Function to Remove Extended Characters

I wrote a ColdFusion function today that I thought I would share. What it does is replace extended, or unicode characters with HTML/XML character entities. EG: the character à becomes à.

I wrote this for an RSS feed that had a few unicode characters in it, but the majority of the feed was us-ascii. Rather than changing the encoding, I opted to replace those few chars with an ascii safe XML representation.

Here's The function:

<cffunction name="EscapeExtendedChars" returntype="string">
	<cfargument name="str" type="string" required="true">
	<cfset var buf = CreateObject("java", "java.lang.StringBuffer")>
	<cfset var len = Len(arguments.str)>
	<cfset var char = "">
	<cfset var charcode = 0>
	<cfset buf.ensureCapacity(JavaCast("int", len+20))>
	<cfif NOT len>
		<cfreturn arguments.str>
	</cfif>
	<cfloop from="1" to="#len#" index="i">
		<cfset char = arguments.str.charAt(JavaCast("int", i-1))>
		<cfset charcode = JavaCast("int", char)>
		<cfif (charcode GT 31 AND charcode LT 127) OR charcode EQ 10
			OR charcode EQ 13 OR charcode EQ 9>
				<cfset buf.append(JavaCast("string", char))>
		<cfelse>
			<cfset buf.append(JavaCast("string", "&##"))>
			<cfset buf.append(JavaCast("string", charcode))>
			<cfset buf.append(JavaCast("string", ";"))>
		</cfif>
	</cfloop>
	<cfreturn buf.toString()>
</cffunction>

I'm making use of Java's StringBuffer class, and also the charAt method of java.lang.String. I think this code is a pretty fast solution, since it avoid appending strings by hand, and I would guess the charAt method may be a bit faster than using the builtin CFML Mid function.