/** 把BinaryPacket转变成FieldPacket */
public void read(BinaryPacket bin) {
this.packetLength = bin.packetLength;
this.packetId = bin.packetId;
readBody(new MySQLMessage(bin.data));
}
/** 把字节数组转变成FieldPacket */
public void read(byte[] data) {
MySQLMessage mm = new MySQLMessage(data);
this.packetLength = mm.readUB3();
this.packetId = mm.read();
readBody(mm);
}