Java高级教程：事件处理

Applet类从Container类继承了许多事件处理方法。Container类定义了几个方法，例如：processKeyEvent()和processMouseEvent()，用来处理特别类型的事件，还有一个捕获所有事件的方法叫做processEvent。

　

　为了响应一个事件，applet必须重写合适的事件处理方法。
 

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importjava.awt.event.MouseListener;

importjava.awt.event.MouseEvent;

importjava.applet.Applet;

importjava.awt.Graphics;

  

publicclass ExampleEventHandling extendsApplet

                             implementsMouseListener {

  

    StringBuffer strBuffer;

  

    publicvoid init() {

         addMouseListener(this);

         strBuffer = newStringBuffer();

        addItem("initializing the apple ");

    }

  

    publicvoid start() {

        addItem("starting the applet ");

    }

  

    publicvoid stop() {

        addItem("stopping the applet ");

    }

  

    publicvoid destroy() {

        addItem("unloading the applet");

    }

  

    voidaddItem(String word) {

        System.out.println(word);

        strBuffer.append(word);

        repaint();

    }

  

    publicvoid paint(Graphics g) {

         //Draw a Rectangle around the applet's display area.

        g.drawRect(0, 0,

                      getWidth() - 1,

                      getHeight() - 1);

  

         //display the string inside the rectangle.

        g.drawString(strBuffer.toString(), 10, 20);

    }

     

    publicvoid mouseEntered(MouseEvent event) {

    }

    publicvoid mouseExited(MouseEvent event) {

    }

    publicvoid mousePressed(MouseEvent event) {

    }

    publicvoid mouseReleased(MouseEvent event) {

    }

  

    publicvoid mouseClicked(MouseEvent event) {

         addItem("mouse clicked! ");

    }

}

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