MTK NTP和NITZ更新时间的问题
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MTK NTP和NITZ更新时间的问题
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NITZ(Network Identity and Time Zone，網(wǎng)絡標識和時區(qū)），是一種用于自動配置本地的時間和日期的機制，同時也通過無線網(wǎng)向移動設備提供運營商信息。NITZ是自從PHASE 2+ RELEASE 96 的GSM中的可選功能，經(jīng)常被用來自動更新移動電話的系統(tǒng)時鐘。NITZ需要運營商網(wǎng)絡支持（通過CS網(wǎng)絡），目前國內電信、移動都支持NITZ方式更新時間日期，而聯(lián)通目前不支持。
一。配置服務器端：
那么比如在英國的話就可以選擇下面兩個服務器
0.uk.pool.ntp.org 1.uk.pool.ntp.org
它的一般格式都是number.country.pool.ntp.org
中國的ntp服務器地址:
server 133.100.11.8 prefer server 210.72.145.44 server 203.117.180.36 server 131.107.1.10 server time.asia.apple.com server 64.236.96.53 server 130.149.17.21 server 66.92.68.246 server www.freebsd.org server 18.145.0.30 server clock.via.net server 137.92.140.80 server 133.100.9.2 server 128.118.46.3 server ntp.nasa.gov server 129.7.1.66 server ntp-sop.inria.fr server (國家授時中心服務器IP地址)
二。修改默認NTP配置
1.通過SntpClient.java來封裝請求。
frameworks/base/core/java/android/net/SntpClient.java
public boolean requestTime(String host, int timeout) {
DatagramSocket socket = null;
try {
socket = new DatagramSocket();
socket.setSoTimeout(timeout);
InetAddress address = InetAddress.getByName(host);
byte[] buffer = new byte[NTP_PACKET_SIZE];
DatagramPacket request = new DatagramPacket(buffer, buffer.length, address, NTP_PORT);
// set mode = 3 (client) and version = 3
// mode is in low 3 bits of first byte
// version is in bits 3-5 of first byte
buffer[0] = NTP_MODE_CLIENT | (NTP_VERSION << 3);
// get current time and write it to the request packet
long requestTime = System.currentTimeMillis();
long requestTicks = SystemClock.elapsedRealtime();
writeTimeStamp(buffer, TRANSMIT_TIME_OFFSET, requestTime);
socket.send(request);
// read the response
DatagramPacket response = new DatagramPacket(buffer, buffer.length);
socket.receive(response);
long responseTicks = SystemClock.elapsedRealtime();
long responseTime = requestTime + (responseTicks - requestTicks);
// extract the results
long originateTime = readTimeStamp(buffer, ORIGINATE_TIME_OFFSET);
long receiveTime = readTimeStamp(buffer, RECEIVE_TIME_OFFSET);
long transmitTime = readTimeStamp(buffer, TRANSMIT_TIME_OFFSET);
long roundTripTime = responseTicks - requestTicks - (transmitTime - receiveTime);
// receiveTime = originateTime + transit + skew
// responseTime = transmitTime + transit - skew
// clockOffset = ((receiveTime - originateTime) + (transmitTime - responseTime))/2
// = ((originateTime + transit + skew - originateTime) +
// (transmitTime - (transmitTime + transit - skew)))/2
// = ((transit + skew) + (transmitTime - transmitTime - transit + skew))/2
// = (transit + skew - transit + skew)/2
// = (2 * skew)/2 = skew
long clockOffset = ((receiveTime - originateTime) + (transmitTime - responseTime))/2;
// if (false) Log.d(TAG, round trip: + roundTripTime + ms);
// if (false) Log.d(TAG, clock offset: + clockOffset + ms);
// save our results - use the times on this side of the network latency
// (response rather than request time)
mNtpTime = responseTime + clockOffset;
mNtpTimeReference = responseTicks;
mRoundTripTime = roundTripTime;
} catch (Exception e) {
if (false) Log.d(TAG, request time failed: + e);
return false;
} finally {
if (socket != null) {
socket.close();
}
}
return true;
}
2.發(fā)起同步的，這個方法的主角為：NtpTrustedTime.java 在該類中通過forceRefresh方法來更新獲取服務器時間。
frameworks/base/core/java/android/util/NtpTrustedTime.java
public boolean forceRefresh() {
if (mServer == null) {
// missing server, so no trusted time available
return false;
}
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;
}
}
3.時間同步請求處理邏輯。在onPollNetworkTime方法中進行同步處理。
/frameworks/base/services/core/java/com/android/server/NetworkTimeUpdateService.java
private void onPollNetworkTime(int event) {
//1、是否勾選自動同步時間配置
// If Automatic time is not set, don't bother.
