Mina Io监听器接口定义及抽象实现

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Mina IoService接口定义及抽象实现: http://donald-draper.iteye.com/blog/2378271
引言:
    上面我们看了IoService接口的定义及抽象实现,先来回顾一下:
    抽象service关联一个IoHandler处理会话相关事件,关联一个执行器Executor,负责处理io事件的执行,一个会话配置IOsessionConfig,用于service创建会话时,配置会话,一个过滤链构建器IoFilterChainBuilder,用于构建会话的过滤链,会话数据结构工厂,用于创建会话的属性Map和写请求队列,还有service监听器和统计器。抽象service构造,首先检查会话配置和传输元数据,会话配置必须传输元数据的会话配置类型必须相同,即socket(TCP),会话配置为socketSessionConfig,报文通信(UDP),为DatagramSessionConfig;然后将会话创建监听器serviceActivationListener添加监听器管理器IoServiceListenerSupport;初始化会话配置,IO事件执行器executor和异常监视器。初始化会话就是将service会话数据结构工厂的会话属性添加到具体的会话中,将service会话数据结构工厂的写请求队列,设置到具体的会话中,如果是连接请求会话,则将连接结果添加会话属性中。
今天我们我们来看一下IoService的一个分支IoAcceptor:
/**
 * Accepts incoming connection, communicates with clients, and fires events to
 * {@link IoHandler}s.
 接收连接请求,与客户端通信,触发IoHandler相关事件。
 * 

* Please refer to * [url=../../../../../xref-examples/org/apache/mina/examples/echoserver/Main.html]EchoServer[/url] * example. *

* You should bind to the desired socket address to accept incoming * connections, and then events for incoming connections will be sent to * the specified default {@link IoHandler}. *

