| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.client.net.NetSqldta |
| 4 | |
| 5 | Copyright (c) 2001, 2005 The Apache Software Foundation or its licensors, where applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.client.net; |
| 22 | |
| 23 | |
| 24 | public class NetSqldta extends NetCursor { |
| 25 | private NetConnection netConnection_; |
| 26 | |
| 27 | |
| 28 | public NetSqldta(NetAgent netAgent) { |
| 29 | super(netAgent); |
| 30 | netConnection_ = netAgent.netConnection_; |
| 31 | } |
| 32 | |
| 33 | public boolean next() throws org.apache.derby.client.am.SqlException { |
| 34 | if (allRowsReceivedFromServer()) { |
| 35 | return false; |
| 36 | } else { |
| 37 | setAllRowsReceivedFromServer(true); |
| 38 | return true; |
| 39 | } |
| 40 | } |
| 41 | |
| 42 | protected boolean calculateColumnOffsetsForRow() { |
| 43 | int colNullIndicator = CodePoint.NULLDATA; |
| 44 | int length; |
| 45 | |
| 46 | extdtaPositions_.clear(); // reset positions for this row |
| 47 | |
| 48 | // read the da null indicator |
| 49 | if (readFdocaOneByte() == 0xff) { |
| 50 | return false; |
| 51 | } |
| 52 | |
| 53 | incrementRowsReadEvent(); |
| 54 | // Use the arrays defined on the Cursor for forward-only cursors. |
| 55 | // can they ever be null |
| 56 | if (columnDataPosition_ == null || columnDataComputedLength_ == null || isNull_ == null) { |
| 57 | allocateColumnOffsetAndLengthArrays(); |
| 58 | } |
| 59 | |
| 60 | // Loop through the columns |
| 61 | for (int index = 0; index < columns_; index++) { |
| 62 | // If column is nullable, read the 1-byte null indicator. |
| 63 | if (nullable_[index]) |
| 64 | // Need to pass the column index so all previously calculated offsets can be |
| 65 | // readjusted if the query block splits on a column null indicator. |
| 66 | |
| 67 | // null indicators from FD:OCA data |
| 68 | // 0 to 127: a data value will flow. |
| 69 | // -1 to -128: no data value will flow. |
| 70 | { |
| 71 | colNullIndicator = readFdocaOneByte(); |
| 72 | } |
| 73 | |
| 74 | // If non-null column data |
| 75 | if (!nullable_[index] || (colNullIndicator >= 0 && colNullIndicator <= 127)) { |
| 76 | isNull_[index] = false; |
| 77 | |
| 78 | switch (typeToUseForComputingDataLength_[index]) { |
| 79 | // for variable character string and variable byte string, |
| 80 | // there are 2-byte of length in front of the data |
| 81 | case Typdef.TWOBYTELENGTH: |
| 82 | columnDataPosition_[index] = position_; |
| 83 | length = readFdocaTwoByteLength(); |
| 84 | // skip length + the 2-byte length field |
| 85 | if (isGraphic_[index]) { |
| 86 | columnDataComputedLength_[index] = skipFdocaBytes(length * 2) + 2; |
| 87 | } else { |
| 88 | columnDataComputedLength_[index] = skipFdocaBytes(length) + 2; |
| 89 | } |
| 90 | break; |
| 91 | |
| 92 | // for short variable character string and short variable byte string, |
| 93 | // there is a 1-byte length in front of the data |
| 94 | case Typdef.ONEBYTELENGTH: |
| 95 | columnDataPosition_[index] = position_; |
| 96 | length = readFdocaOneByte(); |
| 97 | // skip length + the 1-byte length field |
| 98 | if (isGraphic_[index]) { |
| 99 | columnDataComputedLength_[index] = skipFdocaBytes(length * 2) + 1; |
| 100 | } else { |
| 101 | columnDataComputedLength_[index] = skipFdocaBytes(length) + 1; |
| 102 | } |
| 103 | break; |
| 104 | |
| 105 | // For decimal columns, determine the precision, scale, and the representation |
| 106 | case Typdef.DECIMALLENGTH: |
| 107 | columnDataPosition_[index] = position_; |
| 108 | columnDataComputedLength_[index] = skipFdocaBytes(getDecimalLength(index)); |
| 109 | break; |
| 110 | |
| 111 | case Typdef.LOBLENGTH: |
| 112 | columnDataPosition_[index] = position_; |
| 113 | columnDataComputedLength_[index] = this.skipFdocaBytes(fdocaLength_[index] & 0x7fff); |
| 114 | break; |
| 115 | |
| 116 | default: |
| 117 | columnDataPosition_[index] = position_; |
| 118 | if (isGraphic_[index]) { |
| 119 | columnDataComputedLength_[index] = skipFdocaBytes(fdocaLength_[index] * 2); |
| 120 | } else { |
| 121 | columnDataComputedLength_[index] = skipFdocaBytes(fdocaLength_[index]); |
| 122 | } |
| 123 | break; |
| 124 | } |
| 125 | } else if ((colNullIndicator & 0x80) == 0x80) { |
| 126 | // Null data. Set the isNull indicator to true. |
| 127 | isNull_[index] = true; |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | if (!allRowsReceivedFromServer()) { |
| 132 | calculateLobColumnPositionsForRow(); |
| 133 | } |
| 134 | |
| 135 | return true; // hardwired for now, this means the current row position is a valid position |
| 136 | } |
| 137 | |
| 138 | |
| 139 | private int skipFdocaBytes(int length) { |
| 140 | position_ += length; |
| 141 | return length; |
| 142 | } |
| 143 | |
| 144 | private int readFdocaOneByte() { |
| 145 | return dataBuffer_[position_++] & 0xff; |
| 146 | } |
| 147 | |
| 148 | |
| 149 | private int readFdocaTwoByteLength() { |
| 150 | return |
| 151 | ((dataBuffer_[position_++] & 0xff) << 8) + |
| 152 | ((dataBuffer_[position_++] & 0xff) << 0); |
| 153 | } |
| 154 | |
| 155 | |
| 156 | } |
| 157 | |