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1. NTP介绍
NTP#xff1a;网络时间协议#xff0c;英文名称#xff1a;Network Time Protocol#xff08;NTP#xff09;是用来使计算机时间同步化的一种协议#xff0c;它可以使计算机对其服务器或时钟源#xff08;如石英钟#x…一现象
1. NTP介绍
NTP网络时间协议英文名称Network Time ProtocolNTP是用来使计算机时间同步化的一种协议它可以使计算机对其服务器或时钟源如石英钟GPS等等)做同步化它可以提供高精准度的时间校正LAN上与标准间差小于1毫秒WAN上几十毫秒且可介由加密确认的方式来防止恶毒的协议攻击。NTP的目的是在无序的Internet环境中提供精确和健壮的时间服务。
Android系统使用NTP自动更新系统时间的触发机制 监听数据库字段AUTO_TIME当这个字段发生变化的时候会立即触发一次时间同步 网络连接发生变化当网络接通会触发一次时间检查和同步 定时更新机制当预定的时间到了会触发一次时间检查和同步 Android自动同步时间是通过NtpServer来同步时间的但是默认的服务器使用的是Google的所以无法连接会导致自动同步日期和时间无效。
2. NTP时间设置流程示意图 二解决方案
以下修改都在源码frameworks/base/下
1. 修改默认的Ntp服务器
diff --git a/packages/SettingsProvider/res/values/defaults.xml b/packages/SettingsProvider/res/values/defaults.xml
index 129cee58078..8ffc237c7e1 100755
--- a/packages/SettingsProvider/res/values/defaults.xmlb/packages/SettingsProvider/res/values/defaults.xml-229,4 229,6 integer namedef_screenshot_button_show1/integer!-- the store location of screen capture by default--string namedef_screenshot_locationinternal_storage/stringstring namedef_ntp_server translatablefalsetime.windows.com/string
/resourcesdiff --git a/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java b/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java
index 0ba3a5289ed..29361ad19bc 100644
--- a/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.javab/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java-2733,6 2733,9 class DatabaseHelper extends SQLiteOpenHelper {loadSetting(stmt, Settings.Global.ENHANCED_4G_MODE_ENABLED,ImsConfig.FeatureValueConstants.ON); loadStringSetting(stmt, Settings.Global.NTP_SERVER,R.string.def_ntp_server);
/** IMPORTANT: Do not add any more upgrade steps here as the global,* secure, and system settings are no longer stored in a database2. 修改NTP基础配置
!-- Remote server that can provide NTP responses. --
string translatablefalse nameconfig_ntpServer2.android.pool.ntp.org/string
!-- Normal polling frequency in milliseconds --
integer nameconfig_ntpPollingInterval86400000/integer
!-- Try-again polling interval in milliseconds, in case the network request failed --
integer nameconfig_ntpPollingIntervalShorter30000/integer
!-- Number of times to try again with the shorter interval, before backingoff until the normal polling interval. A value 0 indicates infinite. --
integer nameconfig_ntpRetry5/integer
!-- Timeout to wait for NTP server response in milliseconds. --
integer nameconfig_ntpTimeout10/integer 2.android.pool.ntp.org这个是NTP服务器地址 86400000周期默认8640000ms即1天一般不改 30000是由于网络原因时间同步失败后retry的时间间隔默认是60000ms即60s这里改成30s 5retry的次数默认是3次 10时间误差默认是5000ms当时间误差超过5s会更新系统时间改成10ms. wifi自动确定时间的问题时NTP服务器可以自行更换为自己增加列表中的地址例如
string translatablefalse nameconfig_ntpServerntp1.aliyun.com/string3. 增加NTP列表
添加多个Ntp服务器用于轮询避免默认Ntp服务器失效安卓10以后ntp的判定规则有所不同所以代码有所差异。
1. Android10之前Android7.1修改
diff --git a/core/java/android/util/NtpTrustedTime.java b/core/java/android/util/NtpTrustedTime.java
index ed2d3c60fcd..60ad5d9f132 100644
--- a/core/java/android/util/NtpTrustedTime.javab/core/java/android/util/NtpTrustedTime.java-39,7 39,7 public class NtpTrustedTime implements TrustedTime {private static NtpTrustedTime sSingleton;private static Context sContext;- private final String mServer;private String mServer;private final long mTimeout;private ConnectivityManager mCM;-49,6 49,15 public class NtpTrustedTime implements TrustedTime {private long mCachedNtpElapsedRealtime;private long mCachedNtpCertainty; String[] backupNtpServers new String[]{tw.pool.ntp.org,time.nist.gov,time-a.nist.gov,ntp1.aliyun.com};int index -1;private NtpTrustedTime(String server, long timeout) {if (LOGD) Log.d(TAG, creating NtpTrustedTime using server);mServer server;-101,15 110,29 public class NtpTrustedTime implements TrustedTime {if (LOGD) Log.d(TAG, forceRefresh() from cache miss);final SntpClient client new SntpClient();
