Create a Content Provider in Android

Introduction

 
In this article I explain what a content provider is. A content provider is a collection of information of which a provider uses a way to access itself using another application. For example Contacts is a content provider because whenever we text a message, we want to import a number from the contact, then the contact provides us access to itself through another app, smsApplication. But in this article I create my own content provider that will provide all the content that will be available in this content provider, as described in the following procedure.
 
Step 1
 
Create a new project as "File" -> "New" -> "Android Application Project" as shown below.
 
Content_provider.jpg
 
Step 2
 
Now open the XML file  "res/layout/activity_main.xml" and update it as in the following code.
  1. <?xml version="1.0" encoding="utf-8"?>  
  2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
  3.    android:orientation="vertical"  
  4.    android:layout_width="fill_parent"  
  5.    android:layout_height="fill_parent" >  
  6.    <TextView   
  7.       android:layout_width="fill_parent"  
  8.       android:layout_height="wrap_content"  
  9.       android:text="ISBN" />  
  10.    <EditText  
  11.       android:id="@+id/txtISBN"   
  12.       android:layout_height="wrap_content"  
  13.       android:layout_width="fill_parent" />  
  14.    <TextView   
  15.       android:layout_width="fill_parent"  
  16.       android:layout_height="wrap_content"  
  17.       android:text="Title" />  
  18.    <EditText  
  19.       android:id="@+id/txtTitle"  
  20.       android:layout_height="wrap_content"  
  21.       android:layout_width="fill_parent" />  
  22.    <Button  
  23.       android:text="Add title"  
  24.       android:id="@+id/btnAdd"  
  25.       android:layout_width="fill_parent"  
  26.       android:layout_height="wrap_content" />     
  27.    <Button  
  28.       android:text="Retrieve titles"  
  29.       android:id="@+id/btnRetrieve"  
  30.       android:layout_width="fill_parent"  
  31.       android:layout_height="wrap_content" />     
  32. </LinearLayout> 
     
Step 3
 
Open Java from "src/com.newandroid.project/MainActivity.java" and update it with the following code.
  1. package com.content_provider;  
  2. import android.app.Activity;  
  3. import android.os.Bundle;  
  4. import android.util.Log;  
  5. import android.view.View;  
  6. import android.widget.Button;  
  7. import android.widget.EditText;  
  8. import android.widget.ListView;  
  9. import android.widget.Toast;  
  10. import android.content.ContentValues;  
  11. import android.database.Cursor;  
  12. import android.net.Uri;  
  13. public class MainActivity extends Activity {  
  14.     /** Called when the activity is first created. */  
  15.       ListView lv;  
  16.     @Override  
  17.     public void onCreate(Bundle savedInstanceState) {  
  18.         super.onCreate(savedInstanceState);  
  19.         setContentView(R.layout.activity_main);  
  20.         ContentValues editedValues = new ContentValues();  
  21.         editedValues.put(ContentDiary.TITLE, "Android Tips and Tricks");         
  22.         getContentResolver().update(  
  23.             Uri.parse(  
  24.                 "content://com.ContentDiary.provider.books/books/2"),  
  25.             editedValues,  
  26.             null,  
  27.             null);  
  28.         getContentResolver().delete(  
  29. Uri.parse("content://com.ContentDiary.provider.books/books/2"),  
  30.                 nullnull);  
  31.         getContentResolver().delete(  
  32.                 Uri.parse("content://com.ContentDiary.provider.books/books"),  
  33.                 nullnull);  
  34.         ListView lv=(ListView) findViewById(R.id.view);  
  35.         Button btnAdd = (Button) findViewById(R.id.btnAdd);  
  36.         btnAdd.setOnClickListener(new View.OnClickListener() {  
  37.             public void onClick(View v) {  
  38.               ContentValues values = new ContentValues();  
  39.               values.put("title", ((EditText) findViewById(R.id.txtTitle)).getText().toString());  
  40.               values.put("isbn", ((EditText) findViewById(R.id.txtISBN)).getText().toString());         
  41.               Uri uri = getContentResolver().insert(  
  42. Uri.parse("content://com.ContentDiary.provider.books/books"),  
  43.                       values);  
  44.               Toast.makeText(getBaseContext(),uri.toString(), Toast.LENGTH_LONG).show();  
  45.           }  
  46.         });         
  47.         Button btnRetrieve = (Button) findViewById(R.id.btnRetrieve);  
  48.         btnRetrieve.setOnClickListener(new View.OnClickListener() {  
  49.             public void onClick(View v) {             
  50.                 //---retrieve the titles---  
  51.                 Uri allTitles = Uri.parse(  
  52.                     "content://com.ContentDiary.provider.books/books");  
  53.                 Cursor c = managedQuery(allTitles, nullnullnull"title desc");  
  54.                 if (c.moveToFirst()) {  
  55.                     do{  
  56.                         Log.d("ContentProviders",  
  57.                             c.getString(c.getColumnIndex(  
  58.                                 ContentDiary._ID)) + ", " +                      
  59.                             c.getString(c.getColumnIndex(  
  60.                                 ContentDiary.TITLE)) + ", " +                      
  61.                             c.getString(c.getColumnIndex(  
  62.                                 ContentDiary.ISBN)));                
  63.                     } while (c.moveToNext());  
  64.                 }  
  65.             }  
  66.         });  
  67.     }  
Step 5
 
