Detailed introduction to the FieldList command package and analysis of the mysql protocol

git

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

Overview

When the mysql client uses the show column command, it corresponds to this FieldList command package.

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

FieldList command package

Payload

1              [04] COM_FIELD_LISTstring[NUL]    tablestring[EOF]    field wildcard

More details: http://dev.mysql.com/doc/internals/en/com-field-list.html

FieldList command package operation

1. FieldList command package class

/**
 * 
 * 
mysql field list packet.
 * @author 
 * 
seaboat
 * 
email: 849586227@qq.com
 * 
blog: //m.sbmmt.com/;/pre>
 * @version 1.0
 * @see //m.sbmmt.com/
 */public class FieldListPacket extends MySQLPacket {
    public byte flag;    public byte[] table;    public byte[] fieldWildcard;    @Override
    public void read(byte[] data) {
        MySQLMessage mm = new MySQLMessage(data);
        packetLength = mm.readUB3();
        packetId = mm.read();
        flag = mm.read();
        table = mm.readBytesWithNull();
        fieldWildcard = mm.readBytes();
    }    @Override
    public void write(ByteBuffer buffer) {
        BufferUtil.writeUB3(buffer, calcPacketSize());
        buffer.put(packetId);
        buffer.put(COM_FIELD_LIST);
        BufferUtil.writeWithNull(buffer, table);
        buffer.put(fieldWildcard);
    }    @Override
    public int calcPacketSize() {        int i = 1;
        i += table.length + 1;
        i += fieldWildcard.length;        return i;
    }    @Override
    protected String getPacketInfo() {        return "MySQL Field List Packet";
    }

}

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