if (!isAutomaticTimeRequested()) return;
//2、mNitzTimeSetTime 來自Moderm，如果當前時間剛通過moderm更新不久，則不進行時間同步。
final long refTime = SystemClock.elapsedRealtime();
// If NITZ time was received less than mPollingIntervalMs time ago,
// no need to sync to NTP.
if (mNitzTimeSetTime != NOT_SET && refTime - mNitzTimeSetTime < mPollingIntervalMs) {
resetAlarm(mPollingIntervalMs);
return;
}
//3、如果機器剛啟動，或者機器運行時間大于mPollingIntervalMs，即10天，或者設置等發(fā)起的主動更新時間請求，則發(fā)起網(wǎng)絡時間同步請求。否則，10天后再進行時間同步。
final long currentTime = System.currentTimeMillis();
if (DBG) Log.d(TAG, System time = + currentTime);
// Get the NTP time
if (mLastNtpFetchTime == NOT_SET || refTime >= mLastNtpFetchTime + mPollingIntervalMs
|| event == EVENT_AUTO_TIME_CHANGED) {
if (DBG) Log.d(TAG, Before Ntp fetch);
//3.1、是否含有時間緩沖，如無，發(fā)起時間同步，
// force refresh NTP cache when outdated
if (mTime.getCacheAge() >= mPollingIntervalMs) {
//LEUI-START [BUG][MOBILEP-6067] [System time sync added
//mTime.forceRefresh();
int index = mTryAgainCounter % mNtpServers.size();
if (DBG) Log.d(TAG, mTryAgainCounter = + mTryAgainCounter + ;mNtpServers.size() = + mNtpServers.size() + ;index = + index + ;mNtpServers = + mNtpServers.get(index));
//3.1.1、遍歷時間服務器，發(fā)起時間同步
if (mTime instanceof NtpTrustedTime)
{
((NtpTrustedTime) mTime).setServer(mNtpServers.get(index));
mTime.forceRefresh();
((NtpTrustedTime) mTime).setServer(mDefaultServer);
}
else
{
mTime.forceRefresh();
}
//LEUI-END [BUG][MOBILEP-6067] [System time sync added
}
//3.2、獲取最新同步的時間緩沖數(shù)據(jù)，如無，則再次發(fā)起時間同步，間隔時間為mPollingIntervalShorterMs，即30秒。
// only update when NTP time is fresh
if (mTime.getCacheAge() < mPollingIntervalMs) {
final long ntp = mTime.currentTimeMillis();
mTryAgainCounter = 0;
// If the clock is more than N seconds off or this is the first time it's been
// fetched since boot, set the current time.
//3.2.1、如果開機第一次同步或者最新時間與當前時間差別超過mTimeErrorThresholdMs即25秒，則進行時間設定。否則認定新同步時間與當前時間差別不大，不覆蓋當前時間。
if (Math.abs(ntp - currentTime) > mTimeErrorThresholdMs
|| mLastNtpFetchTime == NOT_SET) {
// Set the system time
if (DBG && mLastNtpFetchTime == NOT_SET
&& Math.abs(ntp - currentTime) <= mTimeErrorThresholdMs) {
Log.d(TAG, For initial setup, rtc = + currentTime);
}
if (DBG) Log.d(TAG, Ntp time to be set = + ntp);
// Make sure we don't overflow, since it's going to be converted to an int
//3.2.2、設定同步時間
if (ntp / 1000 < Integer.MAX_VALUE) {
SystemClock.setCurrentTimeMillis(ntp);
}
} else {
if (DBG) Log.d(TAG, Ntp time is close enough = + ntp);
}
mLastNtpFetchTime = SystemClock.elapsedRealtime();
} else {
// Try again shortly
//3.3 如果不大于最大同步次數(shù)，30秒后進行時間同步，否則，10天后更新。
mTryAgainCounter++;
if (mTryAgainTimesMax < 0 || mTryAgainCounter <= mTryAgainTimesMax) {
resetAlarm(mPollingIntervalShorterMs);
} else {
// Try much later
mTryAgainCounter = 0;
resetAlarm(mPollingIntervalMs);
}
return;
}
}
//4、如果剛更新時間不久，則10天后再發(fā)起時間同步請求。
resetAlarm(mPollingIntervalMs);
}
4.減小NTP請求的時間，確保開機聯(lián)網(wǎng)立即同步時間
/frameworks/base/core/res/res/values/config.xml
<integer name="config_ntpPollingIntervalShorter">10000</integer>
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