汉字转化为unicode

public static String gbkToUnicode(String s) throws Exception {
if(s == null) return null;
char []chars = s.toCharArray();
StringBuffer result = new StringBuffer();
String temp = "";
for(int i = 0;i < chars.length; i++) {
temp = Integer.toHexString((int)chars[i]).toUpperCase();
result.append("//"+"u");
if(temp.length()!=4) {
for(int j=0;j<4-temp.length();j++) {
result.append("0");
}
}
result.append(temp);
}
return result.toString();
}