netcursor.java

derby database source code.good for you.

        // so there is no need to drive a flowFetch (continue query) request for singleton select.
        if (position_ == lastValidBytePosition_) {
            // Check for ENDQRYRM, throw SqlException if already received one.
            checkAndThrowReceivedEndqryrm();

            // Send CNTQRY to complete the row/rowset.
            int lastValidByteBeforeFetch = completeSplitRow();

            // if lastValidBytePosition_ has not changed, and an ENDQRYRM was received,
            // throw a SqlException for the ENDQRYRM.
            checkAndThrowReceivedEndqryrm(lastValidByteBeforeFetch);
        }
        return dataBuffer_[position_++] & 0xff;
    }

    // Reads 1-byte from the dataBuffer from the current position.
    // If position is already at the end of the buffer, send CNTQRY to get more data.
    private int readFdocaOneByte(int index) throws org.apache.derby.client.am.DisconnectException, SqlException {
        // For singleton select, the complete row always comes back, even if multiple query blocks are required,
        // so there is no need to drive a flowFetch (continue query) request for singleton select.
        if (position_ == lastValidBytePosition_) {
            // Check for ENDQRYRM, throw SqlException if already received one.
            checkAndThrowReceivedEndqryrm();

            // Send CNTQRY to complete the row/rowset.
            int lastValidByteBeforeFetch = completeSplitRow(index);

            // if lastValidBytePosition_ has not changed, and an ENDQRYRM was received,
            // throw a SqlException for the ENDQRYRM.
            checkAndThrowReceivedEndqryrm(lastValidByteBeforeFetch);
        }
        return dataBuffer_[position_++] & 0xff;
    }

    // Reads <i>length</i> number of bytes from the dataBuffer starting from the
    // current position.  Returns a new byte array which contains the bytes read.
    // If current position plus length goes past the lastValidBytePosition, send
    // CNTQRY to get more data.
    private byte[] readFdocaBytes(int length) throws org.apache.derby.client.am.DisconnectException, SqlException {
        byte[] b = new byte[length];
        ;

        // For singleton select, the complete row always comes back, even if multiple query blocks are required,
        // so there is no need to drive a flowFetch (continue query) request for singleton select.
        if ((position_ + length) > lastValidBytePosition_) {
            // Check for ENDQRYRM, throw SqlException if already received one.
            checkAndThrowReceivedEndqryrm();

            // Send CNTQRY to complete the row/rowset.
            int lastValidByteBeforeFetch = completeSplitRow();

            // if lastValidBytePosition_ has not changed, and an ENDQRYRM was received,
            // throw a SqlException for the ENDQRYRM.
            checkAndThrowReceivedEndqryrm(lastValidByteBeforeFetch);
        }

        for (int i = 0; i < length; i++) {
            b[i] = dataBuffer_[position_++];
        }

        return b;
    }

    // Reads 2-bytes from the dataBuffer starting from the current position, and
    // returns an integer constructed from the 2-bytes.  If current position plus
    // 2 bytes goes past the lastValidBytePosition, send CNTQRY to get more data.
    private int readFdocaTwoByteLength() throws org.apache.derby.client.am.DisconnectException, SqlException {
        // For singleton select, the complete row always comes back, even if multiple query blocks are required,
        // so there is no need to drive a flowFetch (continue query) request for singleton select.
        if ((position_ + 2) > lastValidBytePosition_) {
            // Check for ENDQRYRM, throw SqlException if already received one.
            checkAndThrowReceivedEndqryrm();

            // Send CNTQRY to complete the row/rowset.
            int lastValidByteBeforeFetch = completeSplitRow();

            // if lastValidBytePosition_ has not changed, and an ENDQRYRM was received,
            // throw a SqlException for the ENDQRYRM.
            checkAndThrowReceivedEndqryrm(lastValidByteBeforeFetch);
        }

        return
                ((dataBuffer_[position_++] & 0xff) << 8) +
                ((dataBuffer_[position_++] & 0xff) << 0);
    }

    private int readFdocaTwoByteLength(int index) throws org.apache.derby.client.am.DisconnectException, SqlException {
        // For singleton select, the complete row always comes back, even if multiple query blocks are required,
        // so there is no need to drive a flowFetch (continue query) request for singleton select.
        if ((position_ + 2) > lastValidBytePosition_) {
            // Check for ENDQRYRM, throw SqlException if already received one.
            checkAndThrowReceivedEndqryrm();

            // Send CNTQRY to complete the row/rowset.
            int lastValidByteBeforeFetch = completeSplitRow(index);

            // if lastValidBytePosition_ has not changed, and an ENDQRYRM was received,
            // throw a SqlException for the ENDQRYRM.
            checkAndThrowReceivedEndqryrm(lastValidByteBeforeFetch);
        }

        return
                ((dataBuffer_[position_++] & 0xff) << 8) +
                ((dataBuffer_[position_++] & 0xff) << 0);
    }

