[大数据]ContentProvider的简单使用

ContentProvider 提供app间跨进程数据的共享，只是一种机制，本身并不提供数据存储服务，需配合数据库或别的持久化存储使用。

public class MyProvider extends ContentProvider {

    private static final String AUTHORITY = "com.example.test.provider"; //用于区分不同的ContentProvider

    private static final UriMatcher sUriMatcher;
    private static final int CODE1 = 0;

    private static final int CODE2 = 1;

    private static final String F1 = "f1";

    private static final String F2 = "f2";

    static {
        sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        //只对这两种uri进行处理 如果匹配上 通过 sUriMatcher.match(uri)可以得到 对应的Code
        sUriMatcher.addURI(AUTHORITY, F1, CODE1);
        sUriMatcher.addURI(AUTHORITY, F2, CODE2);
    }

    @Override
    public boolean onCreate() {
        return true;
    }

    @Nullable
    @Override
    public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection,
            @Nullable String[] selectionArgs, @Nullable String sortOrder) {
        String[] tableCursor = new String[] { "name", "job", "salary" };
        MatrixCursor cursor = new MatrixCursor(tableCursor);
        switch (sUriMatcher.match(uri)) {
            case CODE1:
                cursor.addRow(new Object[] { "1111", "111", "11" });
                break;
            case CODE2:
                cursor.addRow(new Object[] { "2222", "222", "22" });
                break;
        }
        return cursor;
    }

    @Nullable
    @Override
    public String getType(@NonNull Uri uri) {
        return null;
    }

    @Nullable
    @Override
    public Uri insert(@NonNull Uri uri, @Nullable ContentValues values) {
        return null;
    }

    @Override
    public int delete(@NonNull Uri uri, @Nullable String selection,
            @Nullable String[] selectionArgs) {
        return 0;
    }

    @Override
    public int update(@NonNull Uri uri, @Nullable ContentValues values, @Nullable String selection,
            @Nullable String[] selectionArgs) {
        return 0;
    }
}

public class MyService extends Service {
    private static final String AUTHORITY = "com.example.test.provider";
    public static Uri sUri = Uri.parse("content://" + AUTHORITY + "/f2");

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
    
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
查找
        Cursor query = getContentResolver().query(sUri, null, null, null, null, null);
        if (query!=null){
            query.moveToNext();
            String s0 = query.getString(0);
            String s1 = query.getString(1);
            Log.e("test","s0"+s0+"    s1"+s1);
        }
        return super.onStartCommand(intent, flags, startId);
    }
}

 <service android:name=".MyService" />

        <provider
            android:authorities="com.example.test.provider"
            android:name=".MyProvider"
            android:exported="true"
            android:enabled="true"/>