Transcript Android UI Develop and Design

ANDROID
CONTENT PROVIDERS
Peter Liu
School of ICT, Seneca College
Android Content Providers
• Why?
• What?
• How to access a built-in Android content
provider?
• How to create (and access) a content provider?
• Lab Exercise
Android Concept of a Content Provider
• Persistent data sharing among Android applications
• SQLite database
• private to an Android app
• accessible to one Java package
• Question: How to make it accessible to other Android
apps/Java packages?
What is a Content Provider?
• A standard interface for connecting data in one process
with another process
• http://developer.android.com/guide/topics/providers/content-
providers.html (Android for Developers)
• Two diagrams (Figures 4-4, 4-5 in Learning Android)
• http://libcat.senecacollege.ca/vwebv/holdingsInfo?searchId=38206
&recCount=50&recPointer=1&bibId=315195
• Demo (the Contacts Provider)
• a built-in Android content provider
• Further Exploration
• http://developer.android.com/guide/topics/providers/contactsprovider.html (Android for Developers)
How to access the Contacts provider?
• Concepts: URI, relational tables, SQL statements
• Code Walkthrough (with my comments)
• use a ContentResolver client object
• Invoke CRUD (create, retrieve, update, and delete) methods
• display query results (or getting data from query results)
• request permissions in the manifest file
• CursorLoader
• asynchronous loading of data (i.e. a separate thread)
Content URI (Uniform Resource Identifier)
• Concept: identification of data in a content provider
• all the data in a table
• a row in a table
• Examples
• “content://call_log/calls”
• “content://contacts/people”
• Syntax (textbook)
• <standard prefix>://<authority>/<data path>/<id>
• <authority>: contacts
• <data path>: people
• API Exploration
• http://developer.android.com/reference/android/provider/CallLog.html
How to create a content provider?
• Demo (the Books Provider)
• Procedure (4 steps from Learning Android)
• Create a Java class that is a subclass of the system’s
ContentProvider class.
• Declare the CONTENT_URI.
• Implement the CRUD methods and getType() method.
• Declare the content provider in the manifest file.
• Code Walkthrough (3 Java classes)
• Further Exploration
• course wiki:
http://zenit.senecac.on.ca/wiki/index.php/Resources_for_Learning_
Android_App_Development