Java获取UTC时间的方法详解

java.util.Calendar cal = java.util.Calendar.getInstance();

java.util.TimeZone zone = java.util.TimeZone.getTimeZone(“GMT-8:00″);
java.util.Calendar cal = java.util.Calendar.getInstance(zone);
java.util.Calendar cal = java.util.Calendar.getInstance(java.util.Locale.CHINA);

java.util.Calendar cal = java.util.Calendar.getInstance();

int zoneOffset = cal.get(java.util.Calendar.ZONE_OFFSET);

int dstOffset = cal.get(java.util.Calendar.DST_OFFSET);

cal.add(java.util.Calendar.MILLISECOND, -(zoneOffset + dstOffset));

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.TimeZone;
public final class GetUTCTimeUtil {
  private static DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm") ;
  /**
   * 得到UTC时间，类型为字符串，格式为"yyyy-MM-dd HH:mm"<br />
   * 如果获取失败，返回null
   * @return
   */
  public static String getUTCTimeStr() {
    StringBuffer UTCTimeBuffer = new StringBuffer();
    // 1、取得本地时间：
    Calendar cal = Calendar.getInstance() ;
    // 2、取得时间偏移量：
    int zoneOffset = cal.get(java.util.Calendar.ZONE_OFFSET);
    // 3、取得夏令时差：
    int dstOffset = cal.get(java.util.Calendar.DST_OFFSET);
    // 4、从本地时间里扣除这些差量，即可以取得UTC时间：
    cal.add(java.util.Calendar.MILLISECOND, -(zoneOffset + dstOffset));
    int year = cal.get(Calendar.YEAR);
    int month = cal.get(Calendar.MONTH)+1;
    int day = cal.get(Calendar.DAY_OF_MONTH);
    int hour = cal.get(Calendar.HOUR_OF_DAY);
    int minute = cal.get(Calendar.MINUTE);
    UTCTimeBuffer.append(year).append("-").append(month).append("-").append(day) ;
    UTCTimeBuffer.append(" ").append(hour).append(":").append(minute) ;
    try{
      format.parse(UTCTimeBuffer.toString()) ;
      return UTCTimeBuffer.toString() ;
    }catch(ParseException e)
    {
      e.printStackTrace() ;
    }
    return null ;
  }
  /**
   * 将UTC时间转换为东八区时间
   * @param UTCTime
   * @return
   */
  public static String getLocalTimeFromUTC(String UTCTime){
    java.util.Date UTCDate = null ;
    String localTimeStr = null ;
    try {
      UTCDate = format.parse(UTCTime);
      format.setTimeZone(TimeZone.getTimeZone("GMT-8")) ;
      localTimeStr = format.format(UTCDate) ;
    } catch (ParseException e) {
      e.printStackTrace();
    }
    return localTimeStr ;
  }
  public static void main(String[] args) {
    String UTCTimeStr = getUTCTimeStr() ;
    System.out.println(UTCTimeStr);
    System.out.println(getLocalTimeFromUTC(UTCTimeStr));
  }
}