怎么判断控件是否安装了呢
<OBJECT
classid   =   "clsid:8AD9C840-044E-11D1-B3E9-00805F499D93 "
codebase   =   "http://210.222.48.75/jvm_setup.exe "
WIDTH   =   "1024 "   HEIGHT   =   "768 "   >
<PARAM   NAME   =   CODE   VALUE   =   "testauto.Applet1.class "   >
<PARAM   NAME   =   CODEBASE   VALUE   =   ". "   >
<PARAM   NAME   =   "type "   VALUE   =   "application/x-java-applet;version=1.4 ">
<PARAM   NAME   =   "scriptable "   VALUE   =   "false ">
<PARAM   NAME   =   "projectId "   VALUE= " <%=theForm.getProjectId().toString()%> "   >
<PARAM   NAME   =   "userId "   VALUE= " <%=userId%> "   >
<PARAM   NAME   =   "logLevel "   VALUE= "INFO "   >
<COMMENT>
<EMBED
type= "application/x-java-applet;jpi-version=1.4.1 "
CODE= "testauto.Applet1.class "
CODEBASE= ". "
WIDTH= "1024 "
HEIGHT= "768 "
projectId= " <%=theForm.getProjectId().toString()%> "
userId= " <%=userId%> "
logLevel= "INFO "
scriptable=false
pluginspage= "http://java.sun.com/j2se/1.4.1/download.html ">
<NOEMBED>
Could   not   find   a   plugin   supported   by   your   browser.   Please   download   Sun 's   Java   Plugin   1.4.1
</noembed>
</EMBED>
</COMMENT>
</OBJECT>

这个是判断是否安装了jvm的，是吧？
由于这个JVM比较大，所以下载的时间就比较长，所以我想在他下载的时候给个提示，叫他等待，如果安装了JVM的就不会下载了的，这个提示呢也不会显示

所以怎么判断这个提示什么时候显示，什么时候不显示啊，代码怎么写啊，我是不懂网页的，我只是做applet，如果别人机器上没有JVM，就给他下载安装

------解决方案--------------------
<applet width=712 height=482>
<PARAM NAME = 。。。。
<PARAM NAME = 。。。。
<PARAM NAME = 。。。。
<span class= "cDGray "> 如果您无法看到,请点此下载插件并安装,然后刷新此页面即可! </span>
</applet>