public static String htmlFilter(String input) {
StringBuffer filtered = new StringBuffer(input.length());
char c;
for (int i = 0; i < input.length(); i++) {
c = input.charAt(i);
if ( c == '<') {
filtered.append("&");
} else if (c == '>') {
filtered.append("&");
} else if (c == '"') {
filtered.append("&");
} else if (c == '&') {
filtered.append("&");
} else {
filtered.append(c);
}
}
return filtered.toString();
}