Create Your Own Content Providers

Description

The following code shows how to Create Your Own Content Providers.

All you need to do is extend the abstract ContentProvider class and override the various methods defined within it.

Example


package com.java2s.myapplication3.app;
//from   ww w  .  jav  a2  s.com
import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
public class BooksProvider extends ContentProvider {
    static final String PROVIDER_NAME =
            "com.java2s.provider.Books";

    static final Uri CONTENT_URI =
            Uri.parse ("content://"+ PROVIDER_NAME + "/books");

    static final String _ID = "_id";
    static final String TITLE = "title";
    static final String ISBN = "isbn";

    static final int BOOKS = 1;
    static final int BOOK_ID = 2;

    private static final UriMatcher uriMatcher;
    static{
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(PROVIDER_NAME, "books", BOOKS);
        uriMatcher.addURI(PROVIDER_NAME, "books/#", BOOK_ID);
    }

    SQLiteDatabase booksDB;
    static final String DATABASE_NAME = "Books";
    static final String DATABASE_TABLE = "titles";
    static final int DATABASE_VERSION = 1;
    static final String DATABASE_CREATE =
            "create table " + DATABASE_TABLE +
                    " (_id integer primary key autoincrement, "
                    + "title text not null, isbn text not null);";

    private static class DatabaseHelper extends SQLiteOpenHelper
    {
        DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db)
        {
            db.execSQL(DATABASE_CREATE);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion,
                              int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS titles");
            onCreate(db);
        }
    }

    @Override
    public int delete(Uri arg0, String arg1, String[] arg2) {
        // arg0 = uri
        // arg1 = selection
        // arg2 = selectionArgs
        int count=0;
        switch (uriMatcher.match(arg0)){
            case BOOKS:
                count = booksDB.delete(
                        DATABASE_TABLE,
                        arg1,
                        arg2);
                break;
            case BOOK_ID:
                String id = arg0.getPathSegments().get(1);
                count = booksDB.delete(DATABASE_TABLE,_ID + " = 4" ,arg2);
                break;
            default: throw new IllegalArgumentException("Unknown URI " + arg0);
        }
        getContext().getContentResolver().notifyChange(arg0, null);
        return count;
    }

    @Override
    public String getType(Uri uri) {
        switch (uriMatcher.match(uri)){
            //get all books
            case BOOKS:
                return "vnd.android.cursor.dir/vnd.java2s.books ";

            //get a particular book
            case BOOK_ID:
                return "vnd.android.cursor.item/vnd.java2s.books ";

            default:
                throw new IllegalArgumentException("Unsupported URI: " + uri);
        }
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        //add a new book
        long rowID = booksDB.insert(
                DATABASE_TABLE,
                "",
                values);
        //if added successfully
        if (rowID>0)
        {
            Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
            getContext().getContentResolver().notifyChange(_uri, null);
            return _uri;
        }
        throw new SQLException("Failed to insert row into " + uri);
    }

    @Override
    public boolean onCreate() {
        Context context = getContext();
        DatabaseHelper dbHelper = new DatabaseHelper(context);
        booksDB = dbHelper.getWritableDatabase();
        return (booksDB == null)? false:true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
                        String[] selectionArgs, String sortOrder) {
        SQLiteQueryBuilder sqlBuilder = new SQLiteQueryBuilder();
        sqlBuilder.setTables(DATABASE_TABLE);

        if (uriMatcher.match(uri) == BOOK_ID)
            //if getting a particular book
            sqlBuilder.appendWhere(
                    _ID + " = " + uri.getPathSegments().get(1));

        if (sortOrder==null || sortOrder=="")
            sortOrder = TITLE;

        Cursor c = sqlBuilder.query(
                booksDB,
                projection,
                selection,
                selectionArgs,
                null,
                null,
                sortOrder);

        //register to watch a content URI for changes
        c.setNotificationUri(getContext().getContentResolver(), uri);
        return c;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection,
                      String[] selectionArgs) {
        int count = 0;
        switch (uriMatcher.match(uri)){
            case BOOKS:
                count = booksDB.update(
                        DATABASE_TABLE,
                        values,
                        selection,
                        selectionArgs);
                break;
            case BOOK_ID:
                count = booksDB.update(
                        DATABASE_TABLE,
                        values,
                        _ID + " = 2" ,selectionArgs);
                break;
            default: throw new IllegalArgumentException("Unknown URI " + uri);
        }
        getContext().getContentResolver().notifyChange(uri, null);
        return count;
    }
}

Add the following statements to the AndroidManifest.xml file:


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.java2s.ContentProviders"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="14" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".ContentProvidersActivity" >
              <intent-filter >
                  <action android:name="android.intent.action.MAIN" />

                  <category android:name="android.intent.category.LAUNCHER" />
              </intent-filter>
          </activity>
          <provider android:name="BooksProvider"
              android:authorities="com.java2s.provider.Books">
          </provider>
      </application>

</manifest>


Use The Content Provider


<?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="ISBN" />

<EditText
    android:id="@+id/txtISBN"
    android:layout_height="wrap_content"
    android:layout_width="fill_parent" />

<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Title" />

<EditText
    android:id="@+id/txtTitle"
    android:layout_height="wrap_content"
    android:layout_width="fill_parent" />

<Button
    android:text="Add title"
    android:id="@+id/btnAdd"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:onClick="onClickAddTitle" />

<Button
    android:text="Retrieve titles"
    android:id="@+id/btnRetrieve"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:onClick="onClickRetrieveTitles"  />

</LinearLayout>

Java code


package com.java2s.myapplication3.app;
/*from ww w.  java  2s. com*/
import android.app.Activity;
import android.content.ContentValues;
import android.content.CursorLoader;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    public void onClickAddTitle(View view) {
        //add a book
        ContentValues values = new ContentValues();
        values.put(BooksProvider.TITLE, ((EditText)
                findViewById(R.id.txtTitle)).getText().toString());
        values.put(BooksProvider.ISBN, ((EditText)
                findViewById(R.id.txtISBN)).getText().toString());
        Uri uri = getContentResolver().insert(
                BooksProvider.CONTENT_URI, values);
        Toast.makeText (getBaseContext(),uri.toString(),
                Toast.LENGTH_LONG).show();
    }

    public void onClickRetrieveTitles(View view) {
        //retrieve the titles
        Uri allTitles = Uri.parse (
                "content://com.java2s.provider.Books/books");
        Cursor c;
        if (android.os.Build.VERSION.SDK_INT <11) {
            //before Honeycomb
            c = managedQuery(allTitles, null, null, null,
                    "title desc");
        } else {
            //Honeycomb and later
            CursorLoader cursorLoader = new CursorLoader(
                    this,
                    allTitles, null, null, null,
                    "title desc");
            c = cursorLoader.loadInBackground();
        }
        if (c.moveToFirst()) {
            do{
                Toast.makeText (this,
                        c.getString(c.getColumnIndex(
                                BooksProvider._ID)) + ", " +
                                c.getString(c.getColumnIndex(
                                        BooksProvider.TITLE)) + ", " +
                                c.getString(c.getColumnIndex(
                                        BooksProvider.ISBN)),
                        Toast.LENGTH_SHORT).show();
            } while (c.moveToNext());
        }
    }

}




















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