Detailed introduction to the ColumnCount package and analysis of the mysql protocol

git

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

Overview

The ColumnCount package is part of the package when the server returns the ResultSet.

mysql communication message structure

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

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

ColumnCount package

Payload

Protocol::LengthEncodedInteger

More details: http://dev.mysql.com/doc/internals/en/com-query-response.html#packet-ProtocolText:: ResultsetRow

ColumnCount package class

/**
 * 
 * <pre class="brush:php;toolbar:false"><b>column count packet.</b>

* @author *

seaboat

*

<b>email: </b>849586227@qq.com

*

<b>blog: </b>http://www.php.cn/;/pre>
 * @version 1.0
 * @see http://www.php.cn/
 */public class ColumnCountPacket extends MySQLPacket {

    public int columnCount;    
    public void read(byte[] data) {
        MySQLMessage mm = new MySQLMessage(data);        
        this.packetLength = mm.readUB3();        
        this.packetId = mm.read();        
        this.columnCount = (int) mm.readLength();
    }    
    @Override
    public void write(ByteBuffer buffer) {        
    int size = calcPacketSize();
        BufferUtil.writeUB3(buffer, size);
        buffer.put(packetId);
        BufferUtil.writeLength(buffer, columnCount);
    }    
    @Override
    public int calcPacketSize() {        
    int size = BufferUtil.getLength(columnCount);        
    return size;
    }    @Override
    protected String getPacketInfo() {        
    return "MySQL Column Count Packet";
    }

}

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