五、RabbitMQ-客户端源码之AMQChannel

AMQChannel是一个抽象类，是ChannelN的父类。其中包含唯一的抽象方法：

/**
 * Protected API - called by nextCommand to check possibly handle an incoming Command before it is returned to the caller of nextCommand. If this method
 * returns true, the command is considered handled and is not passed back to nextCommand's caller; if it returns false, nextCommand returns the command as
 * usual. This is used in subclasses to implement handling of Basic.Return and Basic.Deliver messages, as well as Channel.Close and Connection.Close.
 * @param command the command to handle asynchronously
 * @return true if we handled the command; otherwise the caller should consider it "unhandled"
 */
public abstract boolean processAsync(Command command) throws IOException;

有关processAsync()这个方法的会在介绍ChannelN类的时候详细阐述（[[八]RabbitMQ-客户端源码之ChannelN][RabbitMQ-_ChannelN]）。

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首先来说下AMQChannel的成员变量：

protected final Object _channelMutex = new Object();
/** The connection this channel is associated with. */
private final AMQConnection _connection;
/** This channel's channel number. */
private final int _channelNumber;
/** Command being assembled */
private AMQCommand _command = new AMQCommand();
/** The current outstanding RPC request, if any. (Could become a queue in future.) */
private RpcContinuation _activeRpc = null;
/** Whether transmission of content-bearing methods should be blocked */
public volatile boolean _blockContent = false;