13.4 Applet

1 一个简单的Applet

import java.awt.*;
import javax.swing.*;

/**
 1. @version 1.24 2015-06-12
 2. @author Cay Horstmann
 */
public class NotHelloWorld extends JApplet
{
   public void init()
   {
      EventQueue.invokeLater(() -> {
         JLabel label = new JLabel("Not a Hello, World applet",
               SwingConstants.CENTER);
         add(label);
      });
   }
}

1. 编译为class文件
2. 打包成JAR文件
3. 创建HTML文件，告诉浏览器装载这个文件和界面大小。

<applet class="applet/NotHelloWorld.class" archive="NotHelloWorld.jar" width="300" height="300">
</applet>

appletviewer NotHelloWorldApplet.html

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2 applet标签和它的属性

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3 使用参数想applet传递信息

<applet code="FontParamApplet.class" ...>
    <param name="font" value="Helvetica"/>
</applet>

public class FontParamApplet extends JApplet
{
    public void init()
    {
        String fontName = getParameter("font");
        . . .
    }
. . .
}

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4 接受图片和音频文件

Image cat = getImage(getDocumentBase(), "images/cat.gif");
AudioClip meow = getAudioClip(getDocumentBase(), "audio/meow.au");

play(getDocumentBase(), "audio/meow.au");

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5 Applet环境

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6 Applet间的交互

<applet code="Chart.class" width="100" height="100" name="Chart1">

Applet chart1 = getAppletContext().getApplet("Chart1");

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7 在浏览器中显示信息

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8 沙箱

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9 签名代码