Java，然后这个案例弄好久没明白，求解答

怎么实现这个案例，解题思路看迷糊了，然后这个案例好久没弄明白，求解答解答，不胜感激

public static String stringToBinary(String s) {
    StringBuilder binary = new StringBuilder();
    for (char c : s.toCharArray()) {
        String asciiBinary = Integer.toBinaryString(c);
        while (asciiBinary.length() < 8) {
            asciiBinary = "0" + asciiBinary;
        }
        binary.append(asciiBinary);
    }
    return binary.toString();
}