网页如何检查浏览器是否安装flash插件

如果页面需要加载flash插件并且需要提示用户flash下载，这里有个官方很好的js文件只要引用就可以实现

//v1.7
// Flash Player Version Detection
// Detect Client Browser type
// Copyright 2005-2007 Adobe Systems Incorporated.  All rights reserved.
var isIE  = (navigator.appVersion.indexOf("MSIE") != -1) ? true : false;
var isWin = (navigator.appVersion.toLowerCase().indexOf("win") != -1) ? true : false;
var isOpera = (navigator.userAgent.indexOf("Opera") != -1) ? true : false;

function ControlVersion()
{
    var version;
    var axo;
    var e;

    // NOTE : new ActiveXObject(strFoo) throws an exception if strFoo isn't in the registry

    try {
        // version will be set for 7.X or greater players
        axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash.7");
        version = axo.GetVariable("$version");
    } catch (e) {
    }

    if (!version)
    {
        try {
            // version will be set for 6.X players only
            axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash.6");
            
            // installed player is some revision of 6.0
            // GetVariable("$version") crashes for versions 6.0.22 through 6.0.29,
            // so we have to be careful. 
            
            // default to the first public version
            version = "WIN 6,0,21,0";

            // throws if AllowScripAccess does not exist (introduced in 6.0r47)        
            axo.AllowScriptAccess = "always";

            // safe to call for 6.0r47 or greater
            version = axo.GetVariable("$version");

        } catch (e) {
        }
    }

    if (!version)
    {
        try {
            // version will be set for 4.X or 5.X player
            axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash.3");
            version = axo.GetVariable("$version");
        } catch (e) {
        }
    }

    if (!version)
    {
        try {
            // version will be set for 3.X player
            axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash.3");
            version = "WIN 3,0,18,0";
        } catch (e) {
        }
    }

    if (!version)
    {
        try {
            // version will be set for 2.X player
            axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash");
            version = "WIN 2,0,0,11";
        } catch (e) {
            version = -1;
        }
    }
    
    return version;
}

// JavaScript helper required to detect Flash Player PlugIn version information
function GetSwfVer(){
    // NS/Opera version >= 3 check for Flash plugin in plugin array
    var flashVer = -1;
    
    if (navigator.plugins != null && navigator.plugins.length > 0) {
        if (navigator.plugins["Shockwave Flash 2.0"] || navigator.plugins["Shockwave Flash"]) {
            var swVer2 = navigator.plugins["Shockwave Flash 2.0"] ? " 2.0" : "";
            var flashDescription = navigator.plugins["Shockwave Flash" + swVer2].description;
            var descArray = flashDescription.split(" ");
            var tempArrayMajor = descArray[2].split(".");            
            var versionMajor = tempArrayMajor[0];
            var versionMinor = tempArrayMajor[1];
            var versionRevision = descArray[3];
            if (versionRevision == "") {
                versionRevision = descArray[4];
            }
            if (versionRevision[0] == "d") {
                versionRevision = versionRevision.substring(1);
            } else if (versionRevision[0] == "r") {
                versionRevision = versionRevision.substring(1);
                if (versionRevision.indexOf("d") > 0) {
                    versionRevision = versionRevision.substring(0, versionRevision.indexOf("d"));
                }
            }
            var flashVer = versionMajor + "." + versionMinor + "." + versionRevision;
        }
    }
    // MSN/WebTV 2.6 supports Flash 4
    else if (navigator.userAgent.toLowerCase().indexOf("webtv/2.6") != -1) flashVer = 4;
    // WebTV 2.5 supports Flash 3
    else if (navigator.userAgent.toLowerCase().indexOf("webtv/2.5") != -1) flashVer = 3;
    // older WebTV supports Flash 2
    else if (navigator.userAgent.toLowerCase().indexOf("webtv") != -1) flashVer = 2;
    else if ( isIE && isWin && !isOpera ) {
        flashVer = ControlVersion();
    }    
    return flashVer;
}

// When called with reqMajorVer, reqMinorVer, reqRevision returns true if that version or greater is available
function DetectFlashVer(reqMajorVer, reqMinorVer, reqRevision)
{
    versionStr = GetSwfVer();
    if (versionStr == -1 ) {
        return false;
    } else if (versionStr != 0) {
        if(isIE && isWin && !isOpera) {
            // Given "WIN 2,0,0,11"
            tempArray         = versionStr.split(" ");     // ["WIN", "2,0,0,11"]
            tempString        = tempArray[1];            // "2,0,0,11"
            versionArray      = tempString.split(",");    // ['2', '0', '0', '11']
        } else {
            versionArray      = versionStr.split(".");
        }
        var versionMajor      = versionArray[0];
        var versionMinor      = versionArray[1];
        var versionRevision   = versionArray[2];

