【直接拿来用のandroid公共代码模块解析与分享】の Notification和NotificationManager

本文源代码托管在https://github.com/ASCE1885/asce-common，欢迎fork

Android项目做得多了。会发现原来非常多基础的东西都是能够复用，这个系列介绍一些自己项目中经常使用到的公共模块代码（当然仅仅谈技术不谈业务），一来整理好了自己以后能够直接用，二来也分享给大家，希望能略微降低大家的加班时间，提高些许效率。

Android Notification的原理和作用这里就不作说明了，相信是个android开发人员都用过不止一次了，下面仅仅介绍怎样封装成公共的模块。以供整个项目使用。

基于不同的目的。Notification的外观区别非常大，相应到代码上就是布局的差异，因此。我们首先须要有一个接口供使用者来创建不同布局的Notification，接口在Java中当然是以Interface的形式存在。如代码清单IMyNotificationBuilder.java所看到的。

/**
 * Notification接口
 *
 * @author asce1885
 * @date 2014-06-09
 *
 */
public interface IMyNotificationBuilder {

	public static final String NOTIFICATION_ID = IMyNotificationBuilder.class.getSimpleName();

	Notification buildNotification(String title, String content);

}

看到这里，熟悉设计模式的同学应该知道我们使用的是Builder模式来构建不同的Notification，依照惯例，一般会有一个默认的Builder实现，我们将之命名为BasicNotificationBuilder.java。它使用的是Android系统默认的通知栏布局。

/**
 * 默认Notification构造器
 *
 * @author asce1885
 * @date 2014-06-09
 *
 */
public class BasicNotificationBuilder implements IMyNotificationBuilder {

	private Context mContext;
	private PendingIntent mPendingIntent;

	public int mIconDrawableId;

	public BasicNotificationBuilder(Context context, PendingIntent pendingIntent) {
		mContext = context;
		mPendingIntent = pendingIntent;
		mIconDrawableId = PackageUtils.getAppInfo(context).icon;
	}

	public BasicNotificationBuilder(Context context, PendingIntent pendingIntent, int iconDrawableId) {
		mContext = context;
		mPendingIntent = pendingIntent;
		mIconDrawableId = iconDrawableId;
	}

	@SuppressWarnings("deprecation")
	@Override
	public Notification buildNotification(String title, String content) {
		Notification basicNotification = new Notification(mIconDrawableId, title,
				System.currentTimeMillis());
		basicNotification.setLatestEventInfo(mContext, title, content, mPendingIntent);
		basicNotification.flags |= Notification.FLAG_AUTO_CANCEL;
		basicNotification.defaults = Notification.DEFAULT_SOUND;
		basicNotification.contentIntent = mPendingIntent;

		return basicNotification;
	}

}

对于其它须要自己定义布局的通知栏形式。我们另外实现一个类。布局文件由使用者自己定义，见代码清单CustomNotificationBuilder.java。

/**
 * 自己定义样式Notification构造器
 *
 * @author asce1885
 * @date 2014-06-09
 *
 */
public class CustomNotificationBuilder implements IMyNotificationBuilder {

	private Context mContext;
	private int mCustomeLayout;
	private int mLayoutSubjectId;
	private int mLayoutMessageId;
	private int mLayoutIconId;
	private int mStatusBarIconDrawableId;
	private Uri mSoundUri;
	private PendingIntent mPendingIntent;

	public CustomNotificationBuilder(Context context, int customeLayout, int layoutSubjectId, int layoutMessageId, int layoutIconId, int statusBarIconDrawableId, Uri soundUri, PendingIntent pendingIntent) {
		mContext = context;
		mCustomeLayout = customeLayout;
		mLayoutSubjectId = layoutSubjectId;
		mLayoutMessageId = layoutMessageId;
		mLayoutIconId = layoutIconId;
		mStatusBarIconDrawableId = statusBarIconDrawableId;
		mSoundUri = soundUri;
		mPendingIntent = pendingIntent;
	}