你应该绑定socket地址,以接收连接请求,连接请求事件将会发送个默认的IoHandler。 * Threads accept incoming connections start automatically when * {@link #bind()} is invoked, and stop when {@link #unbind()} is invoked. *当IoAcceptor绑定地址时,相关线程将自动开始接收连接请求,当调用#unbind方法,将停止 线程接收连接请求 * @author [url=http://mina.apache.org]Apache MINA Project[/url] */ public interface IoAcceptor extends IoService { /** * Returns the local address which is bound currently. If more than one * address are bound, only one of them will be returned, but it's not * necessarily the firstly bound address. * 返回当前绑定本地地址,当绑定多个地址时,返回其中一个,不需要非是第一个绑定的地址 * @return The bound LocalAddress */ SocketAddress getLocalAddress(); /** * Returns a {@link Set} of the local addresses which are bound currently. * 返回绑定的地址集 * @return The Set of bound LocalAddresses */ Set getLocalAddresses(); /** * Returns the default local address to bind when no argument is specified * in {@link #bind()} method. Please note that the default will not be * used if any local address is specified. If more than one address are * set, only one of them will be returned, but it's not necessarily the * firstly specified address in {@link #setDefaultLocalAddresses(List)}. * 当bind无参方法被调用时,返回一个默认的本地地址。 * @return The default bound LocalAddress */ SocketAddress getDefaultLocalAddress(); /** * Returns a {@link List} of the default local addresses to bind when no * argument is specified in {@link #bind()} method. Please note that the * default will not be used if any local address is specified. * 返回默认地址集 * @return The list of default bound LocalAddresses */ List getDefaultLocalAddresses(); /** * Sets the default local address to bind when no argument is specified in * {@link #bind()} method. Please note that the default will not be used * if any local address is specified. *设置默认socket地址 * @param localAddress The local addresses to bind the acceptor on */ void setDefaultLocalAddress(SocketAddress localAddress); /** * Sets the default local addresses to bind when no argument is specified * in {@link #bind()} method. Please note that the default will not be * used if any local address is specified. 设置默认地址集 * @param firstLocalAddress The first local address to bind the acceptor on * @param otherLocalAddresses The other local addresses to bind the acceptor on */ void setDefaultLocalAddresses(SocketAddress firstLocalAddress, SocketAddress... otherLocalAddresses); /** * Sets the default local addresses to bind when no argument is specified * in {@link #bind()} method. Please note that the default will not be * used if any local address is specified. * * @param localAddresses The local addresses to bind the acceptor on */ void setDefaultLocalAddresses(Iterable localAddresses); /** * Sets the default local addresses to bind when no argument is specified * in {@link #bind()} method. Please note that the default will not be * used if any local address is specified. * * @param localAddresses The local addresses to bind the acceptor on */ void setDefaultLocalAddresses(List localAddresses); /** * Returns true if and only if all clients are closed when this * acceptor unbinds from all the related local address (i.e. when the * service is deactivated). 当且仅当所有客户端关闭,acceptor解绑所有相关本地地址 * * @return true if the service sets the closeOnDeactivation flag */ boolean isCloseOnDeactivation(); /** * Sets whether all client sessions are closed when this acceptor unbinds * from all the related local addresses (i.e. when the service is * deactivated). The default value is true. * 无论所有客户端关闭是否,acceptor是否解绑所有相关本地地址,设置closeOnDeactivation * @param closeOnDeactivation true if we should close on deactivation */ void setCloseOnDeactivation(boolean closeOnDeactivation); /** * Binds to the default local address(es) and start to accept incoming * connections. *绑定默认的socket本地地址,接收连接请求 * @throws IOException if failed to bind */ void bind() throws IOException; /** * Binds to the specified local address and start to accept incoming * connections. *绑定socket本地地址,接收连接请求 * @param localAddress The SocketAddress to bind to * * @throws IOException if failed to bind */ void bind(SocketAddress localAddress) throws IOException; /** * Binds to the specified local addresses and start to accept incoming * connections. If no address is given, bind on the default local address. * 绑定socket本地地址,接收连接请求,如果没给给定参数,绑定默认地址 * @param firstLocalAddress The first address to bind to * @param addresses The SocketAddresses to bind to * * @throws IOException if failed to bind */ void bind(SocketAddress firstLocalAddress, SocketAddress... addresses) throws IOException; /** * Binds to the specified local addresses and start to accept incoming * connections. If no address is given, bind on the default local address. * 绑定socket本地地址,接收连接请求,如果没给给定参数,绑定默认地址 * @param addresses The SocketAddresses to bind to * * @throws IOException if failed to bind */ void bind(SocketAddress... addresses) throws IOException; /** * Binds to the specified local addresses and start to accept incoming * connections. *绑定socket本地地址,接收连接请求,如果没给给定参数,绑定默认地址 * @param localAddresses The local address we will be bound to * @throws IOException if failed to bind */ void bind(Iterable localAddresses) throws IOException; /** * Unbinds from all local addresses that this service is bound to and stops * to accept incoming connections. All managed connections will be closed * if {@link #setCloseOnDeactivation(boolean) disconnectOnUnbind} property * is true. This method returns silently if no local address is * bound yet. 解绑service绑定的所有本地socket地址,停止接收,连接请求。如果CloseOnDeactivation参数为 解绑时,断开连接,则关闭service管理的所有会话。 */ void unbind(); /** * Unbinds from the specified local address and stop to accept incoming * connections. All managed connections will be closed if * {@link #setCloseOnDeactivation(boolean) disconnectOnUnbind} property is * true. This method returns silently if the default local * address is not bound yet. * 解绑service绑定的所有本地socket地址,停止接收,连接请求。如果CloseOnDeactivation参数为 解绑时,断开连接,则关闭service管理的所有会话。 * @param localAddress The local address we will be unbound from */ void unbind(SocketAddress localAddress); /** * Unbinds from the specified local addresses and stop to accept incoming * connections. All managed connections will be closed if * {@link #setCloseOnDeactivation(boolean) disconnectOnUnbind} property is * true. This method returns silently if the default local * addresses are not bound yet. * 解绑service绑定的所有本地socket地址,停止接收,连接请求。如果CloseOnDeactivation参数为 解绑时,断开连接,则关闭service管理的所有会话。 * @param firstLocalAddress The first local address to be unbound from * @param otherLocalAddresses The other local address to be unbound from */ void unbind(SocketAddress firstLocalAddress, SocketAddress... otherLocalAddresses); /** * Unbinds from the specified local addresses and stop to accept incoming * connections. All managed connections will be closed if * {@link #setCloseOnDeactivation(boolean) disconnectOnUnbind} property is * true. This method returns silently if the default local * addresses are not bound yet. * 解绑service绑定的所有本地socket地址,停止接收,连接请求。如果CloseOnDeactivation参数为 解绑时,断开连接,则关闭service管理的所有会话。 * @param localAddresses The local address we will be unbound from */ void unbind(Iterable localAddresses); /** * (Optional) Returns an {@link IoSession} that is bound to the specified * localAddress and the specified remoteAddress which * reuses the local address that is already bound by this service. 返回绑定本地地址和远端socket地址的会话,本地地址,service已绑定,并可以重用 *

