我需要一个快速密钥替换算法的Java

import java.util.HashMap;
import java.util.Map;

public class KeyReplacementAlgorithm {
    private Map<Character, Character> keyMap;

    public KeyReplacementAlgorithm(Map<Character, Character> keyMap) {
        this.keyMap = keyMap;
    }

    public String replace(String input) {
        StringBuilder output = new StringBuilder();
        for (char c : input.toCharArray()) {
            if (keyMap.containsKey(c)) {
                output.append(keyMap.get(c));
            } else {
                output.append(c);
            }
        }
        return output.toString();
    }

    public static void main(String[] args) {
        Map<Character, Character> keyMap = new HashMap<>();
        keyMap.put('a', 'x');
        keyMap.put('b', 'y');
        keyMap.put('c', 'z');

        KeyReplacementAlgorithm algorithm = new KeyReplacementAlgorithm(keyMap);
        String input = "abc";
        String output = algorithm.replace(input);
        System.out.println("Input: " + input);
        System.out.println("Output: " + output);
    }
}