Content Viewer for Android development

Content Observer:

When the database data of the application is changed, the content provider notifies the content provider to register a content observer on the URI, and can receive notification of changes to the data.

Implementation steps:

1. If it is a custom contentprovider, the following code needs to be implemented in the method of data transmission change:

1 contentresolver cr = getcontext (). Getcontentresolver (); 2 // notification that all content observers registered on this URI can be notified 3 null);

Notifychange (URI URI, contentobserver observer)//parameter Uri: uri//parameter for content send change Observer: can be NULL if specified as a content observer, a bit similar to the final receiver of the broadcast ; If you register the content observer, true 2. Register a content watcher where you want to accept the data change notification

1 Importandroid.app.Activity;2 ImportAndroid.content.ContentResolver;3 ImportAndroid.database.ContentObserver;4 ImportAndroid.net.Uri;5 ImportAndroid.os.Bundle;6 ImportAndroid.os.Handler;7 8  Public classMainactivityextendsActivity {9 Ten @Override One     protected voidonCreate (Bundle savedinstancestate) { A         Super. OnCreate (savedinstancestate); - Setcontentview (r.layout.activity_main); - Initlinstener (); the     } -  -     Private voidInitlinstener () { -Contentresolver cr=getcontentresolver (); +Cr.registercontentobserver (Uri.parse ("Content://sms"),true,NewMyobserver (NewHandler ())); -     } +      A     classMyobserverextendscontentobserver{ at  -          Publicmyobserver (Handler Handler) { -             Super(handler); -         } -         //This method is called when the content watcher receives a notification that the database has changed - @Override in          Public voidOnChange (BooleanSelfchange) { -             Super. OnChange (selfchange); toSYSTEM.OUT.PRINTLN ("SMS Database send changes! "); +         } -     } the      *}

Registercontentobserver (Uri Uri, Boolean notifyfordescendents, Contentobserver observer)

Parameter URI: listens to which URI the content provider's notice//parameter notifyfordescendents:false, need to match exactly, when true, need to be the URI that starts with the URI data changes, can receive the notification// Parameter Observer: The object of the callback when sending the change needs to implement a myobserver to implement Contentobserver. and implement the OnChange () method in the class.

Content Viewer for Android development