android.database.DatabaseUtils#STATEMENT_BEGIN源码实例Demo

/**
 * Performs special reinterpretation of certain SQL statements such as "BEGIN",
 * "COMMIT" and "ROLLBACK" to ensure that transaction state invariants are
 * maintained.
 *
 * This function is mainly used to support legacy apps that perform their
 * own transactions by executing raw SQL rather than calling {@link #beginTransaction}
 * and the like.
 *
 * @param sql The SQL statement to execute.
 * @param bindArgs The arguments to bind, or null if none.
 * @param connectionFlags The connection flags to use if a connection must be
 * acquired by this operation.  Refer to {@link SQLiteConnectionPool}.
 * @param cancellationSignal A signal to cancel the operation in progress, or null if none.
 * @return True if the statement was of a special form that was handled here,
 * false otherwise.
 *
 * @throws SQLiteException if an error occurs, such as a syntax error
 * or invalid number of bind arguments.
 * @throws OperationCanceledException if the operation was canceled.
 */
private boolean executeSpecial(String sql, Object[] bindArgs, int connectionFlags,
        CancellationSignal cancellationSignal) {
    if (cancellationSignal != null) {
        cancellationSignal.throwIfCanceled();
    }

    final int type = DatabaseUtils.getSqlStatementType(sql);
    switch (type) {
        case DatabaseUtils.STATEMENT_BEGIN:
            beginTransaction(TRANSACTION_MODE_EXCLUSIVE, null, connectionFlags,
                    cancellationSignal);
            return true;

        case DatabaseUtils.STATEMENT_COMMIT:
            setTransactionSuccessful();
            endTransaction(cancellationSignal);
            return true;

        case DatabaseUtils.STATEMENT_ABORT:
            endTransaction(cancellationSignal);
            return true;
    }
    return false;
}
 

/**
 * Performs special reinterpretation of certain SQL statements such as "BEGIN",
 * "COMMIT" and "ROLLBACK" to ensure that transaction state invariants are
 * maintained.
 *
 * This function is mainly used to support legacy apps that perform their
 * own transactions by executing raw SQL rather than calling {@link #beginTransaction}
 * and the like.
 *
 * @param sql The SQL statement to execute.
 * @param bindArgs The arguments to bind, or null if none.
 * @param connectionFlags The connection flags to use if a connection must be
 * acquired by this operation.  Refer to {@link SQLiteConnectionPool}.
 * @param cancellationSignal A signal to cancel the operation in progress, or null if none.
 * @return True if the statement was of a special form that was handled here,
 * false otherwise.
 *
 * @throws SQLiteException if an error occurs, such as a syntax error
 * or invalid number of bind arguments.
 * @throws OperationCanceledException if the operation was canceled.
 */
private boolean executeSpecial(String sql, Object[] bindArgs, int connectionFlags,
        CancellationSignal cancellationSignal) {
    if (cancellationSignal != null) {
        cancellationSignal.throwIfCanceled();
    }

    final int type = DatabaseUtils.getSqlStatementType(sql);
    switch (type) {
        case DatabaseUtils.STATEMENT_BEGIN:
            beginTransaction(TRANSACTION_MODE_EXCLUSIVE, null, connectionFlags,
                    cancellationSignal);
            return true;

        case DatabaseUtils.STATEMENT_COMMIT:
            setTransactionSuccessful();
            endTransaction(cancellationSignal);
            return true;

        case DatabaseUtils.STATEMENT_ABORT:
            endTransaction(cancellationSignal);
            return true;
    }
    return false;
}
 

SQLiteProgram(SQLiteDatabase db, String sql, Object[] bindArgs,
        CancellationSignal cancellationSignalForPrepare) {
    mDatabase = db;
    mSql = sql.trim();

    int n = DatabaseUtils.getSqlStatementType(mSql);
    switch (n) {
        case DatabaseUtils.STATEMENT_BEGIN:
        case DatabaseUtils.STATEMENT_COMMIT:
        case DatabaseUtils.STATEMENT_ABORT:
            mReadOnly = false;
            mColumnNames = EMPTY_STRING_ARRAY;
            mNumParameters = 0;
            break;

        default:
            boolean assumeReadOnly = (n == DatabaseUtils.STATEMENT_SELECT);
            SQLiteStatementInfo info = new SQLiteStatementInfo();
            db.getThreadSession().prepare(mSql,
                    db.getThreadDefaultConnectionFlags(assumeReadOnly),
                    cancellationSignalForPrepare, info);
            mReadOnly = info.readOnly;
            mColumnNames = info.columnNames;
            mNumParameters = info.numParameters;
            break;
    }

    if (bindArgs != null && bindArgs.length > mNumParameters) {
        throw new IllegalArgumentException("Too many bind arguments.  "
                + bindArgs.length + " arguments were provided but the statement needs "
                + mNumParameters + " arguments.");
    }

    if (mNumParameters != 0) {
        mBindArgs = new Object[mNumParameters];
        if (bindArgs != null) {
            System.arraycopy(bindArgs, 0, mBindArgs, 0, bindArgs.length);
        }
    } else {
        mBindArgs = null;
    }
}
 

SQLiteProgram(SQLiteDatabase db, String sql, Object[] bindArgs,
        CancellationSignal cancellationSignalForPrepare) {
    mDatabase = db;
    mSql = sql.trim();

    int n = DatabaseUtils.getSqlStatementType(mSql);
    switch (n) {
        case DatabaseUtils.STATEMENT_BEGIN:
        case DatabaseUtils.STATEMENT_COMMIT:
        case DatabaseUtils.STATEMENT_ABORT:
            mReadOnly = false;
            mColumnNames = EMPTY_STRING_ARRAY;
            mNumParameters = 0;
            break;

        default:
            boolean assumeReadOnly = (n == DatabaseUtils.STATEMENT_SELECT);
            SQLiteStatementInfo info = new SQLiteStatementInfo();
            db.getThreadSession().prepare(mSql,
                    db.getThreadDefaultConnectionFlags(assumeReadOnly),
                    cancellationSignalForPrepare, info);
            mReadOnly = info.readOnly;
            mColumnNames = info.columnNames;
            mNumParameters = info.numParameters;
            break;
    }

    if (bindArgs != null && bindArgs.length > mNumParameters) {
        throw new IllegalArgumentException("Too many bind arguments.  "
                + bindArgs.length + " arguments were provided but the statement needs "
                + mNumParameters + " arguments.");
    }

    if (mNumParameters != 0) {
        mBindArgs = new Object[mNumParameters];
        if (bindArgs != null) {
            System.arraycopy(bindArgs, 0, mBindArgs, 0, bindArgs.length);
        }
    } else {
        mBindArgs = null;
    }
}