md5Hex(token&t&appKey&data)

public static String calcSignature(String token, String timestamp, String appKey, String data) {
        return DigestUtils.md5Hex(StringUtils.trimToEmpty(token) + "&"
                + timestamp + "&" + appKey + "&" + data);
    }

    public static void main(String[] args) {
        String token="30dc68e5b4cf40ebd02fb05673c7e3b7";
        String timestamp="1572522062317";
        String sign = calcSignature(token, timestamp, "12345678", "{\"itemNumId\":\"1502111132496\"}");
        System.out.println(sign);
    }

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class Credentials implements Comparable<Credentials> {
    private String _m_h5_tk;
    private String _m_h5_tk_enc;

    private static final int OFFSET = 60000;

    public String getToken() {
        return StringUtils.isEmpty(_m_h5_tk) ? null : _m_h5_tk.substring(0, _m_h5_tk.indexOf("_"));
    }

    public long getExpireTimestamp() {
        long t = new Date().getTime() - OFFSET;
        if (StringUtils.isEmpty(_m_h5_tk) || StringUtils.isEmpty(_m_h5_tk_enc)) {
            return t;
        }
        try {
            return Long.parseLong(_m_h5_tk.substring(_m_h5_tk.indexOf("_") + 1));
        } catch (NumberFormatException e) {
            return t;
        }
    }

    public boolean isExpired() {
        if (StringUtils.isEmpty(_m_h5_tk) || StringUtils.isEmpty(_m_h5_tk_enc)) {
            return true;
        }
        return new Date().getTime() > getExpireTimestamp();
    }

    @Override
    public int compareTo(Credentials o) {
        return Long.compare(o.getExpireTimestamp(), this.getExpireTimestamp());
    }
}