	@SuppressWarnings("deprecation")
	@Override
	public Notification buildNotification(String title, String content) {
		if (TextUtils.isEmpty(content)) {
			return null;
		}

		PreFroyoNotificationStyleDiscover.getInstance().discoverStyle(mContext);

		Notification customerNotification = new Notification(mStatusBarIconDrawableId, title,
				System.currentTimeMillis());
		RemoteViews customerRemoteView = new RemoteViews(mContext.getPackageName(), mCustomeLayout);
		customerRemoteView.setTextViewText(mLayoutSubjectId, PackageUtils.getAppName(mContext));
		customerRemoteView.setTextViewText(mLayoutMessageId, content);
		customerRemoteView.setImageViewResource(mLayoutIconId, mStatusBarIconDrawableId);
		customerNotification.flags |= Notification.FLAG_AUTO_CANCEL;

		if (mSoundUri != null) {
			customerNotification.sound = mSoundUri;
		} else {
			customerNotification.defaults = Notification.DEFAULT_SOUND;
		}
		customerNotification.contentIntent = mPendingIntent;

		// Some SAMSUNG devices status bar cant't show two lines with the size,
		// so need to verify it, maybe increase the height or decrease the font size

		customerRemoteView.setFloat(mLayoutSubjectId, "setTextSize",
				PreFroyoNotificationStyleDiscover.getInstance().getTitleSize());
		customerRemoteView.setTextColor(mLayoutSubjectId, PreFroyoNotificationStyleDiscover
				.getInstance().getTitleColor());

		customerRemoteView.setFloat(mLayoutMessageId, "setTextSize",
				PreFroyoNotificationStyleDiscover.getInstance().getTextSize());
		customerRemoteView.setTextColor(mLayoutMessageId, PreFroyoNotificationStyleDiscover
				.getInstance().getTextColor());

		customerNotification.contentView = customerRemoteView;

		return customerNotification;
	}

	/**
	 * A class for discovering Android Notification styles on Pre-Froyo (2.3) devices
	 */
	private static class PreFroyoNotificationStyleDiscover {

		private Integer mNotifyTextColor = null;
		private float mNotifyTextSize = 11;
		private Integer mNotifyTitleColor = null;
		private float mNotifyTitleSize = 12;
		private final String TEXT_SEARCH_TEXT = "SearchForText";
		private final String TEXT_SEARCH_TITLE = "SearchForTitle";

		private static Context mContext;

		private static class LazyHolder {
			private static final PreFroyoNotificationStyleDiscover sInstance = new PreFroyoNotificationStyleDiscover();
		}

		public static PreFroyoNotificationStyleDiscover getInstance() {
			return LazyHolder.sInstance;
		}

		private PreFroyoNotificationStyleDiscover() {

		}

		public int getTextColor() {
			return mNotifyTextColor.intValue();
		}

		public float getTextSize() {
			return mNotifyTextSize;
		}

		public int getTitleColor() {
			return mNotifyTitleColor;
		}

		public float getTitleSize() {
			return mNotifyTitleSize;
		}

		private void discoverStyle(Context context) {
			mContext = context;
			// Already done
			if (null != mNotifyTextColor) {
				return;
			}

			try {
				Notification notify = new Notification();
				notify.setLatestEventInfo(mContext, TEXT_SEARCH_TITLE, TEXT_SEARCH_TEXT, null);
				LinearLayout group = new LinearLayout(mContext);
				ViewGroup event = (ViewGroup) notify.contentView.apply(mContext, group);
				recurseGroup(event);
				group.removeAllViews();
			} catch (Exception e) {
				// Default to something
				mNotifyTextColor = android.R.color.black;
				mNotifyTitleColor = android.R.color.black;
			}
		}

		private boolean recurseGroup(ViewGroup group) {
			final int count = group.getChildCount();

