试试这个

String mytime = (DateFormat.format("dd-MM-yyyy hh:mm:ss", new java.util.Date()).toString());

如果你想以特定的模式获取日期和时间，你可以使用以下命令:

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault());
String currentDateandTime = sdf.format(new Date());

Or,

日期:

String currentDate = new SimpleDateFormat("dd-MM-yyyy", Locale.getDefault()).format(new Date());

时间:

String currentTime = new SimpleDateFormat("HH:mm:ss", Locale.getDefault()).format(new Date());

SimpleDateFormat databaseDateTimeFormate = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
SimpleDateFormat databaseDateFormate = new SimpleDateFormat("yyyy-MM-dd");
SimpleDateFormat sdf1 = new SimpleDateFormat("dd.MM.yy");
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy.MM.dd G 'at' hh:mm:ss z");
SimpleDateFormat sdf3 = new SimpleDateFormat("EEE, MMM d, ''yy");
SimpleDateFormat sdf4 = new SimpleDateFormat("h:mm a");
SimpleDateFormat sdf5 = new SimpleDateFormat("h:mm");
SimpleDateFormat sdf6 = new SimpleDateFormat("H:mm:ss:SSS");
SimpleDateFormat sdf7 = new SimpleDateFormat("K:mm a,z");
SimpleDateFormat sdf8 = new SimpleDateFormat("yyyy.MMMMM.dd GGG hh:mm aaa");


String currentDateandTime = databaseDateTimeFormate.format(new Date());     //2009-06-30 08:29:36
String currentDateandTime = databaseDateFormate.format(new Date());     //2009-06-30
String currentDateandTime = sdf1.format(new Date());     //30.06.09
String currentDateandTime = sdf2.format(new Date());     //2009.06.30 AD at 08:29:36 PDT
String currentDateandTime = sdf3.format(new Date());     //Tue, Jun 30, '09
String currentDateandTime = sdf4.format(new Date());     //8:29 PM
String currentDateandTime = sdf5.format(new Date());     //8:29
String currentDateandTime = sdf6.format(new Date());     //8:28:36:249
String currentDateandTime = sdf7.format(new Date());     //8:29 AM,PDT
String currentDateandTime = sdf8.format(new Date());     //2009.June.30 AD 08:29 AM

日期格式

G   Era designator (before christ, after christ)
y   Year (e.g. 12 or 2012). Use either yy or yyyy.
M   Month in year. Number of M's determine length of format (e.g. MM, MMM or MMMMM)
d   Day in month. Number of d's determine length of format (e.g. d or dd)
h   Hour of day, 1-12 (AM / PM) (normally hh)
H   Hour of day, 0-23 (normally HH)
m   Minute in hour, 0-59 (normally mm)
s   Second in minute, 0-59 (normally ss)
S   Millisecond in second, 0-999 (normally SSS)
E   Day in week (e.g Monday, Tuesday etc.)
D   Day in year (1-366)
F   Day of week in month (e.g. 1st Thursday of December)
w   Week in year (1-53)
W   Week in month (0-5)
a   AM / PM marker
k   Hour in day (1-24, unlike HH's 0-23)
K   Hour in day, AM / PM (0-11)
z   Time Zone

你可以(但不再应该-见下文!)使用android.text.format.Time:

Time now = new Time();
now.setToNow();

从上面的参考链接:

Time类是一个更快的替代品 为java.util.Calendar和 java.util.GregorianCalendar类。 Time类的实例 表示指定的时间点 精准度第二。

注1: 我写这个答案已经有好几年了， 它是关于一个旧的，android专用的，现在已被弃用的类。 谷歌现在这样说 “他的类有一些问题，建议使用公历代替”。

注2:尽管Time类有一个toMillis(ignoreDaylightSavings)方法，但这只是为了方便传递给以毫秒为单位的方法。时间值仅精确到一秒;毫秒部分总是000。如果在循环中，你会这样做

Time time = new Time();   time.setToNow();
Log.d("TIME TEST", Long.toString(time.toMillis(false)));
... do something that takes more than one millisecond, but less than one second ...

结果序列将重复相同的值，例如1410543204000，直到下一秒开始，此时1410543205000将开始重复。

实际上，使用time . getcurrenttimezone()在设备上设置当前时区更安全，否则您将获得UTC的当前时间。

Time today = new Time(Time.getCurrentTimezone());
today.setToNow();

然后，你可以得到你想要的所有日期字段，例如:

textViewDay.setText(today.monthDay + "");             // Day of the month (1-31)
textViewMonth.setText(today.month + "");              // Month (0-11)
textViewYear.setText(today.year + "");                // Year 
textViewTime.setText(today.format("%k:%M:%S"));  // Current time

详情请参阅android.text.format.Time类。

更新

正如许多人指出的那样，谷歌说这个类有一些问题，不应该再使用了:

This class has a number of issues and it is recommended that GregorianCalendar is used instead. Known issues: For historical reasons when performing time calculations all arithmetic currently takes place using 32-bit integers. This limits the reliable time range representable from 1902 until 2037.See the wikipedia article on the Year 2038 problem for details. Do not rely on this behavior; it may change in the future. Calling switchTimezone(String) on a date that cannot exist, such as a wall time that was skipped due to a DST transition, will result in a date in 1969 (i.e. -1, or 1 second before 1st Jan 1970 UTC). Much of the formatting / parsing assumes ASCII text and is therefore not suitable for use with non-ASCII scripts.

在com.google.gson.internal.bind.util包中有一个ISO8601Utils实用程序类，所以如果你在你的应用程序中使用Gson，你可以使用它。

它支持毫秒和时区，所以这是一个很好的开箱即用的选择。