFrame();

        //1.创建若干组件
        JButton colorButton = new JButton("改变颜色");
        JButton lableButton = new JButton("改变lable文字");
        jLabel = new JLabel("这是一个JLabel");

        //2.为Button组件进行监听注册
        colorButton.addActionListener(new ColorListenner());
        lableButton.addActionListener(new LabelListenner());

        //3.将组件添加到jFrame上，并布局显示
        jFrame.add(BorderLayout.WEST,jLabel);
        jFrame.add(BorderLayout.EAST,lableButton);
        jFrame.add(BorderLayout.SOUTH, colorButton);
        jFrame.add(BorderLayout.CENTER, new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                Graphics2D g2d = (Graphics2D) g;

                int red = (int) (Math.random() * 255);
                int green = (int) (Math.random() * 255);
                int blue = (int) (Math.random() * 255);
                Color startColor = new Color(red, green, blue);

                red = (int) (Math.random() * 255);
                green = (int) (Math.random() * 255);
                blue = (int) (Math.random() * 255);
                Color endColor = new Color(red, green, blue);

                GradientPaint gradientPaint = new GradientPaint(70, 70, startColor, 150, 150, endColor);
                g2d.setPaint(gradientPaint);
                g2d.fillOval(70, 70, 100, 100);
            }
        });

        jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jFrame.setSize(500,500);
        jFrame.setVisible(true);
    }
    /**
     *内部类  LabelListenner,按钮lableButton的事件
     */
    class LabelListenner implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            jLabel.setText("奥，点击！！！");
        }

    }
    /**
     *内部类  ColorListenner,按钮colorButton的事件
     */
    class ColorListenner implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            jFrame.repaint();
        }

    }
}

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效果展示 ：