SystemUI上的时间显示只要就在/frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/policy/Clock.java类上

效果图

这个类也很简单，监听处理广播

@Override

protected void onAttachedToWindow() {

super.onAttachedToWindow();

if (!mAttached) {

mAttached = true;

IntentFilter filter = new IntentFilter();

filter.addAction(Intent.ACTION_TIME_TICK);

filter.addAction(Intent.ACTION_TIME_CHANGED);

filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);

filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);

filter.addAction(Intent.ACTION_USER_SWITCHED);

getContext().registerReceiver(mIntentReceiver, filter, null,

getHandler());

}

// NOTE: It's safe to do these after registering the receiver since the

// receiver always runs

// in the main thread, therefore the receiver can't run before this

// method returns.

// The time zone may have changed while the receiver wasn't registered,

// so update the Time

mCalendar = Calendar.getInstance(TimeZone.getDefault());

// Make sure we update to the current time

updateClock();

}

@Override

protected void onDetachedFromWindow() {

super.onDetachedFromWindow();

if (mAttached) {

getContext().unregisterReceiver(mIntentReceiver);

mAttached = false;

}

}在广播中去更新时间和监听语言是否有改变

private final BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {

@Override

public void onReceive(Context context, Intent intent) {

String action = intent.getAction();

Log.d(TAG, "action =" + action);

if (action.equals(Intent.ACTION_TIMEZONE_CHANGED)) {

String tz = intent.getStringExtra("time-zone");

mCalendar = Calendar.getInstance(TimeZone.getTimeZone(tz));

if (mClockFormat != null) {

mClockFormat.setTimeZone(mCalendar.getTimeZone());

}

Log.d(TAG,

"mCalendar =" + mCalendar

+ "TimeZone.getTimeZone(tz) ="

+ TimeZone.getTimeZone(tz));

} else if (action.equals(Intent.ACTION_CONFIGURATION_CHANGED)) {

final Locale newLocale = getResources().getConfiguration().locale;

if (!newLocale.equals(mLocale)) {

mLocale = newLocale;

mClockFormatString = ""; // force refresh

}

}

updateClock();

}

};在设置中可以改变时间显示是以12小时还是24小时

时间的格式合成都是在这个函数中完成

private final CharSequence getSmallTime() {

Context context = getContext();

boolean is24 = DateFormat.is24HourFormat(context);

LocaleData d = LocaleData

.get(context.getResources().getConfiguration().locale);

final char MAGIC1 = '\uEF00';

final char MAGIC2 = '\uEF01';

SimpleDateFormat sdf;

String format = is24 ? d.timeFormat24 : d.timeFormat12;

if (!format.equals(mClockFormatString)) {

/*

* Search for an unquoted "a" in the format string, so we can add

* dummy characters around it to let us find it again after

* formatting and change its size.

*/

if (AM_PM_STYLE != AM_PM_STYLE_NORMAL) {

int a = -1;

boolean quoted = false;

for (int i = 0; i < format.length(); i++) {

char c = format.charAt(i);

if (c == '\'') {

quoted = !quoted;

}

if (!quoted && c == 'a') {

a = i;

break;

}

}

if (a >= 0) {

// Move a back so any whitespace before AM/PM is also in the

// alternate size.

final int b = a;

while (a > 0

&& Character.isWhitespace(format.charAt(a - 1))) {

a--;

}

format = format.substring(0, a) + MAGIC1

+ format.substring(a, b) + "a" + MAGIC2

+ format.substring(b + 1);

}

}

mClockFormat = sdf = new SimpleDateFormat(format);

mClockFormatString = format;

} else {

sdf = mClockFormat;

}

String result = sdf.format(mCalendar.getTime());

if (AM_PM_STYLE != AM_PM_STYLE_NORMAL) {

int magic1 = result.indexOf(MAGIC1);

int magic2 = result.indexOf(MAGIC2);

if (magic1 >= 0 && magic2 > magic1) {

SpannableStringBuilder formatted = new SpannableStringBuilder(

result);

if (AM_PM_STYLE == AM_PM_STYLE_GONE) {

formatted.delete(magic1, magic2 + 1);

} else {

if (AM_PM_STYLE == AM_PM_STYLE_SMALL) {

CharacterStyle style = new RelativeSizeSpan(0.7f);

formatted.setSpan(style, magic1, magic2,

Spannable.SPAN_EXCLUSIVE_INCLUSIVE);

}

formatted.delete(magic2, magic2 + 1);

formatted.delete(magic1, magic1 + 1);

}

return formatted;

}

}

return result;

}