DouKaku?

import java.util.regex._
class ExtendedString(self:String) {
  def gsub(reg:Pattern, f:(Matcher)=>String):String = {
    val result = new StringBuffer
    val m = reg.matcher(self)
    while(m.find) m.appendReplacement(result, f(m))
    m.appendTail(result)
    result.toString
  }
  def gsub(reg:String, f:(Matcher)=>String):String = gsub(Pattern.compile(reg), f)
}
implicit def string2ext(self:String) = new ExtendedString(self);


object htmlEscape{
  lazy val tagRegex = Pattern.compile(
    """(</?)([^"'< >]*)([^"'<>]*(?:"[^"]*"[^"'<>]*|'[^']*'[^"'<>]*)*)((?:>|(?=<)|$(?!\n)))"""
  )
  lazy val attrRegex = Pattern.compile(
    """[\s'"](\w+)\s*=\s*([^\s'">]+|'[^']+'|\"[^"]+")"""
  , Pattern.DOTALL | Pattern.CASE_INSENSITIVE)
  lazy val tagAllowed = Set("a", "br", "strong")
  lazy val attrAllowed = Map("a" -> Set("href", "name"))

  def apply(html:String) = {
    html.gsub(tagRegex, (m:Matcher) => {
      val tag = m.group(2).toLowerCase.replace("/","")
      (if(tagAllowed.contains(tag)){
        val attrs = m.group(3).gsub(attrRegex, (m2:Matcher) => {
          if(attrAllowed.getOrElse(tag, Set[String]()).contains(m2.group(1).toLowerCase)) {
            m2.group(0)
          }else {
            ""
          }
        })
        List(m.group(1),m.group(2), attrs, m.group(4))
      }else {
        List(m.group(1).replace("<", "&lt;"), m.group(2), m.group(3), m.group(4))
      }).mkString("")
    })
  }
}
println(htmlEscape("""<a href='www.google.com'>link</a> <blink>and</blink> <strong onClick='alert("NG")'>click<br/>me!</strong>"""))