Java开发网 - JMF的摄像头Applet无法运行的问题？

Topic: JMF的摄像头Applet无法运行的问题？

1.JMF的摄像头Applet无法运行的问题？

Posted by: yanqlv
Posted on: 2005-09-16 22:39

我做了一个基于JMF的摄像头程序，
在Application的时候运行很好，
可是一改成applet,
就在这个地方出错：(加******的地方），
用过的高手请帮忙看一下是什么问题，
我已经排除了由于applet 的安全问题，
我把安全设置为AllPermission
因为/* test applet security */
/* test end */之间的部分能够正常对本地文件进行操作。

.....
String str1 = "vfw:Logitech USB Video Camera:0";
String str2 = "vfw:Microsoft WDM Image Capture (Win32):0";
di = CaptureDeviceManager.getDevice(str2);
/* test applet security */
try{
java.io.File existDir = new java.io.File("e:/empty");
java.io.File newFile = new java.io.File("e:/testforjava");
System.out.println("existDir.delete()="+existDir.delete());
System.out.println("newFile.createNewFile()="+newFile.createNewFile());

}catch(Exception e){
System.out.println("file delete exception:"+e);
e.printStackTrace();
}
/* test end */
System.out.println("di="+di);///**************** di=null**************
ml = di.getLocator();///**************** exception throw here**************
try
{
player = Manager.createRealizedPlayer(ml);
player.start();
Component comp;
if ((comp = player.getVisualComponent()) != null)
{
add(comp, BorderLayout.NORTH);
}
Panel panel1 = new Panel(new BorderLayout());
panel1.add(capture, BorderLayout.NORTH);
panel1.add(new Label("请输入对应的文件名:"), BorderLayout.WEST);
panel1.add(num, BorderLayout.CENTER);
panel1.add(save, BorderLayout.SOUTH);
add(panel1, BorderLayout.CENTER);
add(imgpanel, BorderLayout.SOUTH);
}
catch (Exception e)
{
e.printStackTrace();
}
}
.....

错误提示：
di=null

java.lang.NullPointerException

  at CamApplet.<init>(CamApplet.java:96)

  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

  at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)

  at java.lang.reflect.Constructor.newInstance(Unknown Source)

  at java.lang.Class.newInstance0(Unknown Source)

  at java.lang.Class.newInstance(Unknown Source)

  at sun.applet.AppletPanel.createApplet(Unknown Source)

  at sun.plugin.AppletViewer.createApplet(Unknown Source)

  at sun.applet.AppletPanel.runLoader(Unknown Source)

  at sun.applet.AppletPanel.run(Unknown Source)

  at java.lang.Thread.run(Unknown Source)

??