			for (int i = 0; i < count; ++i) {
				if (group.getChildAt(i) instanceof TextView) {
					final TextView tv = (TextView) group.getChildAt(i);
					final String text = tv.getText().toString();
					if (text.startsWith("SearchFor")) {
						DisplayMetrics metrics = new DisplayMetrics();
						WindowManager wm = (WindowManager) mContext
								.getSystemService(Context.WINDOW_SERVICE);
						wm.getDefaultDisplay().getMetrics(metrics);

						if (TEXT_SEARCH_TEXT == text) {
							mNotifyTextColor = tv.getTextColors().getDefaultColor();
							mNotifyTextSize = tv.getTextSize();
							mNotifyTextSize /= metrics.scaledDensity;
						} else {
							mNotifyTitleColor = tv.getTextColors().getDefaultColor();
							mNotifyTitleSize = tv.getTextSize();
							mNotifyTitleSize /= metrics.scaledDensity;
						}

						if (null != mNotifyTitleColor && mNotifyTextColor != null) {
							return true;
						}
					}
				} else if (group.getChildAt(i) instanceof ViewGroup) {
					if (recurseGroup((ViewGroup) group.getChildAt(i))) {
						return true;
					}
				}
			}
			return false;
		}
	}

}

Notification的构建代码至此结束。而要发出Notification，使用的是NotificationManager，我们将它封装成代码清单MyNotificationManager.java。

/**
 * Notification管理器
 *
 * @author asce1885
 * @date 2014-06-09
 *
 */
public class MyNotificationManager {

	private IMyNotificationBuilder mMyNotificationBuilder;

	private static final int START_ID = 1000;
	private static final int RANGE = 50;
	private int mCurrentId = START_ID;

	private MyNotificationManager() {

	}

	private static class LazyHolder {
		private static final MyNotificationManager sInstance = new MyNotificationManager();
	}

	public static MyNotificationManager getInstance() {
		return LazyHolder.sInstance;
	}

	public IMyNotificationBuilder getMyNotificationBuilder() {
		return mMyNotificationBuilder;
	}

	public void setMyNotificationBuilder(IMyNotificationBuilder builder) {
		mMyNotificationBuilder = builder;
	}

	public void deliverNotification(Context context, String title, String content) {
		buildAndDisplayNotification(context, title, content);
	}

	private void buildAndDisplayNotification(Context context, String title, String content) {
		if (null != mMyNotificationBuilder) {
			Notification notification = mMyNotificationBuilder.buildNotification(title, content);
			if (null != notification) {
				notification.flags |= Notification.FLAG_AUTO_CANCEL;
				NotificationManager notificationManager = (NotificationManager) context
						.getSystemService(Context.NOTIFICATION_SERVICE);
				notificationManager.notify(generateNotification(), notification);
			}
		}
	}

	private int generateNotification() {
		mCurrentId++;
		if (mCurrentId >= START_ID + RANGE) {
			mCurrentId = START_ID;
		}
		return mCurrentId;
	}
}

最后给下使用的演示样例代码例如以下所看到的，仅仅作为參考。里面的部分变量不用深究。

				Intent intent = new Intent(getApplicationContext(), MainActivity.class);
				intent.putExtra(BundleConstant.KEY_NOTIFICATION_TYPE, action);
				intent.putExtra(BundleConstant.KEY_WEBVIEW_TITLE, notice.webview_title);
				intent.putExtra(BundleConstant.KEY_WEBVIEW_URL, notice.webview_url);
				PendingIntent pendingIntent = PendingIntent.getActivity(getApplicationContext(), (int) notice.nid, intent, PendingIntent.FLAG_UPDATE_CURRENT);

				builder = new BasicNotificationBuilder(getApplicationContext(), pendingIntent);
				MyNotificationManager.getInstance().setMyNotificationBuilder(builder);
				MyNotificationManager.getInstance().deliverNotification(getApplicationContext(), notice.notification_title, notice.notification_content);

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