ColumnDefinition package and parsing code details of mysql protocol

git

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

Overview

The ColumnDefinition package is part of the package when the server returns the ResultSet and is used to describe the field information of the result set.

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

ColumnDefinition package

Payload

lenenc_str     catalog
lenenc_str     schema
lenenc_str     table
lenenc_str     org_table
lenenc_str     name
lenenc_str     org_name
lenenc_int     length of fixed-length fields [0c]2              
character set4              
column length1              
type2              
flags1              
decimals2              
filler [00] [00]  if command was COM_FIELD_LIST {
lenenc_int     
length of default-valuesstring[$len]   
default values
  }

More details: http://dev.mysql.com/doc/internals/en/com-query-response.html#column-definition

ColumnCount package class

/**
 * 
 * <pre class="brush:php;toolbar:false"><b>column definition command 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 ColumnDefinitionPacket extends MySQLPacket {
    private static final byte[] DEFAULT_CATALOG = "def".getBytes();    
    private static final byte NEXT_LENGTH = 0x0c;    
    private static final byte[] FILLER = { 00, 00 };    
    public byte[] catalog = DEFAULT_CATALOG;// always "def"
    public byte[] schema;    
    public byte[] table;    
    public byte[] orgTable;    
    public byte[] name;    
    public byte[] orgName;    
    public byte nextLength = NEXT_LENGTH;// always 0x0c
    public int charsetSet;    
    public long length;    
    public int type;    
    public int flags;    
    public byte decimals;    
    public byte[] filler = FILLER;    
    public byte[] defaultValues;    
    public void read(byte[] data) {
        MySQLMessage mm = new MySQLMessage(data);        
        this.packetLength = mm.readUB3();        
        this.packetId = mm.read();        
        this.catalog = mm.readBytesWithLength();        
        this.schema = mm.readBytesWithLength();        
        this.table = mm.readBytesWithLength();        
        this.orgTable = mm.readBytesWithLength();        
        this.name = mm.readBytesWithLength();        
        this.orgName = mm.readBytesWithLength();        
        this.nextLength = mm.read();        
        this.charsetSet = mm.readUB2();        
        this.length = mm.readUB4();        
        this.type = mm.read() & 0xff;        
        this.flags = mm.readUB2();        
        this.decimals = mm.read();        
        this.filler = mm.readBytes(2);        
        if (mm.hasRemaining()) {            
        this.defaultValues = mm.readBytesWithLength();
        }
    }    @Override
    public void write(ByteBuffer buffer) {        
    int size = calcPacketSize();
        BufferUtil.writeUB3(buffer, size);
        buffer.put(packetId);
        BufferUtil.writeWithLength(buffer, catalog, (byte) 0);
        BufferUtil.writeWithLength(buffer, schema, (byte) 0);
        BufferUtil.writeWithLength(buffer, table, (byte) 0);
        BufferUtil.writeWithLength(buffer, orgTable, (byte) 0);
        BufferUtil.writeWithLength(buffer, name, (byte) 0);
        BufferUtil.writeWithLength(buffer, orgName, (byte) 0);
        buffer.put(NEXT_LENGTH);
        BufferUtil.writeUB2(buffer, charsetSet);
        BufferUtil.writeUB4(buffer, length);
        buffer.put((byte) (type & 0xff));
        BufferUtil.writeUB2(buffer, flags);
        buffer.put(decimals);
        buffer.put(FILLER);        
        if (defaultValues != null) {            
        //only use for show columns
            BufferUtil.writeWithLength(buffer, defaultValues);
        }
    }    @Override
    public int calcPacketSize() {        
    int size = (catalog == null ? 1 : BufferUtil.getLength(catalog));
        size += (schema == null ? 1 : BufferUtil.getLength(schema));
        size += (table == null ? 1 : BufferUtil.getLength(table));
        size += (orgTable == null ? 1 : BufferUtil.getLength(orgTable));
        size += (name == null ? 1 : BufferUtil.getLength(name));
        size += (orgName == null ? 1 : BufferUtil.getLength(orgName));
        size += 13;        if (defaultValues != null) {
            size += BufferUtil.getLength(defaultValues);
        }        
        return size;
    }    
    @Override
    protected String getPacketInfo() {        
    return "MySQL Column Definition Packet";
    }

}

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