JApplet未运行：＆lt;找不到主要课程＆gt;

Question

当DrawOvalInputs.html运行并调用DrawOvalInputs的类文件时，我的JApplet产生错误。到目前为止，我只能将它作为一个实际的应用程序工作（这就是为什么主要在块引用中）。

我的这个程序的目标是能够运行一个.html文件来启动JSPlet，在Java控制台上使用中等安全设置，但不管我做了什么，它只是赢得了＃t功能

在来到这里之前，我已经浏览了很多页面并进行了搜索。遗憾的是，我无法想象这个JApplet，所以如果有人能指引我朝着正确的方向前进，我将非常感激！

我的代码如下：

DrawOvalInputs.java

package drawovalapplet;

import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.Graphics;
import javax.swing.JApplet;
import javax.swing.JOptionPane;

/**
 * This applet inputs a number of values, and then computes the size of
 * an oval with those given values. 
 *
 * @author  [Redacted]
 * @version 2014-05-02, [Redacted]
 */
public class DrawOvalInputs extends JApplet
{
    private static int x;               //left edge of the oval
    private static int y;               //top edge of the oval
    private static int width;           //width of oval
    private static int height;          //height of oval
    private static int windowWidth;     //Holds necessary width of window.
    private static int windowHeight;    //Holds necessary height of window.
    private static int windowBox;       //Holds box form of window.


@Override
public void init()
{    
    try 
    {
        /** Collect the input values. */    
        Input.inputAll();

        /** creates dimensions for box */
        windowWidth = width + x + 50;
        windowHeight = height + y + 50;

        /** 
         * If... else... function to gather data to create
         * a fitting box for the oval
         */
        if(windowWidth > windowHeight)
            windowBox = windowWidth;
        else
            windowBox = windowHeight;

    } catch (Input.CanceledException ex) {
        System.exit(1);
    }
} 

@Override
public void paint(Graphics g)
{
    super.paint(g);      
    g.drawOval(x, y, width, height);
} // end method pain


/**
 * Main entry point.
 * <p> Execute:
 * <pre>java drawovalapplet.DrawOvalInputs</pre>
 *
 * @param args not used.
 */
/*public static void main(String args[])
{
Frame frame = new Frame("DrawOvalInputs");
DrawOvalInputs drawOval = new DrawOvalInputs();
drawOval.init();
drawOval.start();
frame.add(drawOval);
frame.setSize(drawOval.windowBox, drawOval.windowBox);
frame.setVisible(true);
}*/

//------------------------------- Nested Classes --------------------------------

/**
 * Enumeration of the name and value of the input values.
 */
private enum Input
{
/**
 * Message for the entering the x coordinate.
 */
XVALUE("Enter the argument for the x coordinate of the upper left corner of the oval to be drawn:"),

/**
 * Message for the entering the y coordinate.
 */
YVALUE("Enter the argument for the y coordinate of the upper left corner of the oval to be drawn:"),

/**
 * Message for entering the width.
 */
WIDTHVALUE("Enter the desired width of the oval to be drawn:"),

/**
 * Message for entering the height.
 */
HEIGHTVALUE("Enter the desired height of the oval:");

/**
 * String to use in messages (from the constructor).
 */
protected String invitation;

/**
 * String to use for error messages.
 */
protected String error = "Not an integer value--please re-enter:";

/**
 * Value of this {@literal <variable>}.
 */
protected int value;

/**
 * @param label string to use in messages
 */
Input(String invitation)
{
    this.invitation = invitation;
}

public static void inputAll() throws CanceledException
{
    /* Decide which input value is currently being used. */
    int count = 0; 

    /* Collect the input numbers. */
    for(Input input : Input.values())
    {
        /* Set up the invitation to enter each number. */
        String message = input.invitation;

        /* Loop until the user inputs an acceptably formatted number. */
        while(true)                         // repetition environment
        {
            String response;
            /* Null return from the JOptionPane indicates CANCEL was pressed. */
            if( (response = JOptionPane.showInputDialog(message)) == null)
                throw new CanceledException();
            message = input.error;              // just in case
            try
            {
                input.value = Integer.parseInt(response);
                break;                          // success in acquiring value
            }
            catch(NumberFormatException nfe) {}// ignore all, and try again
        }
        count++;
        if(count == 1)
            x = input.value;
        else if(count == 2)
            y = input.value;
        else if (count == 3)
            width = input.value;
        else if (count == 4)
            height = input.value;
        else
            System.out.println("Error. Revise.");   
    }
}

@SuppressWarnings("serial")
public static class CanceledException extends Exception {}
}
}

DrawOvalInputs.html 我使用DrawOvalInputs.java和下面的那个以及.class来运行它。

<html>
  <body>
      <applet code=drawovalapplet.DrawOvalInputs.java width=400 height=400>
      </applet>
  </body>
</html>

谢谢！

Answer 1

你必须用正确的路径调用它

如果你的路径是

DrawOvalApplet\build\classes\drawovalapplet\DrawOvalInputs.class

你的.html在

DrawOvalApplet\build\DrawOvalInputs.html

称之为

 ...
      <applet code=classes.drawovalapplet.DrawOvalInputs.class width=400 height=400>
      </applet>
 ...

好多了你的.html就在

中

DrawOvalApplet\build\classes\DrawOvalInputs.html

称之为

 ...
      <applet code=drawovalapplet.DrawOvalInputs.class width=400 height=400>
      </applet>
 ...

结果：

小程序正在运行

您可以致电htmlconverter并让它为您执行

java -jar htmlconverter.jar -gui

结果DrawOvalInputs.html

<html>
  <body>
      <!--"CONVERTED_APPLET"-->
<!-- HTML CONVERTER -->
<object
    classid = "clsid:CAFEEFAC-0017-0000-0051-ABCDEFFEDCBA"
    codebase = "http://java.sun.com/update/1.7.0/jinstall-7u51-windows-i586.cab#Version=7,0,510,13"
    WIDTH = 400 HEIGHT = 400 >
    <PARAM NAME = CODE VALUE = drawovalapplet.DrawOvalInputs.class >
    <param name = "type" value = "application/x-java-applet;jpi-version=1.7.0_51">
    <param name = "scriptable" value = "false">

    <comment>
    <embed
            type = "application/x-java-applet;jpi-version=1.7.0_51" \
            CODE = drawovalapplet.DrawOvalInputs.class \
            WIDTH = 400 \
            HEIGHT = 400
        scriptable = false
        pluginspage = "http://java.sun.com/products/plugin/index.html#download">
        <noembed>

            </noembed>
    </embed>
    </comment>
</object>

<!--
<APPLET CODE = drawovalapplet.DrawOvalInputs.class WIDTH = 400 HEIGHT = 400>


</APPLET>
-->
<!--"END_CONVERTED_APPLET"-->

  </body>
</html>

Answer 2

使用类文件和实际文件路径和名称。例如：

 <applet code=DrawOvalInputs.class width=400 height=400>
  </applet>

如果类文件与HTML文件位于同一文件夹中。