public static String stringFilterStrict(String searchText){
  return searchText.replaceAll("[^ a-zA-Z0-9\\u4e00-\\u9fa5]","");
}

public static String stringFilterStrict ( String searchText ) { return searchText . replaceAll ( "[^ a-zA-Z0-9\\u4e00-\\u9fa5]" , "" ) ; }
remove useless and unsafe characters . only chinese , numbers , english characters and space are allowed .
