Java tutorial
package com.tesora.dve.mysqlapi.repl.messages; /* * #%L * Tesora Inc. * Database Virtualization Engine * %% * Copyright (C) 2011 - 2014 Tesora Inc. * %% * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License, version 3, * as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. * #L% */ import io.netty.buffer.ByteBuf; import io.netty.buffer.PooledByteBufAllocator; import io.netty.buffer.Unpooled; import io.netty.util.CharsetUtil; import java.math.BigDecimal; import java.nio.ByteOrder; import org.apache.commons.lang.StringUtils; import org.apache.log4j.Logger; import com.tesora.dve.db.mysql.common.MysqlAPIUtils; import com.tesora.dve.exceptions.PEException; public class MyUserVarLogEvent extends MyLogEventPacket { private static final Logger logger = Logger.getLogger(MyUserVarLogEvent.class); private static final int DIG_PER_DEC1 = 9; private static final int dig2bytes[] = { 0, 1, 1, 2, 2, 3, 3, 4, 4, 4 }; int variableNameLen; String variableName; byte nullByte; MyItemResultCode valueType; int valueCharSet; int valueLen; ByteBuf valueBytes; String variableValue; public enum MyItemResultCode { STRING_RESULT((byte) 0x00), REAL_RESULT((byte) 0x01), INT_RESULT((byte) 0x02), ROW_RESULT( (byte) 0x03), DECIMAL_RESULT((byte) 0x04); private final byte code; MyItemResultCode(byte b) { code = b; } public static MyItemResultCode fromByte(byte b) { for (MyItemResultCode mt : values()) { if (mt.code == b) { return mt; } } return null; } public byte getByteValue() { return code; } } public MyUserVarLogEvent(MyReplEventCommonHeader ch) { super(ch); } @Override public void accept(ReplicationVisitorTarget visitorTarget) throws PEException { visitorTarget.visit((MyUserVarLogEvent) this); } @Override public void unmarshallMessage(ByteBuf cb) throws PEException { variableNameLen = cb.readInt(); variableName = MysqlAPIUtils.readBytesAsString(cb, variableNameLen, CharsetUtil.UTF_8); nullByte = cb.readByte(); if (nullByte != 1) { variableValue = processVariableValue(cb); } else { variableValue = "NULL"; } } String processVariableValue(ByteBuf cb) throws PEException { String value = StringUtils.EMPTY; valueType = MyItemResultCode.fromByte(cb.readByte()); valueCharSet = cb.readInt(); valueLen = cb.readInt(); valueBytes = Unpooled.buffer(cb.readableBytes()).order(ByteOrder.LITTLE_ENDIAN); valueBytes.writeBytes(cb); switch (valueType) { case DECIMAL_RESULT: value = processDecimalValue(valueBytes, valueLen); break; case INT_RESULT: value = processIntValue(valueBytes, valueLen); break; case REAL_RESULT: value = Double.toString(valueBytes.readDouble()); break; case STRING_RESULT: value = "'" + StringUtils.replace( MysqlAPIUtils.readBytesAsString(valueBytes, valueLen, CharsetUtil.UTF_8), "'", "''") + "'"; break; case ROW_RESULT: default: throw new PEException( "Unsupported variable type '" + valueType + "' for variable '" + variableName + "'"); } return value; } String processDecimalValue(ByteBuf cb, int valueLen) throws PEException { String value = StringUtils.EMPTY; byte precision = cb.readByte(); byte scale = cb.readByte(); int intg = (int) precision - (int) scale; int intg0 = intg / DIG_PER_DEC1; int frac0 = (int) scale / DIG_PER_DEC1; int intg0x = intg - intg0 * DIG_PER_DEC1; int frac0x = (int) scale - frac0 * DIG_PER_DEC1; int firstValue = intg0 * 4 + dig2bytes[intg0x]; int secondValue = frac0 * 4 + dig2bytes[frac0x]; int binSize = firstValue + secondValue; int readableBytes = cb.readableBytes(); if ((firstValue < 1 && secondValue < 1) || readableBytes < binSize) { throw new PEException("Cannot decode binary decimal"); } ByteBuf chunk = PooledByteBufAllocator.DEFAULT.heapBuffer(binSize); cb.readBytes(chunk); // 1st byte is special cause it determines the sign byte firstByte = chunk.getByte(0); int sign = (firstByte & 0x80) == 0x80 ? 