应用调用 API 接口

import org.apache.commons.lang3.RandomStringUtils;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Objects;

public class SignUtil {

    /**
     * 生成签名
     *
     * @param appId      应用ID
     * @param appSecret  应用密钥
     * @return 生成的签名
     */
    public static String generateSign(Long appId, String appSecret) throws NoSuchAlgorithmException {
        Objects.requireNonNull(appId, "应用ID不能为空");
        Objects.requireNonNull(appSecret, "应用密钥不能为空");

        long timestamp = System.currentTimeMillis();
        String nonce = RandomStringUtils.randomAlphanumeric(32);
        String strToMD5 = "appId=" + appId + "&appSecret=" + appSecret + "&nonce=" + nonce + "&timestamp=" + timestamp;
        return calculateMD5(strToMD5);
    }

    /**
     * 计算字符串的MD5哈希值
     *
     * @param plainText 待计算的字符串
     * @return 字符串的MD5哈希值
     */
    public static String calculateMD5(String plainText) throws NoSuchAlgorithmException {
        Objects.requireNonNull(plainText, "输入字符串不能为空");

        MessageDigest md = MessageDigest.getInstance("MD5");
        byte[] hashBytes = md.digest(plainText.getBytes(StandardCharsets.UTF_8));

        StringBuilder md5code = new StringBuilder();
        for (byte b : hashBytes) {
            String hex = Integer.toHexString(0xFF & b);
            if (hex.length() == 1) {
                md5code.append("0");
            }
            md5code.append(hex);
        }

        return md5code.toString();
    }
}