import java.awt.*;
import java.io.*;
public class UnicodeToCharEntities extends java.applet.Applet {

    int getUnicodeNumber(char ch) {
        return (int)ch;
    }

    boolean isEncodable(char ch, String enc) {
        String originalString = new Character(ch).toString();
        byte[] encodedByteArray = null;
        String decodedString = null;
        try{
            encodedByteArray = originalString.getBytes(enc);
	}catch(UnsupportedEncodingException e){
	    return false;
        }catch(Exception e){
        }
        try{
            decodedString = new String(encodedByteArray, enc);
        }catch(Exception e){
        }
        return decodedString.equals(originalString);
    }
    
    public String convertToCharEntitiesUnlessEncodable(String orig, String enc) {
        StringBuffer outputString = new StringBuffer("");
        for(int i = 0; i < orig.length(); ++i){
            if(this.isEncodable(orig.charAt(i), enc)) {
                outputString.append(orig.charAt(i));
            } else {
                outputString.append("&#" + this.getUnicodeNumber(orig.charAt(i)) +";");
            }
        }
        return outputString.toString();
    }
}