Java 中的 MouseListener 和 MouseMotionListener 有什么区别?

awtjavaobject oriented programmingprogrammingswing

我们可以在鼠标稳定时实现 MouseListener 接口来处理鼠标事件，而在鼠标移动时处理鼠标事件，我们可以实现 MouseMotionListener 接口。

鼠标监听器

当我们在源对象上按下、释放或单击(按下后释放)鼠标按钮(左键或右键)或将鼠标指针定位在(进入)和远离(退出)源对象时，将触发 MouseEvent。

MouseListener 接口声明了以下五个抽象方法

语法

public void mouseClicked(MouseEvent evt)
public void mousePressed(MouseEvent evt)
public void mouseReleased(MouseEvent evt)
public void mouseEntered(MouseEvent evt)
public void mouseExited(MouseEvent evt)

示例

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MouseListenerTest extends JFrame implements MouseListener {
   private JTextField tfMouseX, tfMouseY;
   public MouseListenerTest() {
      setLayout(new FlowLayout());
      add(new Label("X-Click: "));
      tfMouseX = new JTextField(10);
      tfMouseX.setEditable(false);
      add(tfMouseX);
      add(new Label("Y-Click: "));
      tfMouseY = new JTextField(10);
      tfMouseY.setEditable(false);
      add(tfMouseY);
      addMouseListener(this);
      setTitle("MouseListener Test");
      setLocationRelativeTo(null);
      setSize(350, 100);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setVisible(true);
   }
   public static void main(String[] args) {
      new MouseListenerTest();
   }
   @Override
   public void mouseClicked(MouseEvent evt) {
      tfMouseX.setText(evt.getX() + "");
      tfMouseY.setText(evt.getY() + "");
   }
   // Need to provide an empty body to compile.
   @Override public void mousePressed(MouseEvent evt) { }
   @Override public void mouseReleased(MouseEvent evt) { }
   @Override public void mouseEntered(MouseEvent evt) { }
   @Override public void mouseExited(MouseEvent evt) { }
}

输出

MouseMotionListener

当我们移动和拖动源对象上的鼠标指针时，也会触发MouseEvent。但我们需要使用MouseMotionListener来处理鼠标移动和鼠标拖动。

MouseMotionListener接口声明了以下两个抽象方法

语法

public void mouseDragged(MouseEvent e)
public void mouseMoved(MouseEvent e)

示例

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MouseMotionListenerTest extends JFrame implements MouseListener, MouseMotionListener {
   private JTextField tfMouseClickX, tfMouseClickY;
   private JTextField tfMousePositionX, tfMousePositionY;
   public MouseMotionListenerTest() {
      setLayout(new FlowLayout());
      add(new Label("X-Click: "));
      tfMouseClickX = new JTextField(10);
      tfMouseClickX.setEditable(false);
      add(tfMouseClickX);
      add(new Label("Y-Click: "));
      tfMouseClickY = new JTextField(10);
      tfMouseClickY.setEditable(false);
      add(tfMouseClickY);
      add(new JLabel("X-Position: "));
      tfMousePositionX = new JTextField(10);
      tfMousePositionX.setEditable(false);
      add(tfMousePositionX);
      add(new JLabel("Y-Position: "));
      tfMousePositionY = new JTextField(10);
      tfMousePositionY.setEditable(false);
      add(tfMousePositionY);
      addMouseListener(this);
      addMouseMotionListener(this);
      setTitle("MouseMotionListener Test");
      setSize(400, 120);
      setLocationRelativeTo(null);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setVisible(true);
   }
   public static void main(String[] args) {
      new MouseMotionListenerTest();
   }
   @Override
   public void mouseClicked(MouseEvent evt) {
      tfMouseClickX.setText(evt.getX() + "");
      tfMouseClickY.setText(evt.getY() + "");
   }
   // 需要提供一个空的主体以便编译
   @Override public void mousePressed(MouseEvent evt) { }
   @Override public void mouseReleased(MouseEvent evt) { }
   @Override public void mouseEntered(MouseEvent evt) { }
   @Override public void mouseExited(MouseEvent evt) { }
   @Override
   public void mouseMoved(MouseEvent evt) {
      tfMousePositionX.setText(evt.getX() + "");
      tfMousePositionY.setText(evt.getY() + "");
   }
   // 需要提供一个空主体才能进行编译
   @Override public void mouseDragged(MouseEvent evt) { }
}