* This operation is optional. Please throw {@link UnsupportedOperationException} * if the transport type doesn't support this operation. This operation is * usually implemented for connectionless transport types. *操作时可选的,如果transport不支持此操作,则可抛出UnsupportedOperationException, 此操作一般报文通信会实现 * @param remoteAddress The remote address bound to the service * @param localAddress The local address the session will be bound to * @throws UnsupportedOperationException if this operation is not supported * @throws IllegalStateException if this service is not running. * @throws IllegalArgumentException if this service is not bound to the * specified localAddress. * @return The session bound to the the given localAddress and remote address */ IoSession newSession(SocketAddress remoteAddress, SocketAddress localAddress); }


从IoAcceptor的接口定义可以看,IoAcceptor是将IoService添加了监听连接请求功能。
再来看抽象实现:
/**
 * A base implementation of {@link IoAcceptor}.
 *
 * @author [url=http://mina.apache.org]Apache MINA Project[/url]
 * @org.apache.xbean.XBean
 */
public abstract class AbstractIoAcceptor extends AbstractIoService implements IoAcceptor {
    private final List defaultLocalAddresses = new ArrayList<>();//默认绑定的socket地址集
    private final List unmodifiableDefaultLocalAddresses = Collections
            .unmodifiableList(defaultLocalAddresses);//包装默认的地址集为不可修改集合
    private final Set boundAddresses = new HashSet<>();//绑定地址集
    private boolean disconnectOnUnbind = true;
    /**
     * The lock object which is acquired while bind or unbind operation is performed.
     * Acquire this lock in your property setters which shouldn't be changed while
     * the service is bound.
     */
    protected final Object bindLock = new Object();
    
    /**
     * Constructor for {@link AbstractIoAcceptor}. You need to provide a default
     * session configuration and an {@link Executor} for handling I/O events. If
     * null {@link Executor} is provided, a default one will be created using
     * {@link Executors#newCachedThreadPool()}.
     * 根据会话配置和执行器构造抽象Io接收器
     * @see AbstractIoService#AbstractIoService(IoSessionConfig, Executor)
     * 
     * @param sessionConfig
     *            the default configuration for the managed {@link IoSession}
     * @param executor
     *            the {@link Executor} used for handling execution of I/O
     *            events. Can be null.
     */
    protected AbstractIoAcceptor(IoSessionConfig sessionConfig, Executor executor) {
        super(sessionConfig, executor);
        defaultLocalAddresses.add(null);
    }
}

来看一下地址绑定操作:
  /**
     * {@inheritDoc}
     */
    @Override
    public final void bind() throws IOException {
        bind(getDefaultLocalAddresses());
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public final void bind(SocketAddress localAddress) throws IOException {
        if (localAddress == null) {
            throw new IllegalArgumentException("localAddress");
        }
        
