Les meilleures pratiques pour exposer plusieurs tables à l'aide des fournisseurs de contenus Android

C'est probablement un peu tard pour vous, mais d'autres peuvent trouver cela utile.

Vous devez d'abord créer plusieurs CONTENT_URIs

public static final Uri CONTENT_URI1 = 
    Uri.parse("content://"+ PROVIDER_NAME + "/sampleuri1");
public static final Uri CONTENT_URI2 = 
    Uri.parse("content://"+ PROVIDER_NAME + "/sampleuri2");

Vous développez votre URI Matcher

private static final UriMatcher uriMatcher;
static {
    uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
    uriMatcher.addURI(PROVIDER_NAME, "sampleuri1", SAMPLE1);
    uriMatcher.addURI(PROVIDER_NAME, "sampleuri1/#", SAMPLE1_ID);      
    uriMatcher.addURI(PROVIDER_NAME, "sampleuri2", SAMPLE2);
    uriMatcher.addURI(PROVIDER_NAME, "sampleuri2/#", SAMPLE2_ID);      
}

Ensuite créer vos tables

private static final String DATABASE_NAME = "sample.db";
private static final String DATABASE_TABLE1 = "sample1";
private static final String DATABASE_TABLE2 = "sample2";
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_CREATE1 =
    "CREATE TABLE IF NOT EXISTS " + DATABASE_TABLE1 + 
    " (" + _ID1 + " INTEGER PRIMARY KEY AUTOINCREMENT," + 
    "data text, stuff text);";
private static final String DATABASE_CREATE2 =
    "CREATE TABLE IF NOT EXISTS " + DATABASE_TABLE2 + 
    " (" + _ID2 + " INTEGER PRIMARY KEY AUTOINCREMENT," + 
    "data text, stuff text);";

N'oubliez pas d'ajouter le deuxième DATABASE_CREATE à onCreate()

Vous allez utiliser un cas de commutateur bloc de déterminer ce tableau est utilisé. C'est mon insérer le code

@Override
public Uri insert(Uri uri, ContentValues values) {
    Uri _uri = null;
    switch (uriMatcher.match(uri)){
    case SAMPLE1:
        long _ID1 = db.insert(DATABASE_TABLE1, "", values);
        //---if added successfully---
        if (_ID1 > 0) {
            _uri = ContentUris.withAppendedId(CONTENT_URI1, _ID1);
            getContext().getContentResolver().notifyChange(_uri, null);    
        }
        break;
    case SAMPLE2:
        long _ID2 = db.insert(DATABASE_TABLE2, "", values);
        //---if added successfully---
        if (_ID2 > 0) {
            _uri = ContentUris.withAppendedId(CONTENT_URI2, _ID2);
            getContext().getContentResolver().notifyChange(_uri, null);    
        }
        break;
    default: throw new SQLException("Failed to insert row into " + uri);
    }
    return _uri;                
}

Vous aurez besoin de diviser le delete, update, getType, etc. Partout où votre fournisseur d'appels pour DATABASE_TABLE ou CONTENT_URI, vous allez ajouter un cas et ont DATABASE_TABLE1 ou CONTENT_URI1 dans l'un et n ° 2 dans la prochaine et ainsi de suite pour autant que vous le souhaitez.

Un ContentProvider peut servir à de multiples tables, mais ils devraient être quelque peu liés. Il fera une différence si vous avez l'intention de synchroniser vos fournisseurs. Si vous voulez séparer les synchronisations pour, disons, les Contacts, la Messagerie ou le Calendrier, vous aurez besoin de différents fournisseurs pour chacun d'eux, même s'ils finissent par être dans la même base de données ou sont synchronisés avec le même service, en raison de la Synchronisation des Adaptateurs sont directement liés à un fournisseur particulier.

Aussi loin que je peux dire, vous ne pouvez utiliser qu'un seul SQLiteOpenHelper par base de données, car il stocke ses des méta-informations dans une table dans la base de données. Donc, si votre ContentProviders accéder à la même base de données, vous aurez à part l'aide somewhow.

J'ai trouvé la meilleure démonstration et explication pour ContentProvider et je pense qu'il a suivie Android Normes.

Contrat Classes

 /**
   * The Content Authority is a name for the entire content provider, similar to the relationship
   * between a domain name and its website. A convenient string to use for content authority is
   * the package name for the app, since it is guaranteed to be unique on the device.
   */
  public static final String CONTENT_AUTHORITY = "com.androidessence.moviedatabase";

  /**
   * The content authority is used to create the base of all URIs which apps will use to
   * contact this content provider.
   */
  private static final Uri BASE_CONTENT_URI = Uri.parse("content://" + CONTENT_AUTHORITY);

  /**
   * A list of possible paths that will be appended to the base URI for each of the different
   * tables.
   */
  public static final String PATH_MOVIE = "movie";
  public static final String PATH_GENRE = "genre";

et les Classes internes:

 /**
   * Create one class for each table that handles all information regarding the table schema and
   * the URIs related to it.
   */
  public static final class MovieEntry implements BaseColumns {
      // Content URI represents the base location for the table
      public static final Uri CONTENT_URI =
              BASE_CONTENT_URI.buildUpon().appendPath(PATH_MOVIE).build();

