Android 修改ntp网络校时服务器

SystemService启动后创建NetworkTimeUpdateService网络校时服务，构造方法加载配置文件，默认配置文件位置在/frameworks/base/core/res/res/values/config.xml，定制部分放在/vendor方案商的定制目录。

XML 复制代码

    <!-- Remote server that can provide NTP responses. -->
    <string translatable="false" name="config_ntpServer">time.android.com</string>
    <!-- Normal polling frequency in milliseconds -->
    <integer name="config_ntpPollingInterval">64800000</integer>
    <!-- Try-again polling interval in milliseconds, in case the network request failed -->
    <integer name="config_ntpPollingIntervalShorter">60000</integer>
    <!-- Number of times to try again with the shorter interval, before backing
         off until the normal polling interval. A value < 0 indicates infinite. -->
    <integer name="config_ntpRetry">3</integer>
    <!-- Timeout to wait for NTP server response in milliseconds. -->
    <integer name="config_ntpTimeout">5000</integer>

config_ntpServer：默认NTP服务器，方案商定制可能换成2.android.pool.ntp.org

config_ntpPollingInterval：开机后的轮询间隔时间

NetworkTimeUpdateService在网络连接后，轮训校时。

打开frameworks/base/core/java/android/util/NtpTrustedTime.java，找到getNtpConnectionInfo方法：

java 复制代码

    private NtpConnectionInfo getNtpConnectionInfo() {
        .......................................
        final String hostname;
        if (mHostnameForTests != null) {
            hostname = mHostnameForTests;
        } else {
            String serverGlobalSetting =
                    Settings.Global.getString(resolver, Settings.Global.NTP_SERVER);
            if (serverGlobalSetting != null) {
                hostname = serverGlobalSetting;
            } else {
                hostname = res.getString(com.android.internal.R.string.config_ntpServer);
            }
        }
        ........................................
        return TextUtils.isEmpty(hostname) ? null :
            new NtpConnectionInfo(hostname, port, timeoutMillis);
    }

Settings.Global中NTP_SERVER的值：

public static final String NTP_SERVER = "ntp_server";

按照方法逻辑，当Settings.Global.NTP_SERVER的值为空时，系统取默认的ntp服务器。

修改ntp网络校时服务器就有两种选择：

1、不修改系统：

adb shell settings put global ntp_server xxx.xxx.xxx.xxx

xxx.xxx.xxx.xxx为服务器IP

adb shell settings get global ntp_server，查看修改后的值

2、修改系统

修改config_ntpServer的值