            // is the major.revision >= requested major.revision AND the minor version >= requested minor
        if (versionMajor > parseFloat(reqMajorVer)) {
            return true;
        } else if (versionMajor == parseFloat(reqMajorVer)) {
            if (versionMinor > parseFloat(reqMinorVer))
                return true;
            else if (versionMinor == parseFloat(reqMinorVer)) {
                if (versionRevision >= parseFloat(reqRevision))
                    return true;
            }
        }
        return false;
    }
}

function AC_AddExtension(src, ext)
{
  if (src.indexOf('?') != -1)
    return src.replace(/\?/, ext+'?'); 
  else
    return src + ext;
}

function AC_Generateobj(objAttrs, params, embedAttrs) 
{ 
  var str = '';
  if (isIE && isWin && !isOpera)
  {
    str += '<object ';
    for (var i in objAttrs)
    {
      str += i + '="' + objAttrs[i] + '" ';
    }
    str += '>';
    for (var i in params)
    {
      str += '<param name="' + i + '" value="' + params[i] + '" /> ';
    }
    str += '</object>';
  }
  else
  {
    str += '<embed ';
    for (var i in embedAttrs)
    {
      str += i + '="' + embedAttrs[i] + '" ';
    }
    str += '> </embed>';
  }

  document.write(str);
}

function AC_FL_RunContent(){
  var ret = 
    AC_GetArgs
    (  arguments, ".swf", "movie", "clsid:d27cdb6e-ae6d-11cf-96b8-444553540000"
     , "application/x-shockwave-flash"
    );
  AC_Generateobj(ret.objAttrs, ret.params, ret.embedAttrs);
}

function AC_SW_RunContent(){
  var ret = 
    AC_GetArgs
    (  arguments, ".dcr", "src", "clsid:166B1BCA-3F9C-11CF-8075-444553540000"
     , null
    );
  AC_Generateobj(ret.objAttrs, ret.params, ret.embedAttrs);
}

function AC_GetArgs(args, ext, srcParamName, classid, mimeType){
  var ret = new Object();
  ret.embedAttrs = new Object();
  ret.params = new Object();
  ret.objAttrs = new Object();
  for (var i=0; i < args.length; i=i+2){
    var currArg = args[i].toLowerCase();    

    switch (currArg){    
      case "classid":
        break;
      case "pluginspage":
        ret.embedAttrs[args[i]] = args[i+1];
        break;
      case "src":
      case "movie":    
        args[i+1] = AC_AddExtension(args[i+1], ext);
        ret.embedAttrs["src"] = args[i+1];
        ret.params[srcParamName] = args[i+1];
        break;
      case "onafterupdate":
      case "onbeforeupdate":
      case "onblur":
      case "oncellchange":
      case "onclick":
      case "ondblclick":
      case "ondrag":
      case "ondragend":
      case "ondragenter":
      case "ondragleave":
      case "ondragover":
      case "ondrop":
      case "onfinish":
      case "onfocus":
      case "onhelp":
      case "onmousedown":
      case "onmouseup":
      case "onmouseover":
      case "onmousemove":
      case "onmouseout":
      case "onkeypress":
      case "onkeydown":
      case "onkeyup":
      case "onload":
      case "onlosecapture":
      case "onpropertychange":
      case "onreadystatechange":
      case "onrowsdelete":
      case "onrowenter":
      case "onrowexit":
      case "onrowsinserted":
      case "onstart":
      case "onscroll":
      case "onbeforeeditfocus":
      case "onactivate":
      case "onbeforedeactivate":
      case "ondeactivate":
      case "type":
      case "codebase":
      case "id":
        ret.objAttrs[args[i]] = args[i+1];
        break;
      case "width":
      case "height":
      case "align":
      case "vspace": 
      case "hspace":
      case "class":
      case "title":
      case "accesskey":
      case "name":
      case "tabindex":
        ret.embedAttrs[args[i]] = ret.objAttrs[args[i]] = args[i+1];
        break;
      default:
        ret.embedAttrs[args[i]] = ret.params[args[i]] = args[i+1];
    }
  }
  ret.objAttrs["classid"] = classid;
  if (mimeType) ret.embedAttrs["type"] = mimeType;
  return ret;
}

页面中这样调用即可

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh_cn" lang="zh_cn">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>flash</title>
<script language="javascript">AC_FL_RunContent = 0;</script>
<script src="AC_RunActiveContent.js" language="javascript"></script>
</head>
<body bgcolor="#333333">
<!--影片中使用的 URL-->
<!--影片中使用的文本-->
<!-- saved from url=(0013)about:internet -->
<script language="javascript">
    if (AC_FL_RunContent == 0) {
        alert("此页需要 AC_RunActiveContent.js");
    } else {
        AC_FL_RunContent(
            'codebase', 'http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,0,0',
            'width', '1000',
            'height', '700',
            'src', 'flash',
            'quality', 'high',
            'pluginspage', 'http://www.macromedia.com/go/getflashplayer',
            'align', 'middle',
            'play', 'true',
            'loop', 'true',
            'scale', 'showall',
            'wmode', 'window',
            'devicefont', 'false',
            'id', 'flash',
            'bgcolor', '#333333',
            'name', 'flash',
            'menu', 'true',
            'allowFullScreen', 'false',
            'allowScriptAccess','sameDomain',
            'movie', 'flash',
            'salign', ''
            ); //end AC code
    }
</script>
<noscript>
    <object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,0,0" width="1000" height="700" id="flash" align="middle">
    <param name="allowScriptAccess" value="sameDomain" />
    <param name="allowFullScreen" value="false" />
    <param name="movie" value="flash.swf" /><param name="quality" value="high" /><param name="bgcolor" value="#333333" />    <embed src="flash.swf" quality="high" bgcolor="#333333" width="1000" height="700" name="flash" align="middle" allowScriptAccess="sameDomain" allowFullScreen="false" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" />
    </object>
</noscript>
</body>
</html>