Java 适配器类

17 Mar 2025 | 4 分钟阅读

Java 适配器类*提供了监听器接口的默认实现*。如果您继承适配器类，则无需强制提供监听器接口的所有方法的实现。因此，它节省了代码。

使用适配器类的优点

它有助于不相关的类协同工作。
它提供了以不同方式使用类的方法。
它增加了类的透明度。
它提供了一种在类中包含相关模式的方法。
它为开发应用程序提供了一个可插拔的工具包。
它增加了类的可重用性。

适配器类位于 java.awt.event, java.awt.dnd 和 javax.swing.event 包中。适配器类及其对应的侦听器接口如下所示。

java.awt.event 适配器类

适配器类	监听器接口
WindowAdapter	WindowListener
KeyAdapter	KeyListener
MouseAdapter	MouseListener
MouseMotionAdapter	MouseMotionListener
FocusAdapter	FocusListener
ComponentAdapter	ComponentListener
ContainerAdapter	ContainerListener
HierarchyBoundsAdapter	HierarchyBoundsListener

java.awt.dnd 适配器类

适配器类	监听器接口
DragSourceAdapter	DragSourceListener
DragTargetAdapter	DragTargetListener

javax.swing.event 适配器类

适配器类	监听器接口
MouseInputAdapter	MouseInputListener
InternalFrameAdapter	InternalFrameListener

Java WindowAdapter 示例

在以下示例中，我们正在实现 AWT 的 WindowAdapter 类及其方法 windowClosing() 来关闭框架窗口。

AdapterExample.java

// importing the necessary libraries
import java.awt.*;  
import java.awt.event.*;  

public class AdapterExample {
// object of Frame  
    Frame f;  
// class constructor
    AdapterExample() {  
// creating a frame with the title
        f = new Frame ("Window Adapter");  
// adding the WindowListener to the frame
// overriding the windowClosing() method 
        f.addWindowListener (new WindowAdapter() {  
            public void windowClosing (WindowEvent e) {  
                f.dispose();  
            }  
        });  
         // setting the size, layout and 
        f.setSize (400, 400);  
        f.setLayout (null);  
        f.setVisible (true);  
    }  

// main method
public static void main(String[] args) {  
    new AdapterExample();  
}  
}  

输出

Java MouseAdapter 示例

在下面的示例中，我们正在实现 MouseAdapter 类。 MouseListener 接口被添加到框架中以监听框架中的鼠标事件。

MouseAdapterExample.java

// importing the necessary libraries
import java.awt.*;  
import java.awt.event.*;  

// class which inherits the MouseAdapter class
public class MouseAdapterExample extends MouseAdapter {  
// object of Frame class
    Frame f;  
// class constructor
    MouseAdapterExample() {  
// creating the frame with the title
        f = new Frame ("Mouse Adapter");  
// adding MouseListener to the Frame
        f.addMouseListener(this);  
   // setting the size, layout and visibility of the frame
        f.setSize (300, 300);  
        f.setLayout (null);  
        f.setVisible (true);  
    }  
// overriding the mouseClicked() method of the MouseAdapter class
    public void mouseClicked (MouseEvent e) {  
// creating the Graphics object and fetching them from the Frame object using getGraphics() method
        Graphics g = f.getGraphics();  
// setting the color of graphics object
        g.setColor (Color.BLUE);  
// setting the shape of graphics object
        g.fillOval (e.getX(), e.getY(), 30, 30);  
    }  
  // main method
public static void main(String[] args) {  
    new MouseAdapterExample();  
}  
}  

输出

Java MouseMotionAdapter 示例

在以下示例中，我们正在实现 MouseMotionAdapter 类及其不同的方法，以侦听 Frame 窗口中的鼠标移动事件。

MouseMotionAdapterExample.java

// importing the necessary libraries
import java.awt.*;  
import java.awt.event.*;  
// class which inherits the MouseMotionAdapter class
public class MouseMotionAdapterExample extends MouseMotionAdapter {   
// object of Frame class
    Frame f;  
// class constructor
    MouseMotionAdapterExample() {  
// creating the frame with the title
        f = new Frame ("Mouse Motion Adapter");  
// adding MouseMotionListener to the Frame
        f.addMouseMotionListener (this);  
 // setting the size, layout and visibility of the frame
        f.setSize (300, 300);  
        f.setLayout (null);  
        f.setVisible (true);  
    }  
// overriding the mouseDragged() method 
public void mouseDragged (MouseEvent e) {  
// creating the Graphics object and fetching them from the Frame object using getGraphics() method
    Graphics g = f.getGraphics();  
// setting the color of graphics object
    g.setColor (Color.ORANGE);  
// setting the shape of graphics object
    g.fillOval (e.getX(), e.getY(), 20, 20);  
}  
public static void main(String[] args) {  
    new MouseMotionAdapterExample();  
}  
}  

输出

Java KeyAdapter 示例

在以下示例中，我们正在实现 KeyAdapter 类及其方法。

KeyAdapterExample.java

// importing the necessary libraries
import java.awt.*;  
import java.awt.event.*;  
// class which inherits the KeyAdapter class
public class KeyAdapterExample extends KeyAdapter {  
// creating objects of Label, TextArea and Frame
    Label l;  
    TextArea area;  
    Frame f;  
// class constructor
    KeyAdapterExample() {  
// creating the Frame with title
        f = new Frame ("Key Adapter");  
// creating the Label
        l = new Label();  
// setting the location of label 
        l.setBounds (20, 50, 200, 20);  
// creating the text area
        area = new TextArea();
// setting the location of text area  
        area.setBounds (20, 80, 300, 300);  
// adding KeyListener to text area
        area.addKeyListener(this);  
 // adding the label and text area to frame
        f.add(l);
f.add(area);  
// setting the size, layout and visibility of frame
        f.setSize (400, 400);  
        f.setLayout (null);  
        f.setVisible (true);  
    }  
// overriding the keyReleased() method 
    public void keyReleased (KeyEvent e) {  
// creating the String object to get the text fromTextArea 
        String text = area.getText();  
// splitting the String into words
        String words[] = text.split ("\\s");  
// setting the label text to print the number of words and characters of given string
        l.setText ("Words: " + words.length + " Characters:" + text.length());  
    }  
  // main method
    public static void main(String[] args) {  
        new KeyAdapterExample();  
    }  
}  

输出

下一个主题如何在 Java 中关闭 AWT 窗口

Java 适配器类

使用适配器类的优点

java.awt.event 适配器类

java.awt.dnd 适配器类

javax.swing.event 适配器类

Java WindowAdapter 示例

Java MouseAdapter 示例

Java MouseMotionAdapter 示例

Java KeyAdapter 示例

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Java 适配器类

使用适配器类的优点

java.awt.event 适配器类

java.awt.dnd 适配器类

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Java WindowAdapter 示例

Java MouseAdapter 示例

Java MouseMotionAdapter 示例

Java KeyAdapter 示例

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