- if (client.requestTime(mServer, (int) mTimeout)) {
- mHasCache true;
- mCachedNtpTime client.getNtpTime();
- mCachedNtpElapsedRealtime client.getNtpTimeReference();
- mCachedNtpCertainty client.getRoundTripTime() / 2;
- return true;
- } else {
- return false;boolean result false;while(!(result client.requestTime(mServer, (int)mTimeout)) index (backupNtpServers.length-1)){index;mServer backupNtpServers[index];}index -1;Resources res sContext.getResources();String defaultServer res.getString(com.android.internal.R.string.config_ntpServer);String secureServer Settings.Global.getString(sContext.getContentResolver(), Settings.Global.NTP_SERVER);mServer secureServer ! null ? secureServer : defaultServer;if(result){mHasCache true;mCachedNtpTime client.getNtpTime();mCachedNtpElapsedRealtime client.getNtpTimeReference();mCachedNtpCertainty client.getRoundTripTime() / 2;}return result;}Override2. Android10之后Android11.0修改
diff --git a/frameworks/base/core/java/android/util/NtpTrustedTime.java b/frameworks/base/core/java/android/util/NtpTrustedTime.java
old mode 100644
new mode 100755
index 0892c94d5b..bb8f894cb3
--- a/frameworks/base/core/java/android/util/NtpTrustedTime.javab/frameworks/base/core/java/android/util/NtpTrustedTime.java-98,6 98,27 public class NtpTrustedTime implements TrustedTime {private static NtpTrustedTime sSingleton;String[] backupNtpServers new String[]{time.nist.gov,time-a.nist.gov,ntp1.aliyun.com,ntp2.aliyun.com,ntp3.aliyun.com,ntp-sz.chl.la,3.cn.pool.ntp.org,asia.pool.ntp.org,cn.pool.ntp.org,sg.pool.ntp.org,jp.pool.ntp.org,hk.pool.ntp.org,s2g.time.edu.cn,oceania.pool.ntp.org,south-america.pool.ntp.org,north-america.pool.ntp.org,tw.pool.ntp.org,};int index -1;
NonNullprivate final Context mContext;-162,12 183,18 public class NtpTrustedTime implements TrustedTime {if (LOGD) Log.d(TAG, forceRefresh() from cache miss);final SntpClient client new SntpClient();
- final String serverName connectionInfo.getServer();boolean result false;String serverName connectionInfo.getServer();if (LOGD) Log.d(TAG, ----------rockemd-add-20221027-serverName--1------serverName);final int timeoutMillis connectionInfo.getTimeoutMillis();
- if (client.requestTime(serverName, timeoutMillis, network)) {while (!(result client.requestTime(serverName, timeoutMillis, network)) index (backupNtpServers.length-1) ) {index;serverName backupNtpServers[index];if (LOGD) Log.d(TAG, ----------rockemd-add-20221027-serverName--------serverName);}if(result){long ntpCertainty client.getRoundTripTime() / 2;
- mTimeResult new TimeResult(
- client.getNtpTime(), client.getNtpTimeReference(), ntpCertainty);mTimeResult new TimeResult(client.getNtpTime(), client.getNtpTimeReference(), ntpCertainty);return true;} else {return false;三调试
1. 通过adb更改当前服务器地址
adb shell settings put global ntp_server ntp.ntsc.ac.cn //更改服务器地址
adb shell setprop persist.sys.timezone Asia/Shangha //更改时区
adb shell settings get global ntp_server //查看当前使用地址
adb shel1 settings put global auto_time 1 //打开网络同步时间开关
adb shel1 settings put global auto_time 0 //关闭网络同步时间开关
