大幅修改框架，分离前后端并捆绑Session，明确单工模式的通讯思路

source/src/main/java/io/mycat/mycat2/AbstractMySQLSession.java

@@ -0,0 +1,183 @@
+package io.mycat.mycat2;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.Selector;
+import java.nio.channels.SocketChannel;
+
+import io.mycat.mycat2.beans.MySQLCharset;
+import io.mycat.mycat2.beans.MySQLPackageInf;
+import io.mycat.mysql.AutoCommit;
+import io.mycat.mysql.Isolation;
+import io.mycat.mysql.packet.MySQLPacket;
+import io.mycat.proxy.AbstractSession;
+import io.mycat.proxy.BufferPool;
+import io.mycat.proxy.ProxyBuffer;
+import io.mycat.proxy.ProxyRuntime;
+import io.mycat.util.ParseUtil;
+import io.mycat.util.StringUtil;
+
+/**
+ * 抽象的MySQL的连接会话
+ * 
+ * @author wuzhihui
+ *
+ */
+public abstract class AbstractMySQLSession extends AbstractSession {
+
+	// 当前接收到的包类型
+	public enum CurrPacketType {
+		Full, LongHalfPacket, ShortHalfPacket
+	}
+
+	/**
+	 * 字符集
+	 */
+	public MySQLCharset charSet;
+	/**
+	 * 用户
+	 */
+	public String clientUser;
+
+	/**
+	 * 事务隔离级别
+	 */
+	public Isolation isolation = Isolation.REPEATED_READ;
+
+	/**
+	 * 事务提交方式
+	 */
+	public AutoCommit autoCommit = AutoCommit.OFF;
+
+	/**
+	 * 认证中的seed报文数据
+	 */
+	public byte[] seed;
+	/**
+	 * 当前处理中的SQL报文的信息
+	 */
+	public MySQLPackageInf curMSQLPackgInf = new MySQLPackageInf();
+
+	public AbstractMySQLSession(BufferPool bufferPool, Selector selector, SocketChannel channel) throws IOException {
+		this(bufferPool, selector, channel, SelectionKey.OP_READ);
+
+
+	}
+
+	public AbstractMySQLSession(BufferPool bufferPool, Selector selector, SocketChannel channel, int keyOpt)
+			throws IOException {
+		super(bufferPool, selector, channel, keyOpt);
+
+	}
+
+	public void setCurBufOwner(boolean curBufOwner) {
+		this.curBufOwner = curBufOwner;
+	}
+
+	/**
+	 * 回应客户端（front或Sever）OK 报文。
+	 *
+	 * @param pkg
+	 *            ，必须要是OK报文或者Err报文
+	 * @throws IOException
+	 */
+	public void responseOKOrError(MySQLPacket pkg) throws IOException {
+		// proxyBuffer.changeOwner(true);
+		pkg.write(this.proxyBuffer);
+		proxyBuffer.flip();
+		proxyBuffer.readIndex = proxyBuffer.writeIndex;
+		this.writeToChannel();
+	}
+
+	/**
+	 * 解析MySQL报文，解析的结果存储在curMSQLPackgInf中，如果解析到完整的报文，就返回TRUE
+	 * 如果解析的过程中同时要移动ProxyBuffer的readState位置，即标记为读过，后继调用开始解析下一个报文，则需要参数markReaded=true
+	 *
+	 * @param proxyBuf
+	 * @return
+	 * @throws IOException
+	 */
+	public CurrPacketType resolveMySQLPackage(ProxyBuffer proxyBuf, MySQLPackageInf curPackInf, boolean markReaded)
+			throws IOException {
+
+		ByteBuffer buffer = proxyBuf.getBuffer();
+		// 读取的偏移位置
+		int offset = proxyBuf.readIndex;
+		// 读取的总长度
+		int limit = proxyBuf.writeIndex;
+		// 读取当前的总长度
+		int totalLen = limit - offset;
+		if (totalLen == 0) { // 透传情况下. 如果最后一个报文正好在buffer 最后位置,已经透传出去了.这里可能不会为零
+			return CurrPacketType.ShortHalfPacket;
+		}
+
+		if (curPackInf.remainsBytes == 0 && curPackInf.crossBuffer) {
+			curPackInf.crossBuffer = false;
+		}
+
+		// 如果当前跨多个报文
+		if (curPackInf.crossBuffer) {
+			if (curPackInf.remainsBytes <= totalLen) {
+				// 剩余报文结束
+				curPackInf.endPos = offset + curPackInf.remainsBytes;
+				offset += curPackInf.remainsBytes; // 继续处理下一个报文
+				proxyBuf.readIndex = offset;
+				curPackInf.remainsBytes = 0;
+			} else {// 剩余报文还没读完，等待下一次读取
+				curPackInf.startPos = 0;
+				curPackInf.remainsBytes -= totalLen;
+				curPackInf.endPos = limit;
+				proxyBuf.readIndex = curPackInf.endPos;
+				return CurrPacketType.LongHalfPacket;
+			}
+		}
+		// 验证当前指针位置是否
+		if (!ParseUtil.validateHeader(offset, limit)) {
+			// 收到短半包
+			logger.debug("not read a whole packet ,session {},offset {} ,limit {}", getSessionId(), offset, limit);
+			return CurrPacketType.ShortHalfPacket;
+		}
+
+		// 解包获取包的数据长度
+		int pkgLength = ParseUtil.getPacketLength(buffer, offset);
+		// 解析报文类型
+		final byte packetType = buffer.get(offset + ParseUtil.msyql_packetHeaderSize);
+		// 包的类型
+		curPackInf.pkgType = packetType;
+		// 设置包的长度
+		curPackInf.pkgLength = pkgLength;
+		// 设置偏移位置
+		curPackInf.startPos = offset;
+
+		curPackInf.crossBuffer = false;
+
+		curPackInf.remainsBytes = 0;
+		// 如果当前需要跨buffer处理
+		if ((offset + pkgLength) > limit) {
+			logger.debug("Not a whole packet: required length = {} bytes, cur total length = {} bytes, limit ={}, "
+					+ "ready to handle the next read event", pkgLength, (limit - offset), limit);
+			curPackInf.endPos = limit;
+			return CurrPacketType.LongHalfPacket;
+		} else {
+			// 读到完整报文
+			curPackInf.endPos = curPackInf.pkgLength + curPackInf.startPos;
+			if (ProxyRuntime.INSTANCE.isTraceProtocol()) {
+				/**
+				 * @todo 跨多个报文的情况下，修正错误。
+				 */
+				final String hexs = StringUtil.dumpAsHex(buffer, curPackInf.startPos, curPackInf.pkgLength);
+				logger.info(
+						"     session {} packet: startPos={}, offset = {}, length = {}, type = {}, cur total length = {},pkg HEX\r\n {}",
+						getSessionId(), curPackInf.startPos, offset, pkgLength, packetType, limit, hexs);
+			}
+			if (markReaded) {
+				proxyBuf.readIndex = curPackInf.endPos;
+			}
+			return CurrPacketType.Full;
+		}
+	}
+
+
+
+}