querycommandpacket.java

mysql集群

/*
 * 	This program is free software; you can redistribute it and/or modify it under the terms of 
 * the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, 
 * or (at your option) any later version. 
 * 
 * 	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 General Public License for more details. 
 * 	You should have received a copy of the GNU General Public License along with this program; 
 * if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package com.meidusa.amoeba.mysql.net.packet;

import java.io.UnsupportedEncodingException;

import com.meidusa.amoeba.net.packet.AbstractPacketBuffer;

/**
 * 
 * From client to server whenever the client wants the server to do something.
 * <pre>
 * Bytes                        Name
 *  -----                        ----
 *  1                            command
 *  n                            arg
 *  
 *  command:      The most common value is 03 COM_QUERY, because
 *                INSERT UPDATE DELETE SELECT etc. have this code.
 *                The possible values at time of writing (taken
 *                from /include/mysql_com.h for enum_server_command) are:
 *  
 *                #      Name                Associated client function
 *                -      ----                --------------------------
 *  
 *                0x00   COM_SLEEP           (none, this is an internal thread state)
 *                0x01   COM_QUIT            mysql_close
 *                0x02   COM_INIT_DB         mysql_select_db 
 *                0x03   COM_QUERY           mysql_real_query
 *                0x04   COM_FIELD_LIST      mysql_list_fields
 *                0x05   COM_CREATE_DB       mysql_create_db (deprecated)
 *                0x06   COM_DROP_DB         mysql_drop_db (deprecated)
 *                0x07   COM_REFRESH         mysql_refresh
 *                0x08   COM_SHUTDOWN        mysql_shutdown
 *                0x09   COM_STATISTICS      mysql_stat
 *                0x0a   COM_PROCESS_INFO    mysql_list_processes
 *                0x0b   COM_CONNECT         (none, this is an internal thread state)
 *                0x0c   COM_PROCESS_KILL    mysql_kill
 *                0x0d   COM_DEBUG           mysql_dump_debug_info
 *                0x0e   COM_PING            mysql_ping
 *                0x0f   COM_TIME            (none, this is an internal thread state)
 *                0x10   COM_DELAYED_INSERT  (none, this is an internal thread state)
 *                0x11   COM_CHANGE_USER     mysql_change_user
 *                0x12   COM_BINLOG_DUMP     (used by slave server / mysqlbinlog)
 *                0x13   COM_TABLE_DUMP      (used by slave server to get master table)
 *                0x14   COM_CONNECT_OUT     (used by slave to log connection to master)
 *                0x15   COM_REGISTER_SLAVE  (used by slave to register to master)
 *                0x16   COM_STMT_PREPARE    mysql_stmt_prepare
 *                0x17   COM_STMT_EXECUTE    mysql_stmt_execute
 *                0x18   COM_STMT_SEND_LONG_DATA mysql_stmt_send_long_data
 *                0x19   COM_STMT_CLOSE      mysql_stmt_close
 *                0x1a   COM_STMT_RESET      mysql_stmt_reset
 *                0x1b   COM_SET_OPTION      mysql_set_server_option
 *                0x1c   COM_STMT_FETCH      mysql_stmt_fetch
 *  
 *  arg:           The text of the command is just the way the user typed it, there is no processing
 *                 by the client (except removal of the final ';').
 *                 This field is not a null-terminated string; however,
 *                 the size can be calculated from the packet size,
 *                 and the MySQL client appends '\0' when receiving.
 * </pre>
 * 
 * @author <a href=mailto:[e-mail]>Struct chen</a>
 *
 */
public class QueryCommandPacket extends CommandPacket {
	public String arg;
	
	@Override
	public void init(AbstractPacketBuffer myBuffer) {
		super.init(myBuffer);
		MysqlPacketBuffer buffer = (MysqlPacketBuffer)myBuffer;
		String charset = buffer.getConnection().getCharset();
		arg	= (charset == null?buffer.readString():buffer.readString(charset));
	}

	@Override
	public void write2Buffer(AbstractPacketBuffer myBuffer) throws UnsupportedEncodingException {
		super.write2Buffer(myBuffer);
		MysqlPacketBuffer buffer = (MysqlPacketBuffer)myBuffer;
		buffer.writeString(arg);
	}

	@Override
	protected int calculatePacketSize(){
		int packLength = super.calculatePacketSize();
        packLength +=(arg == null? 0 : arg.length() * 2);
		return packLength;
	}
	
}