Java 字串 Unicode \u 顯示

public static String escapeUnicode(String input) {
StringBuilder b = new StringBuilder(input.length());
Formatter f = new Formatter(b);
for (char c : input.toCharArray()) {
if (c < 128) {
b.append(c);
} else {
f.format("\\u%04x", (int) c);
}
}
return b.toString();
}