        List localAddresses = new ArrayList<>(1);
        localAddresses.add(localAddress);
        bind(localAddresses);
    }
    /**
     * {@inheritDoc}
     */
    @Override
    public final void bind(SocketAddress... addresses) throws IOException {
        if ((addresses == null) || (addresses.length == 0)) {
            bind(getDefaultLocalAddresses());
            return;
        }
        List localAddresses = new ArrayList<>(2);

        for (SocketAddress address : addresses) {
            localAddresses.add(address);
        }
        bind(localAddresses);
    }
    /**
     * {@inheritDoc}
     */
    @Override
    public final void bind(SocketAddress firstLocalAddress, SocketAddress... addresses) throws IOException {
        if (firstLocalAddress == null) {
            bind(getDefaultLocalAddresses());
        }
        if ((addresses == null) || (addresses.length == 0)) {
            bind(getDefaultLocalAddresses());
            return;
        }
        List localAddresses = new ArrayList<>(2);
        localAddresses.add(firstLocalAddress);

        for (SocketAddress address : addresses) {
            localAddresses.add(address);
        }
        bind(localAddresses);
    }
以上的绑定方法,实际由bind(Iterable localAddresses)完成。

    /**
     * {@inheritDoc}
     */
    @Override
public final void bind(Iterable localAddresses) throws IOException {
        if (isDisposing()) {
            throw new IllegalStateException("The Accpetor disposed is being disposed.");
        }
        if (localAddresses == null) {
            throw new IllegalArgumentException("localAddresses");
        }
        List localAddressesCopy = new ArrayList<>();
        for (SocketAddress a : localAddresses) {
            checkAddressType(a);//检查地址类
            localAddressesCopy.add(a);
        }
        if (localAddressesCopy.isEmpty()) {
            throw new IllegalArgumentException("localAddresses is empty.");
        }
        boolean activate = false;
	//同步绑定锁和地址绑定集合
        synchronized (bindLock) {
            synchronized (boundAddresses) {
                if (boundAddresses.isEmpty()) {
                    activate = true;
                }
            }
            if (getHandler() == null) {
                throw new IllegalStateException("handler is not set.");
            }
            try {
	        //完成实际绑定
                Set addresses = bindInternal(localAddressesCopy);
                synchronized (boundAddresses) {
		   //将绑定地址添加到绑定集合boundAddresses
                    boundAddresses.addAll(addresses);
                }
            } catch (IOException | RuntimeException e) {
                throw e;
            } catch (Exception e) {
                throw new RuntimeIoException("Failed to bind to: " + getLocalAddresses(), e);
            }
        }
        if (activate) {
	   //通知Service监听器,Service已激活
            getListeners().fireServiceActivated();
        }
    }

绑定方法有以下几点要看
 1.
  checkAddressType(a);//检查地址类

 private void checkAddressType(SocketAddress a) {
       //检查绑定的socket地址与传输元数据的地址类型是否相同
        if (a != null && !getTransportMetadata().getAddressType().isAssignableFrom(a.getClass())) {
            throw new IllegalArgumentException("localAddress type: " + a.getClass().getSimpleName() + " (expected: "
                    + getTransportMetadata().getAddressType().getSimpleName() + ")");
        }
    }

 2.
 //完成实际绑定
 Set addresses = bindInternal(localAddressesCopy); 

/**
     * Starts the acceptor, and register the given addresses
     * 待子类扩展,启动监听器,注册地址
     * @param localAddresses The address to bind to
     * @return the {@link Set} of the local addresses which is bound actually
     * @throws Exception If the bind failed
     */
protected abstract Set bindInternal(List localAddresses) throws Exception;

