Initialization DB command package and analysis of mysql protocol

git

https://github.com/sea-boat/mysql-protocol

Overview

mysql connection If you want to change the default schema of the connection, the client can send an initialization DB command package to the server.

mysql communication message structure

##string payloadMessage body, the length is the previously specified payload length

Type	Name	Description
int5bdf4c78156c7953567bb5a0aef2fc53	payload length	Stored according to the least significant byte first, 3-byte payload and 1-byte sequence number combination Into the message header
intf35d6e602fd7d0f0edfa6f7d103c1b57	sequence number

Initialize DB command package

Payload

1              [02] COM_INIT_DBstring[EOF]    schema name

More details: http://dev.mysql.com/doc/internals/en/com-init-db.html

Initialization command package operation

1. Initialization command package

/**
 * 
 * @author seaboat
 * @date 2016-09-25
 * @version 1.0
 * 
email: 849586227@qq.com
 * 
blog: //m.sbmmt.com/;/pre>
 * 
mysql init db packet.
 */public class InitDBPacket extends MySQLPacket {
    public byte[] schema;    public void read(byte[] data) {
        MySQLMessage mm = new MySQLMessage(data);
        packetLength = mm.readUB3();
        packetId = mm.read();
        mm.read(); // skip COM_INIT_DB
        this.schema = mm.readBytes();
    }    public void write(ByteBuffer buffer) {
        BufferUtil.writeUB3(buffer, calcPacketSize());
        buffer.put(packetId);
        buffer.put(COM_INIT_DB);
        buffer.put(schema);
    }    @Override
    public int calcPacketSize() {        int i = 1;
        i += schema.length;        return i;
    }    @Override
    protected String getPacketInfo() {        return "MySQL Init DB Packet";
    }

}

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