java中的md5加密 字典排序

MD5是一种广泛使用的哈希函数，在Java中，你可以使用`java.security.MessageDigest`类及其`getInstance()`方法来生成MD5散列值。例如：

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;

public class MD5Example {
    public static String computeMD5(String input) {
        try {
            Mac mac = Mac.getInstance("HmacSHA256");
            byte[] keyBytes = "your-secret-key".getBytes(StandardCharsets.UTF_8);
            SecretKeySpec secretKey = new SecretKeySpec(keyBytes, "HmacSHA256");
            mac.init(secretKey);
            byte[] hashBytes = mac.doFinal(input.getBytes(StandardCharsets.UTF_8));
            return bytesToHex(hashBytes);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    private static String bytesToHex(byte[] bytes) {
        StringBuilder result = new StringBuilder();
        for (byte b : bytes) {
            result.append(String.format("%02x", b & 0xff));
        }
        return result.toString();
    }

    // 示例
    public static void main(String[] args) {
        String input = "Hello World";
        String md5 = computeMD5(input);
        System.out.println("MD5 Hash: " + md5);
    }
}

字典排序（也称为自然排序或基数排序）通常用于整数数组的排序，Java本身并不内置对字符串进行字典排序的功能。但在实际编程中，你可以通过比较字符的Unicode编码来实现基本的字典顺序。例如：

public int compareStrings(String s1, String s2) {
    for (int i = 0; i < Math.min(s1.length(), s2.length()); i++) {
        if (s1.charAt(i) != s2.charAt(i)) {
            return Integer.compare(s1.charAt(i), s2.charAt(i));
        }
    }
    return s1.length() - s2.length();
}

// 示例
String[] words = {"banana", "apple", "cherry"};
Arrays.sort(words, compareStrings);
System.out.println(Arrays.toString(words)); // 输出: [apple, banana, cherry]