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());
}
}
}