从上面可以看出,绑定地址首先要检查绑定的socket地址与传输元数据的地址类型是否相同,相同则通过bindInternal完成实际的绑定,然后通知Service监听器,Service已激活fireServiceActivated。
再来看地址解绑:
/**
     * {@inheritDoc}
     */
    @Override
    public final void unbind() {
        unbind(getLocalAddresses());
    }
    /**
     * {@inheritDoc}
     */
    @Override
    public final void unbind(SocketAddress localAddress) {
        if (localAddress == null) {
            throw new IllegalArgumentException("localAddress");
        }

        List localAddresses = new ArrayList<>(1);
        localAddresses.add(localAddress);
        unbind(localAddresses);
    }
    /**
     * {@inheritDoc}
     */
    @Override
    public final void unbind(SocketAddress firstLocalAddress, SocketAddress... otherLocalAddresses) {
        if (firstLocalAddress == null) {
            throw new IllegalArgumentException("firstLocalAddress");
        }
        if (otherLocalAddresses == null) {
            throw new IllegalArgumentException("otherLocalAddresses");
        }

        List localAddresses = new ArrayList<>();
        localAddresses.add(firstLocalAddress);
        Collections.addAll(localAddresses, otherLocalAddresses);
        unbind(localAddresses);
    }

上面所有的解绑方法实际通过unbind(Iterable localAddresses)方法完成:
  
 /**
     * {@inheritDoc}
     */
    @Override
    public final void unbind(Iterable localAddresses) {
        if (localAddresses == null) {
            throw new IllegalArgumentException("localAddresses");
        }
        boolean deactivate = false;
	//同步绑定锁和绑定地址集合
        synchronized (bindLock) {
            synchronized (boundAddresses) {
                if (boundAddresses.isEmpty()) {
                    return;
                }
                List localAddressesCopy = new ArrayList<>();
                int specifiedAddressCount = 0;
                for (SocketAddress a : localAddresses) {
                    specifiedAddressCount++;

                    if ((a != null) && boundAddresses.contains(a)) {
                        localAddressesCopy.add(a);
                    }
                }
                if (specifiedAddressCount == 0) {
                    throw new IllegalArgumentException("localAddresses is empty.");
                }
                if (!localAddressesCopy.isEmpty()) {
                    try {
                        unbind0(localAddressesCopy);
                    } catch (RuntimeException e) {
                        throw e;
                    } catch (Exception e) {
                        throw new RuntimeIoException("Failed to unbind from: " + getLocalAddresses(), e);
                    }
		    //清空绑定地址集合
                    boundAddresses.removeAll(localAddressesCopy);
                    if (boundAddresses.isEmpty()) {
                        deactivate = true;
                    }
                }
            }
        }
        if (deactivate) {
	    //触发Service监听器无效事件
            getListeners().fireServiceDeactivated();
        }
    }

/**
 * Implement this method to perform the actual unbind operation.
 * 待子类实现,具体解绑
 * @param localAddresses The address to unbind from
 * @throws Exception If the unbind failed
 */
protected abstract void unbind0(List localAddresses) throws Exception;

从解绑地址方法来看,主要是委托unbind0方法完成实际解绑工作,清空绑定地址集合boundAddresses,触发Service监听器无效事件fireServiceDeactivated。
再来看其他方法,下面这些方法就不讲了,都是set和get操作看看就行:
  /**
     * {@inheritDoc}
     */
    @Override
    public SocketAddress getLocalAddress() {
        Set localAddresses = getLocalAddresses();
        if (localAddresses.isEmpty()) {
            return null;
        }

        return localAddresses.iterator().next();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public final Set getLocalAddresses() {
        Set localAddresses = new HashSet<>();

        synchronized (boundAddresses) {
            localAddresses.addAll(boundAddresses);
        }

        return localAddresses;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public SocketAddress getDefaultLocalAddress() {
        if (defaultLocalAddresses.isEmpty()) {
            return null;
        }
        return defaultLocalAddresses.iterator().next();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public final void setDefaultLocalAddress(SocketAddress localAddress) {
        setDefaultLocalAddresses(localAddress);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public final List getDefaultLocalAddresses() {
        return unmodifiableDefaultLocalAddresses;
    }