Create a new Java file "ContentDairy.java" as "src/com.content_provider/ContentDairy.java" and update it using the following code.
  1. package com.content_provider;  
  2. import android.content.ContentProvider;  
  3. import android.content.ContentUris;  
  4. import android.content.ContentValues;  
  5. import android.content.Context;  
  6. import android.content.UriMatcher;  
  7. import android.database.Cursor;  
  8. import android.database.SQLException;  
  9. import android.database.sqlite.SQLiteDatabase;  
  10. import android.database.sqlite.SQLiteOpenHelper;  
  11. import android.database.sqlite.SQLiteQueryBuilder;  
  12. import android.net.Uri;  
  13. import android.text.TextUtils;  
  14. import android.util.Log;  
  15. public class ContentDiary extends ContentProvider  
  16. {  
  17.     public static final String PROVIDER_NAME =  
  18.         "com.ContentDiary.provider.books";  
  19.     public static final Uri CONTENT_URI =  
  20.         Uri.parse("content://"+ PROVIDER_NAME + "/books");  
  21.     public static final String _ID = "_id";  
  22.     public static final String TITLE = "title";  
  23.     public static final String ISBN = "isbn";  
  24.     private static final int BOOKS = 1;  
  25.     private static final int BOOK_ID = 2;     
  26.     private static final UriMatcher uriMatcher;  
  27.     static{  
  28.         uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);  
  29.         uriMatcher.addURI(PROVIDER_NAME, "books", BOOKS);  
  30.         uriMatcher.addURI(PROVIDER_NAME, "books/#", BOOK_ID);         
  31.     }  
  32.     //---for database use---  
  33.     private SQLiteDatabase booksDB;  
  34.     private static final String DATABASE_NAME = "Books";  
  35.     private static final String DATABASE_TABLE = "titles";  
  36.     private static final int DATABASE_VERSION = 1;  
  37.     private static final String DATABASE_CREATE =  
  38.             "create table " + DATABASE_TABLE +  
  39.             " (_id integer primary key autoincrement, "  
  40.             + "title text not null, isbn text not null);";  
  41.     private static class DatabaseHelper extends SQLiteOpenHelper  
  42.     {  
  43.         DatabaseHelper(Context context) {  
  44.             super(context, DATABASE_NAME, null, DATABASE_VERSION);  
  45.         }  
  46.         @Override  
  47.         public void onCreate(SQLiteDatabase db)  
  48.         {  
  49.             db.execSQL(DATABASE_CREATE);  
  50.         }  
  51.         @Override  
  52.         public void onUpgrade(SQLiteDatabase db, int oldVersion,  
  53.         int newVersion) {  
  54.             Log.w("Content provider database",  
  55.                   "Upgrading database from version " +  
  56.                   oldVersion + " to " + newVersion +  
  57.                   ", which will destroy all old data");  
  58.             db.execSQL("DROP TABLE IF EXISTS titles");  
  59.             onCreate(db);  
  60.         }  
  61.     }  
  62.     @Override  
  63.     public int delete(Uri arg0, String arg1, String[] arg2) {  
  64.         // arg0 = uri  
  65.         // arg1 = selection  
  66.         // arg2 = selectionArgs  
  67.         int count=0;  
  68.         switch (uriMatcher.match(arg0)){  
  69.             case BOOKS:  
  70.                 count = booksDB.delete(  
  71.                         DATABASE_TABLE,  
  72.                         arg1,  
  73.                         arg2);  
  74.                 break;  
  75.             case BOOK_ID:  
  76.                 String id = arg0.getPathSegments().get(1);  
  77.                 count = booksDB.delete(  
  78.                         DATABASE_TABLE,                         
  79.                         _ID + " = " + id +  
  80.                         (!TextUtils.isEmpty(arg1) ? " AND (" +  
  81.                                 arg1 + ')' : ""),  
  82.                                 arg2);  
  83.                 break;  
  84.             defaultthrow new IllegalArgumentException("Unknown URI " + arg0);     
  85.         }        
  86.         getContext().getContentResolver().notifyChange(arg0, null);  
  87.         return count;  
  88.     }  
  89.    
  90.     @Override  
  91.     public String getType(Uri uri) {  
  92.         switch (uriMatcher.match(uri)){  
  93.             //---get all books---  
  94.             case BOOKS:  
  95.                 return "vnd.android.cursor.dir/vnd.learn2develop.books ";  
  96.             //---get a particular book---  
  97.             case BOOK_ID:                 
  98.                 return "vnd.android.cursor.item/vnd.learn2develop.books ";  
  99.             default:  
  100.                 throw new IllegalArgumentException("Unsupported URI: " + uri);         
  101.         }  
  102.     }  
  103.     @Override  
  104.     public Uri insert(Uri uri, ContentValues values) {  
  105.         //---add a new book---  
  106.         long rowID = booksDB.insert(  
  107.             DATABASE_TABLE,  
  108.             "",  
  109.             values);  
  110.          
  111.         //---if added successfully---  
  112.         if (rowID>0)  
  113.         {  
  114.             Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);  
  115.             getContext().getContentResolver().notifyChange(_uri, null);     
  116.             return _uri;                 
  117.         }         
  118.         throw new SQLException("Failed to insert row into " + uri);  
  119.     }  
  120.     @Override  
  121.     public boolean onCreate() {  
  122.         Context context = getContext();  
  123.         DatabaseHelper dbHelper = new DatabaseHelper(context);  
  124.         booksDB = dbHelper.getWritableDatabase();  
  125.         return (booksDB == null)? false:true;  
  126.     }  
  127.     @Override  
  128.     public Cursor query(Uri uri, String[] projection, String selection,  
  129.             String[] selectionArgs, String sortOrder) {  
  130.         SQLiteQueryBuilder sqlBuilder = new SQLiteQueryBuilder();  
  131.         sqlBuilder.setTables(DATABASE_TABLE);  
  132.         if (uriMatcher.match(uri) == BOOK_ID)  
  133.             //---if getting a particular book---  
  134.             sqlBuilder.appendWhere(  
  135.                 _ID + " = " + uri.getPathSegments().get(1));                 
  136.         if (sortOrder==null || sortOrder=="")  
  137.             sortOrder = TITLE;  
  138.         Cursor c = sqlBuilder.query(  
  139.                 booksDB,  
  140.                 projection,  
  141.                 selection,  
  142.                 selectionArgs,  
  143.                 null,  
  144.                 null,  
  145.                 sortOrder);  
  146.         //---register to watch a content URI for changes---  
  147.         c.setNotificationUri(getContext().getContentResolver(), uri);  
  148.         return c;  
  149.     }  
  150.     @Override  
  151.     public int update(Uri uri, ContentValues values, String selection,  
  152.             String[] selectionArgs) {  
  153.         int count = 0;  
  154.         switch (uriMatcher.match(uri)){  
  155.             case BOOKS:  
  156.                 count = booksDB.update(  
  157.                         DATABASE_TABLE,  
  158.                         values,  
  159.                         selection,  
  160.                         selectionArgs);  
  161.                 break;  
  162.             case BOOK_ID:                 
  163.                 count = booksDB.update(  
  164.                         DATABASE_TABLE,  
  165.                         values,  
  166.                         _ID + " = " + uri.getPathSegments().get(1) +  
  167.                         (!TextUtils.isEmpty(selection) ? " AND (" +  
  168.                             selection + ')' : ""),  
  169.                         selectionArgs);  
  170.                 break;  
  171.             defaultthrow new IllegalArgumentException("Unknown URI " + uri);     
  172.         }        
  173.         getContext().getContentResolver().notifyChange(uri, null);  
  174.         return count;  
  175.     }  
Step 6
 
