本章节翻译自《Beginning-Android-4-Application-Development》,如有翻译不当的地方,敬请指出。
原书购买地址 http://www.amazon.com/Beginning-Android-4-Application-Development/dp/1118199545/
到目前为止,想必大家已经都熟悉使用Toast去给用户显示信息了。尽管使用Toast很方便,但是Toast显示的通知并不是永久存储的。它只在屏幕上显示一小段时间,然后就消失了。如果它包含一些特别重要的信息,如果用户没有观察屏幕,那么用户就很容易错过它。
对于那些重要的信息,应该采用一种更加持久保存的方法。在这种情况下,应该使用NotificationMnanger(消息管理器)去显示一个长久的信息,这个消息被显示在了StatusBar(状态栏)上面,使用用户能够很容易地看见。
接下来展示如何发送一个Notification通知。
1. 创建一个工程:Notifications。
2. 在包中新建一个名为NotificationView的类,同时在res/layout文件夹下面新建一个名为notification.xml 文件,它将作为NotificationView的视图。
3. notification.xml中的文件。
- <? xml version = "1.0" encoding = "utf-8" ?>
- < LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
- android:layout_width = "fill_parent"
- android:layout_height = "fill_parent"
- android:orientation = "vertical" >
- < TextView
- android:layout_width = "fill_parent"
- android:layout_height = "wrap_content"
- android:text = "Herearethedetailsforthenotification..." />
- </ LinearLayout >
4.NotificationView.java中的代码。
- public class NotificationView extends Activity{
- @Override
- public void onCreate(BundlesavedInstanceState){
- super .onCreate(savedInstanceState);
- setContentView(R.layout.notification);
- //---lookupthenotificationmanagerservice---
- NotificationManagernm=(NotificationManager)getSystemService(NOTIFICATION_SERVICE);
- //---cancelthenotificationthatwestarted---
- nm.cancel(getIntent().getExtras().getInt( "notificationID" ));
- }
- }
5. AndroidManifest.xml中的代码。
- <? xml version = "1.0" encoding = "utf-8" ?>
- < manifest xmlns:android = "http://schemas.android.com/apk/res/android"
- package = "net.learn2develop.Notifications"
- android:versionCode = "1"
- android:versionName = "1.0" >
- < uses-sdk android:minSdkVersion = "14" />
- < uses-permission android:name = "android.permission.VIBRATE" />
- < application
- android:icon = "@drawable/ic_launcher"
- android:label = "@string/app_name" >
- < activity
- android:label = "@string/app_name"
- android:name = ".NotificationsActivity" >
- < intent-filter >
- < action android:name = "android.intent.action.MAIN" />
- < category android:name = "android.intent.category.LAUNCHER" />
- </ intent-filter >
- </ activity >
- < activity android:name = ".NotificationView"
- android:label = "Detailsofnotification" >
- < intent-filter >
- < action android:name = "android.intent.action.MAIN" />
- < category android:name = "android.intent.category.DEFAULT" />
- </ intent-filter >
- </ activity >
- </ application >
- </ manifest >
- <? xml version = "1.0" encoding = "utf-8" ?>
- < LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
- android:layout_width = "fill_parent"
- android:layout_height = "fill_parent"
- android:orientation = "vertical" >
- < Button
- android:id = "@+id/btn_displaynotif"
- android:layout_width = "fill_parent"
- android:layout_height = "wrap_content"
- android:text = "DisplayNotification"
- android:onClick = "onClick" />
- </ LinearLayout >
- public class NotificationsActivity extends Activity{
- int notificationID= 1 ;
- /**Calledwhentheactivityisfirstcreated.*/
- @Override
- public void onCreate(BundlesavedInstanceState){
- super .onCreate(savedInstanceState);
- setContentView(R.layout.main);
- }
- public void onClick(Viewview){
- displayNotification();
- }
- protected void displayNotification()
- {
- //---PendingIntenttolaunchactivityiftheuserselects
- //thisnotification---
- Intenti= new Intent( this ,NotificationView. class );
- i.putExtra( "notificationID" ,notificationID);
- PendingIntentpendingIntent=
- PendingIntent.getActivity( this , 0 ,i, 0 );
- NotificationManagernm=(NotificationManager)
- getSystemService(NOTIFICATION_SERVICE);
- Notificationnotif= new Notification(
- R.drawable.ic_launcher,
- "Reminder:Meetingstartsin5minutes" ,
- System.currentTimeMillis());
- CharSequencefrom= "SystemAlarm" ;
- CharSequencemessage= "Meetingwithcustomerat3pm..." ;
- notif.setLatestEventInfo( this ,from,message,pendingIntent);
- //---100msdelay,vibratefor250ms,pausefor100msand
- //thenvibratefor500ms---
- notif.vibrate= new long []{ 100 , 250 , 100 , 500 };
- nm.notify(notificationID,notif);
- }
- }
9. 点击Display Notification按钮,在状态栏上面就会出现一个notification通知。如图:
10.将状态栏拉下来,就会显示这个Notification通知的详尽信息。如图:
11. 点击这个Notification通知,就会显示NotificationView的界面,同时,状态栏上面的通知也消失了。如图: