怎样自动检测用户有没有安装realplayer的插件，并能自动安装它？

 1<object classid="clsid:CFCDAA03-8BE4-11cf-B84B-0020AFBBCCFA" height="240" id="RVOCX" onerror="return false;" style="LEFT: 0px; TOP: 0px" viewastext="" width="320">
 2<param name="_ExtentX" value="8467"/>
 3<param name="_ExtentY" value="6350"/>
 4<param name="AUTOSTART" value="-1"/>
 5<param name="SHUFFLE" value="0"/>
 6<param name="PREFETCH" value="0"/>
 7<param name="NOLABELS" value="-1"/>
 8<param name="SRC" value="http://192.168.0.7:8000/plugin.rpm"/>
 9<param name="CONTROLS" value="ImageWindow"/>
10<param name="CONSOLE" value="one"/>
11<param name="LOOP" value="0"/>
12<param name="NUMLOOP" value="0"/>
13<param name="CENTER" value="0"/>
14<param name="MAINTAINASPECT" value="0"/>
15<param name="BACKGROUNDCOLOR" value="#000000"/>
16<embed autostart="true" console="one" controls="ImageWindow" height="240" nojava="true" src="plugin.rpm" width="320"/></object>

 1<script language="JavaScript">   
 2var RealMode=0;   
 3var RealPlayer5=0;   
 4var RealPlayer4=0;   
 5var RealPlayerG2=0;   
 6  
 7if (navigator.userAgent.indexOf("MSIE")<0 )   
 8{   
 9numPlugins = navigator.plugins.length;   
10for (i = 0; i < numPlugins; i++)   
11{   
12plugin = navigator.plugins[i];   
13if (plugin.name.substring(0,10)=="RealPlayer")   
14{   
15RealMode=1;   
16}   
17}   
18}   
19  
20document.write('<SCRIPT LANGUAGE=VBScript\> \n');   
21document.write('on error resume next \n');   
22document.write('RealPlayerG2 = (NOT IsNull(CreateObject("rmocx.RealPlayer G2 Control")))\n');   
23document.write('RealPlayer5 = (NOT IsNull(CreateObject("RealPlayer.RealPlayer(tm) ActiveX Control (32-bit)")))\n');   
24document.write('RealPlayer4 = (NOT IsNull(CreateObject("RealVideo.RealVideo(tm) ActiveX Control (32-bit)")))\n');   
25document.write('</SCRIPT\> \n');   
26  
27  
28if (RealMode ¦ ¦ RealPlayerG2 ¦ ¦ RealPlayer5 ¦ ¦ RealPlayer4)   
29{   
30alert("RealPlayer plug-in is installed.");   
31}   
32else   
33{   
34alert("RealPlayer plug-in is not installed.");   
35}   
36</script>

1<object classid="clsid:CFCDAA03-8BE4-11cf-B84B-0020AFBBCCFA" height="240" id="RVOCX" onerror="alert('你还没装realplay呢？');return false;" style="LEFT: 0px; TOP: 0px" viewastext="" width="320">   
2\---------------------------------------------------------------   
3  
4<object classid="clsid:CFCDAA03-8BE4-11cf-B84B-0020AFBBCCFA" onerror='alert("没装RealPlayer")'></object></object>