1：变换背景（案例）

深碍√TFBOYSˉ_ 2022-03-25 06:40 43阅读 0赞

##### 需求：根据按钮点击变换下边区域的颜色背景 #####

## ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L09jdG9wdXMyMQ_size_16_color_FFFFFF_t_70] ##

##### 知识点：继承、接口、布局 #####

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package demo1;
    
    
    import java.awt.BorderLayout;
    import java.awt.Color;
    import java.awt.FlowLayout;
    import java.awt.Font;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    
    import javax.swing.*;
    
    public class EventFrame extends JFrame implements ActionListener {
        private JButton btnRed = new JButton("红色");
        private JButton btnGreen = new JButton("绿色");
        private JButton btnBlue = new JButton("蓝色");
        private JTextField jTextField = new JTextField();
        private JPanel p = new JPanel();
    
        public EventFrame() {
            btnRed.setFont(new Font("", Font.BOLD, 24));
            btnGreen.setFont(new Font("", Font.BOLD, 24));
            btnBlue.setFont(new Font("", Font.BOLD, 24));
            p.setLayout(new FlowLayout());
            p.add(btnRed);
            p.add(btnGreen);
            p.add(btnBlue);
            btnRed.addActionListener(this);   //使用this来传递当前对象引用
            btnGreen.addActionListener(this);
            btnBlue.addActionListener(this);
            jTextField.setSize(300, 300);
            getContentPane().setLayout(new BorderLayout());
            getContentPane().add(jTextField, BorderLayout.CENTER);
            getContentPane().add(p, BorderLayout.NORTH);
            setSize(400, 300);
            setVisible(true);
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        }
    
        @Override
        public void actionPerformed(ActionEvent e) {
            JButton obj = (JButton) e.getSource();   //使用getSource获取当前事件源，然后强转为按钮对象
            if (obj == btnRed) {
                jTextField.setBackground(Color.red);
            } else if (obj == btnGreen) {
                jTextField.setBackground(Color.green);
            } else {
                jTextField.setBackground(Color.blue);
            }
        }
    }

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##### 程序入口 #####

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package demo1;
    
    /**
     * Date: 2019/1/18 0018
     **/
    public class Main {
        public static void main(String[] args) {
            new EventFrame();
    
        }
    }

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##### 方法参考 #####

##### 1：接口ActionListener的源码 #####

public interface ActionListener extends EventListener {
    
        /**
         * Invoked when an action occurs.
         */
        public void actionPerformed(ActionEvent e);
    
    }

##### 2：Swing布局(参考下一节) #####

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##### 3：getContentPane()方法 #####

getContentPane
    public Container getContentPane()返回此框架的 contentPane对象。 
    Specified by: 
    getContentPane在接口 RootPaneContainer 
    结果 
    contentPane财产 
    另请参见： 
    setContentPane(java.awt.Container) ， RootPaneContainer.getContentPane()

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