    // Check if position plus length goes past the lastValidBytePosition.
    // If so, send CNTQRY to get more data.
    // length - number of bytes to skip
    // returns the number of bytes skipped
    private int skipFdocaBytes(int length) throws org.apache.derby.client.am.DisconnectException, SqlException {
        // For singleton select, the complete row always comes back, even if multiple query blocks are required,
        // so there is no need to drive a flowFetch (continue query) request for singleton select.
        if ((position_ + length) > lastValidBytePosition_) {
            // Check for ENDQRYRM, throw SqlException if already received one.
            checkAndThrowReceivedEndqryrm();

            // Send CNTQRY to complete the row/rowset.
            int lastValidByteBeforeFetch = completeSplitRow();

            // if lastValidBytePosition_ has not changed, and an ENDQRYRM was received,
            // throw a SqlException for the ENDQRYRM.
            checkAndThrowReceivedEndqryrm(lastValidByteBeforeFetch);
        }
        position_ += length;
        return length;
    }

    private int skipFdocaBytes(int length, int index) throws org.apache.derby.client.am.DisconnectException, SqlException {
        // For singleton select, the complete row always comes back, even if multiple query blocks are required,
        // so there is no need to drive a flowFetch (continue query) request for singleton select.
        if ((position_ + length) > lastValidBytePosition_) {
            // Check for ENDQRYRM, throw SqlException if already received one.
            checkAndThrowReceivedEndqryrm();

            // Send CNTQRY to complete the row/rowset.
            int lastValidByteBeforeFetch = completeSplitRow(index);

            // if lastValidBytePosition_ has not changed, and an ENDQRYRM was received,
            // throw a SqlException for the ENDQRYRM.
            checkAndThrowReceivedEndqryrm(lastValidByteBeforeFetch);
        }

        position_ += length;
        return length;
    }

    // Shift partial row bytes to beginning of dataBuffer,
    // and resets current row position, and lastValidBytePosition.
    // When we shift partial row, we'll have to recalculate column offsets
    // up to this column.
    private void shiftPartialRowToBeginning() {
        // Get the length to shift from the beginning of the partial row.
        int length = lastValidBytePosition_ - currentRowPosition_;

        // shift the data in the dataBufferStream
        dataBufferStream_.reset();
        if (dataBuffer_ != null) {
            dataBufferStream_.write(dataBuffer_, currentRowPosition_, length);
        }

        for (int i = 0; i < length; i++) {
            dataBuffer_[i] = dataBuffer_[currentRowPosition_ + i];
        }

        position_ = length - (lastValidBytePosition_ - position_);
        lastValidBytePosition_ = length;
    }

    private void adjustColumnOffsetsForColumnsPreviouslyCalculated(int index) {
        for (int j = 0; j <= index; j++) {
            columnDataPosition_[j] -= currentRowPosition_;
        }
    }

    private void resetCurrentRowPosition() {
        currentRowPosition_ = 0;
    }

    // Calculates the column index for Lob objects constructed from EXTDTA data.
    // Describe information isn't sufficient because we have to check
    // for trivial values (nulls or zero-length) and exclude them.
    void calculateLobColumnPositionsForRow() {
        int currentPosition = 0;

        for (int i = 0; i < columns_; i++) {
            if (isNonTrivialDataLob(i))
            // key = column position, data = index to corresponding data in extdtaData_
            // ASSERT: the server always returns the EXTDTA objects in ascending order
            {
                extdtaPositions_.put(new Integer(i + 1), new Integer(currentPosition++));
            }
        }
    }

    // prereq: the base data for the cursor has been processed for offsets and lengths
    boolean isNonTrivialDataLob(int index) {
        long length = 0L;

        if (isNull_[index] ||
                (jdbcTypes_[index] != Types.BLOB &&
                jdbcTypes_[index] != Types.CLOB)) {
            return false;
        }

        int position = columnDataPosition_[index];

        // if the high-order bit is set, length is unknown -> set value to x'FF..FF'
        if (((dataBuffer_[position]) & 0x80) == 0x80) {
            length = -1;
        } else {

            byte[] lengthBytes = new byte[columnDataComputedLength_[index]];
            byte[] longBytes = new byte[8];

            System.arraycopy(dataBuffer_,
                    position,
                    lengthBytes,
                    0,
                    columnDataComputedLength_[index]);

            // right-justify for BIG ENDIAN
            int j = 0;
            for (int i = 8 - columnDataComputedLength_[index]; i < 8; i++) {
                longBytes[i] = lengthBytes[j];
                j++;
            }
            length = SignedBinary.getLong(longBytes, 0);
        }
        return (length != 0L) ? true : false;
    }

    protected void clearLobData_() {
        extdtaData_.clear();
        extdtaPositions_.clear();
    }