Open and update the "AndroidManifest.xml" file from "res/AndroidManifest.xml" and update it as given below.
  1. <?xml version="1.0" encoding="utf-8"?>  
  2. <manifest xmlns:android="http://schemas.android.com/apk/res/android"  
  3.     package="com.content_provider"  
  4.     android:versionCode="1"  
  5.     android:versionName="1.0" >  
  6.     <uses-sdk  
  7.         android:minSdkVersion="8"  
  8.         android:targetSdkVersion="17" />  
  9.     <application  
  10.         android:allowBackup="true"  
  11.         android:icon="@drawable/ic_launcher"  
  12.         android:label="@string/app_name"  
  13.         android:theme="@style/AppTheme" >  
  14.         <activity  
  15.             android:name="com.content_provider.MainActivity"  
  16.             android:label="@string/app_name" >  
  17.             <intent-filter>  
  18.                 <action android:name="android.intent.action.MAIN" />  
  19.                 <category android:name="android.intent.category.LAUNCHER" />  
  20.             </intent-filter>  
  21.         </activity>  
  22.          <provider android:name="ContentDiary"  
  23.                 android:authorities="com.ContentDiary.provider.books" />  
  24.     </application>  
  25. </manifest> 
Step 7
 
See the output:
 
isbn.jpg
 
You can use the URI "content://com.contentDAiry.provider.books/books/5" in another application.
 
uri_contentProvider.jpg
 


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