ContentProvider 是 Andorid 中专门用于不同应用间进行数据共享的方式，底层实现也是 Binder 。
前面在 《第一行代码》读书笔记（五）– 应用组件之 ContentProvider 介绍过，这里就不再详细记录了。
首先继承 ContentProvider 类实现自己的 Provider ：
public class BookProvider extends ContentProvider {
private static final String TAG = "BookProvider";
public static final String AUTHORITY = "com.wshunli.ipc.demo.book.provider";
public static final Uri BOOK_CONTENT_URI = Uri.parse("content://"
+ AUTHORITY + "/book");
public static final Uri USER_CONTENT_URI = Uri.parse("content://"
+ AUTHORITY + "/user");
public static final int BOOK_URI_CODE = 0;
public static final int USER_URI_CODE = 1;
private static final UriMatcher sUriMatcher = new UriMatcher(
UriMatcher.NO_MATCH);
static {
sUriMatcher.addURI(AUTHORITY, "book", BOOK_URI_CODE);
sUriMatcher.addURI(AUTHORITY, "user", USER_URI_CODE);
}
private Context context;
private SQLiteDatabase db;
public BookProvider() {
}
@Override
public boolean onCreate() {
context = getContext();
initProviderData();
return true;
}
private void initProviderData() {
db = new DBHelper(context).getWritableDatabase();
db.execSQL("delete from " + DBHelper.BOOK_TABLE_NAME);
db.execSQL("delete from " + DBHelper.USER_TALBE_NAME);
db.execSQL("insert into book values(3,'Android');");
db.execSQL("insert into book values(4,'Ios');");
db.execSQL("insert into book values(5,'Html5');");
db.execSQL("insert into user values(1,'jake',1);");
db.execSQL("insert into user values(2,'jasmine',0);");
}
@Override
public String getType(Uri uri) {
Log.d(TAG, "getType: ");
return null;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
String table = getTableName(uri);
if (table == null) {
throw new IllegalArgumentException("Unsupported URI: " + uri);
}
db.insert(table, null, values);
context.getContentResolver().notifyChange(uri, null);
return uri;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
String table = getTableName(uri);
if (table == null) {
throw new IllegalArgumentException("Unsupported URI: " + uri);
}
return db.query(table, projection, selection, selectionArgs, null, null, sortOrder, null);
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
String table = getTableName(uri);
if (table == null) {
throw new IllegalArgumentException("Unsupported URI: " + uri);
}
int row = db.update(table, values, selection, selectionArgs);
if (row > 0) {
context.getContentResolver().notifyChange(uri, null);
}
return row;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
String table = getTableName(uri);
if (table == null) {
throw new IllegalArgumentException("Unsupported URI: " + uri);
}
int count = db.delete(table, selection, selectionArgs);
if (count > 0) {
context.getContentResolver().notifyChange(uri, null);
}
return count;
}
private String getTableName(Uri uri) {
String tableName = null;
switch (sUriMatcher.match(uri)) {
case BOOK_URI_CODE:
tableName = DBHelper.BOOK_TABLE_NAME;
break;
case USER_URI_CODE:
tableName = DBHelper.USER_TALBE_NAME;
break;
default:
break;
}
return tableName;
}
}记得在 AndroidManifest 中声明：
<provider
android:name=".content.BookProvider"
android:authorities="com.wshunli.ipc.demo.book.provider"
android:enabled="true"
android:exported="true"
android:permission="com.wshunli.ipc.demo.PROVIDER"
android:process=":remote" />其中 DBHelper 为数据库帮助类，代码如下：
public class DBHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "book_provider.db";
public static final String BOOK_TABLE_NAME = "book";
public static final String USER_TALBE_NAME = "user";
private static final int DB_VERSION = 3;
private String CREATE_BOOK_TABLE = "CREATE TABLE IF NOT EXISTS "
+ BOOK_TABLE_NAME + "(_id INTEGER PRIMARY KEY," + "name TEXT)";
private String CREATE_USER_TABLE = "CREATE TABLE IF NOT EXISTS "
+ USER_TALBE_NAME + "(_id INTEGER PRIMARY KEY," + "name TEXT,"
+ "sex INT)";
public DBHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_BOOK_TABLE);
db.execSQL(CREATE_USER_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}然后就是使用了，新建 Activity ：
public class ProviderActivity extends AppCompatActivity {
private static final String TAG = "ProviderActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_provider);
// Uri uri = Uri.parse("content://com.wshunli.ipc.demo.book.provider");
// getContentResolver().query(uri, null, null, null, null);
Uri bookUri = Uri.parse("content://com.wshunli.ipc.demo.book.provider/book");
ContentValues values = new ContentValues();
values.put("_id", 6);
values.put("name", "程序设计的艺术");
getContentResolver().insert(bookUri, values);
Cursor bookCursor = getContentResolver().query(bookUri, new String[]{"_id", "name"}, null, null, null);
while (bookCursor.moveToNext()) {
Book book = new Book();
book.bookId = bookCursor.getInt(0);
book.bookName = bookCursor.getString(1);
Log.d(TAG, "query book:" + book.toString());
}
bookCursor.close();
Uri userUri = Uri.parse("content://com.wshunli.ipc.demo.book.provider/user");
Cursor userCursor = getContentResolver().query(userUri, new String[]{"_id", "name", "sex"}, null, null, null);
while (userCursor.moveToNext()) {
User user = new User();
user.userId = userCursor.getInt(0);
user.userName = userCursor.getString(1);
user.isMale = userCursor.getInt(2) == 1;
Log.d(TAG, "query user:" + user.toString());
}
userCursor.close();
}
}日志结果如下：
参考资料
1、《Android开发艺术探索》 -- 2.4.5 使用 ContentProvider
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