    // SQLCARD : FDOCA EARLY ROW
    // SQL Communications Area Row Description
    //
    // FORMAT FOR ALL SQLAM LEVELS
    //   SQLCAGRP; GROUP LID 0x54; ELEMENT TAKEN 0(all); REP FACTOR 1
    NetSqlca parseSQLCARD(Typdef typdef) throws org.apache.derby.client.am.DisconnectException, SqlException {
        return parseSQLCAGRP(typdef);
    }

    // SQLCAGRP : FDOCA EARLY GROUP
    // SQL Communcations Area Group Description
    //
    // FORMAT FOR SQLAM <= 6
    //   SQLCODE; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLSTATE; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 5
    //   SQLERRPROC; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 8
    //   SQLCAXGRP; PROTOCOL TYPE N-GDA; ENVLID 0x52; Length Override 0
    //
    // FORMAT FOR SQLAM >= 7
    //   SQLCODE; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLSTATE; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 5
    //   SQLERRPROC; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 8
    //   SQLCAXGRP; PROTOCOL TYPE N-GDA; ENVLID 0x52; Length Override 0
    //   SQLDIAGGRP; PROTOCOL TYPE N-GDA; ENVLID 0x56; Length Override 0
    private NetSqlca parseSQLCAGRP(Typdef typdef) throws org.apache.derby.client.am.DisconnectException, SqlException {
        if (readFdocaOneByte() == CodePoint.NULLDATA) {
            return null;
        }
        int sqlcode = readFdocaInt();
        byte[] sqlstate = readFdocaBytes(5);
        byte[] sqlerrproc = readFdocaBytes(8);
        NetSqlca netSqlca = new NetSqlca(netAgent_.netConnection_, sqlcode, sqlstate, sqlerrproc, typdef.getCcsidSbc());

        parseSQLCAXGRP(typdef, netSqlca);

        parseSQLDIAGGRP();

        return netSqlca;
    }

    // SQLCAXGRP : EARLY FDOCA GROUP
    // SQL Communications Area Exceptions Group Description
    //
    // FORMAT FOR SQLAM <= 6
    //   SQLRDBNME; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 18
    //   SQLERRD1; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD2; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD3; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD4; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD5; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD6; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLWARN0; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN1; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN2; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN3; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN4; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN5; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN6; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN7; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN8; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN9; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARNA; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLERRMSG_m; PROTOCOL TYPE VCM; ENVLID 0x3E; Length Override 70
    //   SQLERRMSG_s; PROTOCOL TYPE VCS; ENVLID 0x32; Length Override 70
    //
    // FORMAT FOR SQLAM >= 7
    //   SQLERRD1; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD2; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD3; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD4; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD5; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLERRD6; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
    //   SQLWARN0; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN1; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN2; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN3; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN4; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN5; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN6; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN7; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN8; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARN9; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLWARNA; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
    //   SQLRDBNAME; PROTOCOL TYPE VCS; ENVLID 0x32; Length Override 255
    //   SQLERRMSG_m; PROTOCOL TYPE VCM; ENVLID 0x3E; Length Override 70
    //   SQLERRMSG_s; PROTOCOL TYPE VCS; ENVLID 0x32; Length Override 70
    private void parseSQLCAXGRP(Typdef typdef, NetSqlca netSqlca) throws DisconnectException, SqlException {
        if (readFdocaOneByte() == CodePoint.NULLDATA) {
            netSqlca.setContainsSqlcax(false);
            return;
        }


        //   SQLERRD1 to SQLERRD6; PROTOCOL TYPE I4; ENVLID 0x02; Length Override 4
        int[] sqlerrd = new int[6];
        for (int i = 0; i < sqlerrd.length; i++) {
            sqlerrd[i] = readFdocaInt();
        }

        //   SQLWARN0 to SQLWARNA; PROTOCOL TYPE FCS; ENVLID 0x30; Length Override 1
        byte[] sqlwarn = readFdocaBytes(11);

        // skip over the rdbnam for now
        // SQLRDBNAME; PROTOCOL TYPE VCS; ENVLID 0x32; Length Override 255
        parseVCS(typdef);

        //   SQLERRMSG_m; PROTOCOL TYPE VCM; ENVLID 0x3E; Length Override 70
        //   SQLERRMSG_s; PROTOCOL TYPE VCS; ENVLID 0x32; Length Override 70
        int varcharLength = readFdocaTwoByteLength();  // mixed length
        byte[] sqlerrmc = null;
        int sqlerrmcCcsid = 0;
        if (varcharLength != 0) {                    // if mixed
            sqlerrmc = readFdocaBytes(varcharLength);      // read mixed bytes
            sqlerrmcCcsid = typdef.getCcsidMbc();