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Java applet错误……有什么问题？

2019-09-27 23:03:27 作者：互联网

Java applet代码

package M257Applet

import java.applet.*;

import javax.swing.*;

import java.awt.*;

public class HellowApplet extends JApplet {

    public  void init(){

        Container cp = getContentPane();
        JLabel lb = new JLabel("Hellowwwww");
        cp.add(lb);
    }

}

html文件

<html>
<head>
<title>Applet</title>
</head>
<body>
<APPLET CODE = HellowApplet.class  WIDTH =  400   HEIGHT = 400 >
</APPLET>
</body>
</html>

错误

Java Plug-in 1.6.0_22
Using JRE version 1.6.0_22-b04 Java HotSpot(TM) Client VM
User home directory = C:\Users\pc
----------------------------------------------------
c:   clear console window
f:   finalize objects on finalization queue
g:   garbage collect
h:   display this help message
l:   dump classloader list
m:   print memory usage
o:   trigger logging
q:   hide console
r:   reload policy configuration
s:   dump system and deployment properties
t:   dump thread list
v:   dump thread stack
x:   clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------


java.lang.NoClassDefFoundError: HellowApplet (wrong name: M257Applet/HellowApplet)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Exception: java.lang.NoClassDefFoundError: HellowApplet (wrong name: M257Applet/HellowApplet)

解决方法:

问题在于包装.您需要更改applet的代码属性,并根据放置HTML的位置,更改代码库属性.您必须将HellowApplet.class放在名为M257Applet的目录中(因为这是您提供的包),并且applet标记应如下所示：

<applet code="M257Applet.HellowApplet" ... ></applet>

为此,您的HTML必须与M257Applet位于同一目录中(不在M257Applet内).或者,您可以指定codebase属性.例如,使用以下目录结构：

somedir
  +-- hello.html
  +-- M257Applet
  |    +-- HellowApplet.class

小程序将工作.但是,如果你有

anotherdir
  +-- hello.html
  +-- somedir
  |   +-- M257Applet
  |   |    +-- HellowApplet.class

那么你必须像这样指定codebase属性：

<applet code="M257Applet.HellowApplet" codebase="somedir" ... ></applet>

因此,您应该让代码库指向包含您的包的目录,并且代码也必须包含您的包名.

编辑：
请注意,即使code =“HellowApplet.class”可行,指定applet的正确方法最后也没有“.class”.

标签：html,japplet,java,swing
来源： https://codeday.me/bug/20190927/1824989.html