      // These are special type prefixes that specify if a URI returns a list or a specific item
      public static final String CONTENT_TYPE =
              "vnd.android.cursor.dir/" + CONTENT_URI  + "/" + PATH_MOVIE;
      public static final String CONTENT_ITEM_TYPE =
              "vnd.android.cursor.item/" + CONTENT_URI + "/" + PATH_MOVIE;

      // Define the table schema
      public static final String TABLE_NAME = "movieTable";
      public static final String COLUMN_NAME = "movieName";
      public static final String COLUMN_RELEASE_DATE = "movieReleaseDate";
      public static final String COLUMN_GENRE = "movieGenre";

      // Define a function to build a URI to find a specific movie by it's identifier
      public static Uri buildMovieUri(long id){
          return ContentUris.withAppendedId(CONTENT_URI, id);
      }
  }

  public static final class GenreEntry implements BaseColumns{
      public static final Uri CONTENT_URI =
              BASE_CONTENT_URI.buildUpon().appendPath(PATH_GENRE).build();

      public static final String CONTENT_TYPE =
              "vnd.android.cursor.dir/" + CONTENT_URI + "/" + PATH_GENRE;
      public static final String CONTENT_ITEM_TYPE =
              "vnd.android.cursor.item/" + CONTENT_URI + "/" + PATH_GENRE;

      public static final String TABLE_NAME = "genreTable";
      public static final String COLUMN_NAME = "genreName";

      public static Uri buildGenreUri(long id){
          return ContentUris.withAppendedId(CONTENT_URI, id);
      }
  }

Maintenant la création de la Base de données à l'aide de SQLiteOpenHelper:

public class MovieDBHelper extends SQLiteOpenHelper{
/**
* Defines the database version. This variable must be incremented in order for onUpdate to
* be called when necessary.
*/
private static final int DATABASE_VERSION = 1;
/**
* The name of the database on the device.
*/
private static final String DATABASE_NAME = "movieList.db";
/**
* Default constructor.
* @param context The application context using this database.
*/
public MovieDBHelper(Context context){
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
/**
* Called when the database is first created.
* @param db The database being created, which all SQL statements will be executed on.
*/
@Override
public void onCreate(SQLiteDatabase db) {
addGenreTable(db);
addMovieTable(db);
}
/**
* Called whenever DATABASE_VERSION is incremented. This is used whenever schema changes need
* to be made or new tables are added.
* @param db The database being updated.
* @param oldVersion The previous version of the database. Used to determine whether or not
*                   certain updates should be run.
* @param newVersion The new version of the database.
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
/**
* Inserts the genre table into the database.
* @param db The SQLiteDatabase the table is being inserted into.
*/
private void addGenreTable(SQLiteDatabase db){
db.execSQL(
"CREATE TABLE " + MovieContract.GenreEntry.TABLE_NAME + " (" +
MovieContract.GenreEntry._ID + " INTEGER PRIMARY KEY, " +
MovieContract.GenreEntry.COLUMN_NAME + " TEXT UNIQUE NOT NULL);"
);
}
/**
* Inserts the movie table into the database.
* @param db The SQLiteDatabase the table is being inserted into.
*/
private void addMovieTable(SQLiteDatabase db){
db.execSQL(
"CREATE TABLE " + MovieContract.MovieEntry.TABLE_NAME + " (" +
MovieContract.MovieEntry._ID + " INTEGER PRIMARY KEY, " +
MovieContract.MovieEntry.COLUMN_NAME + " TEXT NOT NULL, " +
MovieContract.MovieEntry.COLUMN_RELEASE_DATE + " TEXT NOT NULL, " +
MovieContract.MovieEntry.COLUMN_GENRE + " INTEGER NOT NULL, " +
"FOREIGN KEY (" + MovieContract.MovieEntry.COLUMN_GENRE + ") " +
"REFERENCES " + MovieContract.GenreEntry.TABLE_NAME + " (" + MovieContract.GenreEntry._ID + "));"
);
}
}

Fournisseur De Contenu:

public class MovieProvider extends ContentProvider {
// Use an int for each URI we will run, this represents the different queries
private static final int GENRE = 100;
private static final int GENRE_ID = 101;
private static final int MOVIE = 200;
private static final int MOVIE_ID = 201;
private static final UriMatcher sUriMatcher = buildUriMatcher();
private MovieDBHelper mOpenHelper;
@Override
public boolean onCreate() {
mOpenHelper = new MovieDBHelper(getContext());
return true;
}
/**
* Builds a UriMatcher that is used to determine witch database request is being made.
*/
public static UriMatcher buildUriMatcher(){
String content = MovieContract.CONTENT_AUTHORITY;
// All paths to the UriMatcher have a corresponding code to return
// when a match is found (the ints above).
UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
matcher.addURI(content, MovieContract.PATH_GENRE, GENRE);
matcher.addURI(content, MovieContract.PATH_GENRE + "/#", GENRE_ID);
matcher.addURI(content, MovieContract.PATH_MOVIE, MOVIE);
matcher.addURI(content, MovieContract.PATH_MOVIE + "/#", MOVIE_ID);
return matcher;
}
@Override
public String getType(Uri uri) {
switch(sUriMatcher.match(uri)){
case GENRE:
return MovieContract.GenreEntry.CONTENT_TYPE;
case GENRE_ID:
return MovieContract.GenreEntry.CONTENT_ITEM_TYPE;
case MOVIE:
return MovieContract.MovieEntry.CONTENT_TYPE;
case MOVIE_ID:
return MovieContract.MovieEntry.CONTENT_ITEM_TYPE;
default:
throw new UnsupportedOperationException("Unknown uri: " + uri);
}
}
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
final SQLiteDatabase db = mOpenHelper.getWritableDatabase();
Cursor retCursor;
switch(sUriMatcher.match(uri)){
case GENRE:
retCursor = db.query(
MovieContract.GenreEntry.TABLE_NAME,
projection,
selection,
selectionArgs,
null,
null,
sortOrder
);
break;
case GENRE_ID:
long _id = ContentUris.parseId(uri);
retCursor = db.query(
MovieContract.GenreEntry.TABLE_NAME,
projection,
MovieContract.GenreEntry._ID + " = ?",
new String[]{String.valueOf(_id)},
null,
null,
sortOrder
);
break;
case MOVIE:
retCursor = db.query(
MovieContract.MovieEntry.TABLE_NAME,
projection,
selection,
selectionArgs,
null,
null,
sortOrder
);
break;
case MOVIE_ID:
_id = ContentUris.parseId(uri);
retCursor = db.query(
MovieContract.MovieEntry.TABLE_NAME,
projection,
MovieContract.MovieEntry._ID + " = ?",
new String[]{String.valueOf(_id)},
null,
null,
sortOrder
);
break;
default:
throw new UnsupportedOperationException("Unknown uri: " + uri);
}
// Set the notification URI for the cursor to the one passed into the function. This
// causes the cursor to register a content observer to watch for changes that happen to
// this URI and any of it's descendants. By descendants, we mean any URI that begins
// with this path.
retCursor.setNotificationUri(getContext().getContentResolver(), uri);
return retCursor;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
final SQLiteDatabase db = mOpenHelper.getWritableDatabase();
long _id;
Uri returnUri;
switch(sUriMatcher.match(uri)){
case GENRE:
_id = db.insert(MovieContract.GenreEntry.TABLE_NAME, null, values);
if(_id > 0){
returnUri =  MovieContract.GenreEntry.buildGenreUri(_id);
} else{
throw new UnsupportedOperationException("Unable to insert rows into: " + uri);
}
break;
case MOVIE:
_id = db.insert(MovieContract.MovieEntry.TABLE_NAME, null, values);
if(_id > 0){
returnUri = MovieContract.MovieEntry.buildMovieUri(_id);
} else{
throw new UnsupportedOperationException("Unable to insert rows into: " + uri);
}
break;
default:
throw new UnsupportedOperationException("Unknown uri: " + uri);
}
// Use this on the URI passed into the function to notify any observers that the uri has
// changed.
getContext().getContentResolver().notifyChange(uri, null);
return returnUri;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
final SQLiteDatabase db = mOpenHelper.getWritableDatabase();
int rows; // Number of rows effected
switch(sUriMatcher.match(uri)){
case GENRE:
rows = db.delete(MovieContract.GenreEntry.TABLE_NAME, selection, selectionArgs);
break;
case MOVIE:
rows = db.delete(MovieContract.MovieEntry.TABLE_NAME, selection, selectionArgs);
break;
default:
throw new UnsupportedOperationException("Unknown uri: " + uri);
}
// Because null could delete all rows:
if(selection == null || rows != 0){
getContext().getContentResolver().notifyChange(uri, null);
}
return rows;
}
@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
final SQLiteDatabase db = mOpenHelper.getWritableDatabase();
int rows;
switch(sUriMatcher.match(uri)){
case GENRE:
rows = db.update(MovieContract.GenreEntry.TABLE_NAME, values, selection, selectionArgs);
break;
case MOVIE:
rows = db.update(MovieContract.MovieEntry.TABLE_NAME, values, selection, selectionArgs);
break;
default:
throw new UnsupportedOperationException("Unknown uri: " + uri);
}
if(rows != 0){
getContext().getContentResolver().notifyChange(uri, null);
}
return rows;
}
}

J'espère que ça vous aide.

Démo sur GitHub: https://github.com/androidessence/MovieDatabase

Article Complet : https://guides.codepath.com/android/creating-content-providers

Références:

• http://code.tutsplus.com/tutorials/android-sdk_content-providers--mobile-5549

• http://www.grokkingandroid.com/android-tutorial-writing-your-own-content-provider/

• http://developer.android.com/guide/topics/providers/content-providers.html

• https://thenewcircle.com/s/post/1375/android_content_provider_tutorial

• http://www.grokkingandroid.com/android-tutorial-content-provider-basics/

• http://androidessence.com/

Note : j'ai copié le code tout simplement parce que si le lien de démo ou de l'article peut être supprimer à l'avenir.