NTPTimeUtils
public class NtpTimeUtils {
// NTP服务器地址，同步获取网络时间（网络获取的时间已处理夏令时）
private static String[] ntpServerHost = new String[]{
"cn.pool.ntp.org",
"ntp1.aliyun.com",
"ntp2.aliyun.com",
"ntp3.aliyun.com"
};
// AndroidManifest.xml需要添加权限
private static String[] networkPermissions = new String[]{
Manifest.permission.INTERNET,
Manifest.permission.ACCESS_NETWORK_STATE
};
// 运行在子线程
@WorkerThread
private static long getTimeFromNtpServer(String ntpHost) {
SntpClient client = new SntpClient();
boolean isSuccessful = client.requestTime(ntpHost, 3000);
if (isSuccessful) {
return client.getNtpTime();
}
return -1;
}
// 运行在子线程
@WorkerThread
public static long getTime() {
for (String host : ntpServerHost) {
// 获取到当前时区时间的时间戳
// int diff = time - System.currentTimeMillis(); 缓存时间差
// long currTime = System.currentTimeMillis() + diff; 获取当前时间
long time = getTimeFromNtpServer(host);
if (time != -1) {
return time;
}
}
return -1;
}
/**
* 系统Setting是否打开网络获取时间开关
*/
public static boolean isAutoTime(Context context) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
try {
return Settings.Global.getInt(context.getContentResolver(), Settings.Global.AUTO_TIME) > 0;
} catch (Settings.SettingNotFoundException e) {
e.printStackTrace();
return false;
}
}
return false;
}
/**
* 是否连接网络
*/
public static boolean isNetworkActive(Context context) {
for (String permission : networkPermissions) {
if (ContextCompat.checkSelfPermission(context, permission) == PackageManager.PERMISSION_DENIED) {
return false;
}
}
ConnectivityManager cmm = (ConnectivityManager) context.getSystemService(CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = cmm.getActiveNetworkInfo();
return networkInfo != null && networkInfo.isConnected();
}
/**
* 系统Setting是否打开时间显示为24小时开关
*/
public static boolean is24HourFormat(Context context) {
return DateFormat.is24HourFormat(context);
}
}
public class SntpClient {
private static final String TAG = "SntpClient";
private static final int REFERENCE_TIME_OFFSET = 16;
private static final int ORIGINATE_TIME_OFFSET = 24;
private static final int RECEIVE_TIME_OFFSET = 32;
private static final int TRANSMIT_TIME_OFFSET = 40;
private static final int NTP_PACKET_SIZE = 48;
private static final int NTP_PORT = 123;
private static final int NTP_MODE_CLIENT = 3;
private static final int NTP_VERSION = 3;
// Number of seconds between Jan 1, 1900 and Jan 1, 1970
// 70 years plus 17 leap days
private static final long OFFSET_1900_TO_1970 = ((365L * 70L) + 17L) * 24L * 60L * 60L;
// system time computed from NTP server response
private long mNtpTime;
// value of SystemClock.elapsedRealtime() corresponding to mNtpTime
private long mNtpTimeReference;
// round trip time in milliseconds
private long mRoundTripTime;
/**
* Sends an SNTP request to the given host and processes the response.
*
* @param host host name of the server.
* @param timeout network timeout in milliseconds.
* @return true if the transaction was successful.
*/
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);
long clockOffset = ((receiveTime - originateTime) + (transmitTime - responseTime))/2;
// 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) {
Log.d(TAG, "request time failed: " + e);
return false;
} finally {
if (socket != null) {
socket.close();
}
}
return true;
}
/**
* Returns the time computed from the NTP transaction.
*
* @return time value computed from NTP server response.
*/
public long getNtpTime() {
return mNtpTime;
}
/**
* Returns the reference clock value (value of SystemClock.elapsedRealtime())
* corresponding to the NTP time.
*
* @return reference clock corresponding to the NTP time.
*/
public long getNtpTimeReference() {
return mNtpTimeReference;
}
/**
* Returns the round trip time of the NTP transaction
*
* @return round trip time in milliseconds.
*/
public long getRoundTripTime() {
return mRoundTripTime;
}
/**
* Reads an unsigned 32 bit big endian number from the given offset in the buffer.
*/
private long read32(byte[] buffer, int offset) {
byte b0 = buffer[offset];
byte b1 = buffer[offset+1];
byte b2 = buffer[offset+2];
byte b3 = buffer[offset+3];
// convert signed bytes to unsigned values
int i0 = ((b0 & 0x80) == 0x80 ? (b0 & 0x7F) + 0x80 : b0);
int i1 = ((b1 & 0x80) == 0x80 ? (b1 & 0x7F) + 0x80 : b1);
int i2 = ((b2 & 0x80) == 0x80 ? (b2 & 0x7F) + 0x80 : b2);
int i3 = ((b3 & 0x80) == 0x80 ? (b3 & 0x7F) + 0x80 : b3);
return ((long)i0 << 24) + ((long)i1 << 16) + ((long)i2 << 8) + (long)i3;
}
/**
* Reads the NTP time stamp at the given offset in the buffer and returns
* it as a system time (milliseconds since January 1, 1970).
*/
private long readTimeStamp(byte[] buffer, int offset) {
long seconds = read32(buffer, offset);
long fraction = read32(buffer, offset + 4);
return ((seconds - OFFSET_1900_TO_1970) * 1000) + ((fraction * 1000L) / 0x100000000L);
}
/**
* Writes system time (milliseconds since January 1, 1970) as an NTP time stamp
* at the given offset in the buffer.
*/
private void writeTimeStamp(byte[] buffer, int offset, long time) {
long seconds = time / 1000L;
long milliseconds = time - seconds * 1000L;
seconds += OFFSET_1900_TO_1970;
// write seconds in big endian format
buffer[offset++] = (byte)(seconds >> 24);
buffer[offset++] = (byte)(seconds >> 16);
buffer[offset++] = (byte)(seconds >> 8);
buffer[offset++] = (byte)(seconds >> 0);
long fraction = milliseconds * 0x100000000L / 1000L;
// write fraction in big endian format
buffer[offset++] = (byte)(fraction >> 24);
buffer[offset++] = (byte)(fraction >> 16);
buffer[offset++] = (byte)(fraction >> 8);
// low order bits should be random data
buffer[offset++] = (byte)(Math.random() * 255.0);
}
}
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