It's Working

调用这个方法，在你使用

SntpClient client = new SntpClient();
if (client.requestTime("ntp.ubuntu.com", 30000)) {
  long now = client.getNtpTime();
  Date current = new Date(now);
  date2 = sdf.parse(new Date(current.getTime()).toString());
 // System.out.println(current.toString());
  Log.e(TAG, "testing SntpClient time current.toString() "+current.toString()+" , date2 = "+date2);
=====================================================   
import android.os.SystemClock;
import android.util.Log;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 * {@hide}
 * Simple SNTP client class for retrieving network time.
 * Sample usage:
 * <pre>SntpClient client = new SntpClient();
 * if (client.requestTime("time.foo.com")) {
 *     long now = client.getNtpTime() + SystemClock.elapsedRealtime() - client.getNtpTimeReference();
 * </pre>
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);
      // 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;
   * 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);