android手机时间自动同步
在Android2.3.4系统中，Settings->Date & time->Automatic项打上后，时间会通过网络进行同步，而Android默认使用的是NITZ来获取移动网络时间，需要有移动网络服务商的支持才能使用，而有些Android产品只支持WIFI等无线网络，而不支持移动网络，此时就需要采用SNTP方式来获取网络时间进行同步了，相应需要修改到的文件为
frameworks/base/telephony/java/com/android/internal/telephony /cdma/CdmaServiceStateTracker.java
frameworks/base/telephony/java/com /android/internal/telephony/gsm/GsmServiceStateTracker.java需要修改的都是一样的内容，如下：
添加如下内容：import android.net.SntpClient;修改如下内容：把private void revertToNitz() {if (Settings.System.getInt(phone.getContext().getContentResolver(),Settings.System.AUTO_TIME, 0) == 0) {return;}Log.d(LOG_TAG, "Reverting to NITZ: tz='" + mSavedTimeZone+ "' mSavedTime=" + mSavedTime+ " mSavedAtTime=" + mSavedAtTime);if (mSavedTimeZone != null && mSavedTime != 0 && mSavedAtTime != 0) {setAndBroadcastNetworkSetTimeZone(mSavedTimeZone);setAndBroadcastNetworkSetTime(mSavedTime+ (SystemClock.elapsedRealtime() - mSavedAtTime));}}修改为：
private void revertToNitz() {if (Settings.System.getInt(phone.getContext().getContentResolver(),Settings.System.AUTO_TIME, 0) == 0) {return;}Log.d(LOG_TAG, "Reverting to NITZ: tz='" + mSavedTimeZone+ "' mSavedTime=" + mSavedTime+ " mSavedAtTime=" + mSavedAtTime);if (mSavedTimeZone != null && mSavedTime != 0 && mSavedAtTime != 0) {setAndBroadcastNetworkSetTimeZone(mSavedTimeZone);setAndBroadcastNetworkSetTime(mSavedTime+ (SystemClock.elapsedRealtime() - mSavedAtTime));return;}int tryCount = 5;SntpClient client = new SntpClient();Log.i(LOG_TAG, "revertToNitz new sntpclient");for(int i = 0; i < tryCount; i++){if(client.requestTime("north-america.pool.ntp.org", 10000)) {long cachedNtp = client.getNtpTime();long cachedNtpTimestamp = SystemClock.elapsedRealtime();Log.i(LOG_TAG, "Sntp NtpTime = " + cachedNtp);setAndBroadcastNetworkSetTime(cachedNtp+ (SystemClock.elapsedRealtime() - client.getNtpTimeReference()));return;}}}当不支持NITZ获取时间同步时就使用SNTP方式获取时间进行同步。不过使用SNTP方式进行时间同步时不能同步时区，需要自己先去掉自动同步并设置时区后再设置自动同步，这样才能进行网络时间的同步更新。
时间同步 受地区 卡类别 基站 运营商 等影响大部分android手机时间同步都不怎么顺畅
android手机时间自动同步
在Android2.3.4系统中，Settings->Date & time->Automatic项打上后，时间会通过网络进行同步，而Android默认使用的是NITZ来获取移动网络时间，需要有移动网络服务商的支持才能使用，而有些Android产品只支持WIFI等无线网络，而不支持移动网络，此时就需要采用SNTP方式来获取网络时间进行同步了，相应需要修改到的文件为
frameworks/base/telephony/java/com/android/internal/telephony /cdma/CdmaServiceStateTracker.java
frameworks/base/telephony/java/com /android/internal/telephony/gsm/GsmServiceStateTracker.java需要修改的都是一样的内容，如下：
添加如下内容：import android.net.SntpClient;修改如下内容：把private void revertToNitz() {if (Settings.System.getInt(phone.getContext().getContentResolver(),Settings.System.AUTO_TIME, 0) == 0) {return;}Log.d(LOG_TAG, "Reverting to NITZ: tz='" + mSavedTimeZone+ "' mSavedTime=" + mSavedTime+ " mSavedAtTime=" + mSavedAtTime);if (mSavedTimeZone != null && mSavedTime != 0 && mSavedAtTime != 0) {setAndBroadcastNetworkSetTimeZone(mSavedTimeZone);setAndBroadcastNetworkSetTime(mSavedTime+ (SystemClock.elapsedRealtime() - mSavedAtTime));}}修改为：
private void revertToNitz() {if (Settings.System.getInt(phone.getContext().getContentResolver(),Settings.System.AUTO_TIME, 0) == 0) {return;}Log.d(LOG_TAG, "Reverting to NITZ: tz='" + mSavedTimeZone+ "' mSavedTime=" + mSavedTime+ " mSavedAtTime=" + mSavedAtTime);if (mSavedTimeZone != null && mSavedTime != 0 && mSavedAtTime != 0) {setAndBroadcastNetworkSetTimeZone(mSavedTimeZone);setAndBroadcastNetworkSetTime(mSavedTime+ (SystemClock.elapsedRealtime() - mSavedAtTime));return;}int tryCount = 5;SntpClient client = new SntpClient();Log.i(LOG_TAG, "revertToNitz new sntpclient");for(int i = 0; i < tryCount; i++){if(client.requestTime("north-america.pool.ntp.org", 10000)) {long cachedNtp = client.getNtpTime();long cachedNtpTimestamp = SystemClock.elapsedRealtime();Log.i(LOG_TAG, "Sntp NtpTime = " + cachedNtp);setAndBroadcastNetworkSetTime(cachedNtp+ (SystemClock.elapsedRealtime() - client.getNtpTimeReference()));return;}}}当不支持NITZ获取时间同步时就使用SNTP方式获取时间进行同步。不过使用SNTP方式进行时间同步时不能同步时区，需要自己先去掉自动同步并设置时区后再设置自动同步，这样才能进行网络时间的同步更新。
时间同步 受地区 卡类别 基站 运营商 等影响大部分android手机时间同步都不怎么顺畅