确定字符串中、出现特定字符串的次数

var s:String = "hellojavaeoojavapopejava";
//不这样做会改变原来的字符串s
var _s:String = s;
var s1:String = "java";
var index,count:int = 0;
while (_s.indexOf(s1)!=-1)
{
	index = _s.indexOf(s1);
	trace(index)
	_s = _s.substring(index + s1.length);
	count++;
}
trace("字符串出现次数---"+count);
trace(s);
trace(s1);