详细介绍mysql 协议的FieldList命令包及解析

git

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

概况

当mysql客户端使用show column命令时即对应这个FieldList命令包。

mysql通信报文结构

类型	名字	描述
int<3>	payload长度	按照the least significant byte first存储，3个字节的payload和1个字节的序列号组合成报文头
int<1>	序列号
string	payload	报文体，长度即为前面指定的payload长度

FieldList命令包

Payload

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

更多详情 ： http://dev.mysql.com/doc/internals/en/com-field-list.html

FieldList命令包操作

1. FieldList命令包类

/**
 * 
 * <pre><b>mysql field list packet.</b></pre>
 * @author 
 * <pre>seaboat</pre>
 * <pre><b>email: </b>[e-mail]</pre>
 * <pre><b>blog: </b>http://www.php.cn/;/pre>
 * @version 1.0
 * @see http://www.php.cn/
 */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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