1 : -1; // invert sign chunk.setByte(0, (firstByte ^ 0x80)); if (sign == -1) { // invert all the bytes for (int i = 0; i < binSize; i++) { chunk.setByte(i, ~chunk.getByte(i)); } } BigDecimal integerPortion = decodeBinDecimal(chunk, firstValue, true); BigDecimal fractionPortion = decodeBinDecimal(chunk, secondValue, false); value = ((sign == -1) ? "-" : StringUtils.EMPTY) + integerPortion.toPlainString() + "." + fractionPortion.toPlainString(); return value; } BigDecimal decodeBinDecimal(ByteBuf cb, int bufferLen, boolean isIntegerPortion) throws PEException { BigDecimal decimalPortion = new BigDecimal(0); if (bufferLen > 0) { ByteBuf decimalPortionBuf = cb.readBytes(bufferLen); if (isIntegerPortion) { int initialBytes = bufferLen % 4; if (initialBytes > 0) { long intValue = readValue(decimalPortionBuf, initialBytes); decimalPortion = BigDecimal.valueOf(intValue); } } int decimalPortionLen = decimalPortionBuf.readableBytes(); while (decimalPortionLen > 0) { int nextLen = (decimalPortionLen < 4) ? decimalPortionLen : 4; long intValue = readValue(decimalPortionBuf, nextLen); if (intValue > 0) { if (decimalPortion.longValue() == 0) { decimalPortion = decimalPortion.add(BigDecimal.valueOf(intValue)); } else { int digits = (int) (Math.log10(intValue) + 1); decimalPortion = decimalPortion.movePointRight(digits).add(BigDecimal.valueOf(intValue)); } } decimalPortionLen = decimalPortionBuf.readableBytes(); } } return decimalPortion; } long readValue(ByteBuf decimalPortionBuf, int valueLen) throws PEException { if (valueLen < 1 || valueLen > 4) throw new PEException("Cannot decode decimal buffer. Invalid read length of " + valueLen); long value = 0; if (valueLen == 4) { value = decimalPortionBuf.readUnsignedInt(); } else if (valueLen == 3) { value = decimalPortionBuf.readUnsignedMedium(); } else if (valueLen == 2) { value = decimalPortionBuf.readUnsignedShort(); } else if (valueLen == 1) { value = decimalPortionBuf.readUnsignedByte(); } return value; } String processIntValue(ByteBuf cb, int valueLen) throws PEException { String value = StringUtils.EMPTY; switch (valueLen) { case 8: value = Long.toString(cb.readLong()); break; case 7: case 6: case 5: throw new PEException( "Cannot decode INT value of length '" + valueLen + "' for variable '" + variableName + "'"); case 4: value = Long.toString(cb.readInt()); break; case 3: value = Long.toString(cb.readMedium()); break; case 2: value = Long.toString(cb.readShort()); break; case 1: value = Byte.toString(cb.readByte()); break; } return value; } @Override public void marshallMessage(ByteBuf cb) { cb.writeInt(variableNameLen); cb.writeBytes(variableName.getBytes(CharsetUtil.UTF_8)); cb.writeByte(nullByte); if (nullByte != 1) { cb.writeByte(valueType.getByteValue()); cb.writeInt(valueCharSet); cb.writeInt(valueLen); cb.writeBytes(valueBytes); } } public String getVariableName() { return variableName; } public String getVariableValue() { return variableValue; } }