一、握手阶段
1.client跟server之间进行tcp三次握手
2.server发送handshake
3.client读取handshake，构建发送auth packet, 其中加密后的pass = encrypt(明文pass, seed, restOfScrambleBuff) ，seed和restOfScrambleBuff由handshake返回
4.server认证auth packet，如果认证成功则发送okpacket，否则返回errorpacket
至此握手完成, client端就可以发送真正的sql命令，进入执行阶段
二、执行阶段
以select查询为例，如sql = "select * from t1 limit 0,10;"
1.client发送command packet (select语句相应的command=COM_QUERY)
2.server执行完毕之后，并返回结果(5个packet)
3.client先读取metadata数据包(前3个packet)
ResultSetHeadPacket(有多少个column) + FieldPacket[columns] + EOFPacket
4.client接着读取真正的数据(后2个packet) RowDataPacket[rows] + EOFPacket
三、握手阶段demo
/**
* Handshake握手阶段
*/
public boolean handshakePhase(BufferedOutputStream out, BufferedInputStream in) throws IOException {
//STEP-1:读取handshake握手包
byte[] buffer = new byte[1024];
int reads = in.read(buffer);
byte[] data = Arrays.copyOf(buffer, reads);
HandshakePacket handshakePacket = new HandshakePacket();
handshakePacket.read(data);
System.out.println(String.format("一、读取handshake数据包， packetId = %d, seed = %s, restOfScrambleBuff = %s\n", handshakePacket.packetId, new String(handshakePacket.seed), new String(handshakePacket.restOfScrambleBuff)));
//STEP-2:发送auth认证包
AuthPacket authPacket = new AuthPacket();
authPacket.packetId = 1;
authPacket.clientFlags = getClientFlags();
authPacket.maxPacketSize = 1024 * 1024 * 16;
authPacket.charsetIndex = handshakePacket.serverCharsetIndex & 0xff;
authPacket.user = USERNAME;
authPacket.password = passwd(PASSWORD, handshakePacket.seed, handshakePacket.restOfScrambleBuff);
authPacket.database = DB;
authPacket.write(out);
out.flush();
System.out.println(String.format("二、发送AuthPacket数据包， username = %s, database = %s.\n", authPacket.user, authPacket.database));
//STEP-3:读取服务器auth的认证响应包，成功为OkPacket,失败为ErrorPacket
buffer = new byte[1024];
reads = in.read(buffer);
data = Arrays.copyOf(buffer, reads);
if (data[4] == OkPacket.FIELD_COUNT) {
OkPacket okPacket = new OkPacket();
okPacket.read(data);
System.out.println("三、auth认证成功. " + okPacket + "\n");
return true;
}
else if (data[4] == ErrorPacket.FIELD_COUNT) {
ErrorPacket errorPacket = new ErrorPacket();
errorPacket.read(data);
System.out.println("三、auth认证失败. " + errorPacket.errno + " " + new String(errorPacket.message) + "\n");
}
return false;
}
四、执行阶段demo
/**
* 真正执行SQL命令阶段
* 1个ResultSet Head Packet (返回有多少个column)
* n个Field Packet (n = column number)
* 1个EOF Packet
* m个Row Data Packet (m = row number)
* 1个EOF Packet
*/
public void executePhase(BufferedOutputStream out, BufferedInputStream in) throws IOException {
//发送SQL命令请求数据包
CommandPacket commandPacket = new CommandPacket();
commandPacket.packetId = 0;
commandPacket.command = CommandPacket.COM_QUERY;
commandPacket.arg = SQL.getBytes();
commandPacket.write(out);
out.flush();
System.out.println("四、发送SQL命令. " + SQL + "\n");
byte[] buffer = new byte[10240];
int reads = in.read(buffer);
ByteBuffer bb = ByteBuffer.wrap(buffer, 0, reads);
//读取ResultSetHeaderPacket
ResultSetHeaderPacket headerPacket = new ResultSetHeaderPacket();
headerPacket.read(bb.array());
int packetLength = headerPacket.packetLength;
int packetId = headerPacket.packetId;
int fieldCount = headerPacket.fieldCount;
System.out.println(String.format("五、读取ResultSetHeaderPacket. packetLength = %d, packetId = %d, fieldCount = %d\n", packetLength, packetId, fieldCount));
bb = clearCurrentPacket(bb, 4 + headerPacket.packetLength);
//读取多个FieldPacket
System.out.println("六、读取FieldPacket信息.......");
System.out.println("----------------------------------------------------------------------------------------");
for (int i = 0; i < fieldCount; i++) {
FieldPacket fieldPacket = new FieldPacket();
fieldPacket.read(bb.array());
//field.type信息可参考io.mycat.config.Fields中定义的常量
System.out.println(new String(fieldPacket.name) + ", " + fieldPacket.type + ", " + fieldPacket.length + " ");
bb = clearCurrentPacket(bb, 4 + fieldPacket.packetLength);
}
System.out.println("----------------------------------------------------------------------------------------\n");
//读取EOFPacket
EOFPacket eofPacket = new EOFPacket();
eofPacket.read(bb.array());
packetLength = eofPacket.packetLength;
packetId = eofPacket.packetId;
int warningCount = eofPacket.warningCount;
int status = eofPacket.status;
System.out.println("七、读取EOFPackage. packetId = " + packetId + " " + "\n");
bb = clearCurrentPacket(bb, 4 + packetLength);
//读取多个RowDataPacket
System.out.println("八、读取RowDataPacket.......");
System.out.println("----------------------------------------------------------------------------------------");
EOFPacket lastEofPacket = null; //最后一个EOFPacket
while(bb.hasRemaining()) {
byte[] array = bb.array();
//读取最后一个EOFPacket
if (array[4] == EOFPacket.FIELD_COUNT) {
lastEofPacket = new EOFPacket();
lastEofPacket.read(array);
break;
}
RowDataPacket rowDataPacket = new RowDataPacket(fieldCount);
rowDataPacket.read(bb.array());
//System.out.println("RowDataPackage. packetId = " + rowDataPacket.packetId + " fieldValues size = " + rowDataPacket.fieldValues.size());
for (int i = 0; i < rowDataPacket.fieldValues.size(); i++) {
byte[] row = rowDataPacket.fieldValues.get(i);
if (row == null) {
System.out.print("null, ");
}
else {
System.out.print(new String(row) + ", ");
}
}
System.out.println();
bb = clearCurrentPacket(bb, 4 + rowDataPacket.packetLength);
}
System.out.println("----------------------------------------------------------------------------------------\n");
//输出最后一个EOFPacket
if (lastEofPacket != null) {
System.out.println("九、读取最后一个EOFPacket. packetId = " + lastEofPacket.packetId);
}
}