    /**
     * {@inheritDoc}
     * @org.apache.xbean.Property nestedType="java.net.SocketAddress"
     */
    @Override
    public final void setDefaultLocalAddresses(List localAddresses) {
        if (localAddresses == null) {
            throw new IllegalArgumentException("localAddresses");
        }
        setDefaultLocalAddresses((Iterable) localAddresses);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public final void setDefaultLocalAddresses(Iterable localAddresses) {
        if (localAddresses == null) {
            throw new IllegalArgumentException("localAddresses");
        }

        synchronized (bindLock) {
            synchronized (boundAddresses) {
                if (!boundAddresses.isEmpty()) {
                    throw new IllegalStateException("localAddress can't be set while the acceptor is bound.");
                }

                Collection newLocalAddresses = new ArrayList<>();

                for (SocketAddress a : localAddresses) {
                    checkAddressType(a);
                    newLocalAddresses.add(a);
                }

                if (newLocalAddresses.isEmpty()) {
                    throw new IllegalArgumentException("empty localAddresses");
                }

                this.defaultLocalAddresses.clear();
                this.defaultLocalAddresses.addAll(newLocalAddresses);
            }
        }
    }

    /**
     * {@inheritDoc}
     * @org.apache.xbean.Property nestedType="java.net.SocketAddress"
     */
    @Override
    public final void setDefaultLocalAddresses(SocketAddress firstLocalAddress, SocketAddress... otherLocalAddresses) {
        if (otherLocalAddresses == null) {
            otherLocalAddresses = new SocketAddress[0];
        }

        Collection newLocalAddresses = new ArrayList<>(otherLocalAddresses.length + 1);

        newLocalAddresses.add(firstLocalAddress);
        
        for (SocketAddress a : otherLocalAddresses) {
            newLocalAddresses.add(a);
        }

        setDefaultLocalAddresses(newLocalAddresses);
    }
    /**
     * {@inheritDoc}
     */
    @Override
    public final boolean isCloseOnDeactivation() {
        return disconnectOnUnbind;
    }
    /**
     * {@inheritDoc}
     */
    @Override
    public final void setCloseOnDeactivation(boolean disconnectClientsOnUnbind) {
        this.disconnectOnUnbind = disconnectClientsOnUnbind;
    }

 
  /**
     * A {@Link IoFuture} 
     监听操作结果
     */
    public static class AcceptorOperationFuture extends ServiceOperationFuture {
        private final List localAddresses;

        /**
         * Creates a new AcceptorOperationFuture instance
         * 
         * @param localAddresses The list of local addresses to listen to
         */
        public AcceptorOperationFuture(List localAddresses) {
            this.localAddresses = new ArrayList<>(localAddresses);
        }
        /**
         * @return The list of local addresses we listen to
         */
        public final List getLocalAddresses() {
            return Collections.unmodifiableList(localAddresses);
        }
        /**
         * @see Object#toString()
         */
        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder();

            sb.append("Acceptor operation : ");

            if (localAddresses != null) {
                boolean isFirst = true;

                for (SocketAddress address : localAddresses) {
                    if (isFirst) {
                        isFirst = false;
                    } else {
                        sb.append(", ");
                    }

                    sb.append(address);
                }
            }
            return sb.toString();
        }
    }
}


总结;
IoAcceptor与IoService不同的是,添加了监听连接请求和地址绑定功能。抽象Io监听器AbstractIoAcceptor绑定地址首先要检查绑定的socket地址与传输元数据的地址类型是否相同,相同则通过bindInternal完成实际的绑定,然后通知Service监听器,Service已激活fireServiceActivated。解绑地址方法,主要是委托unbind0方法完成实际解绑工作,清空绑定地址集合boundAddresses,触发Service监听器无效事件fireServiceDeactivated。

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