因为工作中经常使用到TCP,所以会频繁使用到诸如Mina或Netty之类的通信框架,为了方便项目的逻辑调用,经常会在框架的基础上再一次进行封装,这样做其实有画蛇添足的嫌疑,但也是无奈之举。
这里主要记载使用Mina和Netty,构建适合项目的一个完整的重连逻辑。
当然,都是作为客户端,毕竟一般只有客户端才会做重连。
在这之前,需要考虑几个问题:
- 连接行为的结果可以较为方便地获得,成功或失败,最好直接有接口回调,可以在回调中进行后续逻辑处理
- 当前通信连接的活跃状态需要准确实时而方便地获得,这样有利于重连时对连接的判断
- 能够较为灵活的配置Listener或Handler或Filter
- 支持计数,无论是首次连接失败多次后不再尝试连接,还是中途断开后断线重连多次后不再尝试连接,一般不作无休止地重连
从代码层面看,框架中最好有一个类似Connector的类,能够暴露合适的接口或方法,提供各种状态与回调,使通信连接的动向能够实时把握,然而事情并不是那么美好。
连接结果
由于框架设计的一些原则,一个connector根本不足以暴露这些接口。
对于Mina而言,作为客户端一般用于连接的连接器是NioSocketConnector;
对于Netty而言,则是Bootstrap;
下表是一些常见的定义在两个框架中的对比,不一定准确,但意义相近;
定义 | Mina | Netty |
连接器 | SocketConnector | Bootstrap |
会话 | IoSession | Channel |
连接结果 | ConnectFuture | ChannelFuture |
逻辑处理 | IoHandler | ChannelHandler |
过滤器 | IoFilter | ChannelHandler |
对于Mina而言,连接操作是这样的:
ConnectFuture future = mConnector.connect();
future.awaitUninterruptibly();
if (future.isConnected()) {
//得到会话
mSession = future.getSession();
}
对于Netty来说,连接可以写成与Mina几乎相同的形式:
ChannelFuture future = bootstrap.connect();
future.awaitUninterruptibly();
if(future.isSuccess()){
mChannel = future.channel();
}
也可以不阻塞等待,两种future都可以自行添加Listener监听异步任务是否完成:
//Mina
future.addListener(new IoFutureListener<IoFuture>() {
@Override
public void operationComplete(IoFuture ioFuture) {
}
});
//Netty
future.addListener(new GenericFutureListener<ChannelFuture>() {
@Override
public void operationComplete(ChannelFuture f) throws Exception {
}
});
毕竟是出自一人之手,部分API真是惊人的相似。
到这里,第一个连接返回结果问题算是有所结论,两种框架都可以正常返回连接的结果。
会话状态
而上述代码中,返回的mSession与mChannel就是得到的会话,这两种类各自提供了一些接口,可以用于获得通信连接的实时状态。
Mina的IoSession这里只取部分方法:
public interface IoSession {
IoHandler getHandler();
IoSessionConfig getConfig();
IoFilterChain getFilterChain();
ReadFuture read();
WriteFuture write(Object var1);
WriteFuture write(Object var1, SocketAddress var2);
CloseFuture closeNow();
boolean isConnected();
boolean isActive();
boolean isClosing();
boolean isSecured();
CloseFuture getCloseFuture();
SocketAddress getRemoteAddress();
SocketAddress getLocalAddress();
SocketAddress getServiceAddress();
boolean isIdle(IdleStatus var1);
boolean isReaderIdle();
boolean isWriterIdle();
boolean isBothIdle();
}
再对比看下Netty提供的Channel,这里也只取部分方法展示:
public interface Channel extends AttributeMap, ChannelOutboundInvoker, Comparable<Channel> {
EventLoop eventLoop();
Channel parent();
ChannelConfig config();
boolean isOpen();
boolean isRegistered();
boolean isActive();
SocketAddress localAddress();
SocketAddress remoteAddress();
boolean isWritable();
Channel.Unsafe unsafe();
ChannelPipeline pipeline();
public interface Unsafe {
SocketAddress localAddress();
SocketAddress remoteAddress();
void register(EventLoop var1, ChannelPromise var2);
void bind(SocketAddress var1, ChannelPromise var2);
void connect(SocketAddress var1, SocketAddress var2, ChannelPromise var3);
void disconnect(ChannelPromise var1);
void close(ChannelPromise var1);
void write(Object var1, ChannelPromise var2);
void flush();
}
}
可以看出,无论是IoSession还是Channel,都有相关的API可以知晓通信是否活跃,所以第二个问题在可以获得IoSession或Channel的情况下,是没有问题的。
配置Handler
那么再看配置Listener或Handler的相差操作是否灵活。
二者在这方面的差别较为明显。
对于Mina而言,添加Handler可以直接利用Connector,真正的逻辑Handler只能由setHandler方法添加,且只能为一个,而相关的Filter则要通过getFilterChain()拿到的过滤器集合去添加;对于Mina来说,Handler和Filter是没有交集的,他们分属不同的接口IoHandler和IoFilter:
mConnector.setHandler(handler);
mConnector.getFilterChain().addLast(CODEC, protocolCodecFilter);
Netty有所不同,netty中所有的handler、filter都是ChannelHandller,这些handler都要在连接行为发生后才能生效,也就是挂载到Channel上的,而不是Bootstrap,一般添加是这样的:
bootstrap.handler(handler);
channel.pipeline().addLast(someHandler);
channel.pipeline().addLast(someFilter);
但handler依旧只能添加一个,如果要添加多个handler或filter,就必须获取到channel,然后进行添加,netty本身提供了一个ChannelInitializer可以用于添加多个channelHandler,一般会这么写:
bootstrap.handler(new ChannelInitializer<Channel>() {
@Override
protected void initChannel(Channel channel) throws Exception {
channel.pipeline().addLast(handler);
channel.pipeline().addLast(someHandler);
channel.pipeline().addLast(someFilter);
}
});
对于Netty来说,Handler和Filter是同一个东西,都是ChannelHandler。
两者在这方面的区别比较明显:
一是netty将handler和filter都统一为handler了,
二是netty不能像mina一样,在未连接之前就可以配置所有的Handler或Filter,netty必须获得channel也就是连接成功后才能配置多个Filter。
这就造成了一个问题,Mina可以提前就配置监听器监听连接的状态,可以正常监听中途断开,也就是在创建Connector后就可以挂载上监听:
mConnector.getFilterChain().addFirst("reconnect", new IoFilterAdapter() {
@Override
public void sessionClosed(NextFilter nextFilter, IoSession session) throws Exception {
//监听到断开,可接入回调接口,做进一步的重连逻辑
mConnector.connect();
}
});
而Netty不能,创建Connector也就是Bootstrap并不能实现类似的挂载,Bootstrap只能挂载一个Handler,而相关的过滤器或监听只能在Channel出现后再进行挂载,那么就会写成这样:
bootstrap.handler(new ChannelInitializer<Channel>() {
@Override
protected void initChannel(Channel channel) throws Exception {
//添加其他Filter或Handler
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
super.channelInactive(ctx);
//监听到断开,重连
bootstrap.connect();
}
});
这里initChannel方法永远是最先被调用的,因为在源码中是这样的:
//ChannelInitializer.java
protected abstract void initChannel(C var1) throws Exception;
public final void channelRegistered(ChannelHandlerContext ctx) throws Exception {
if (this.initChannel(ctx)) {
ctx.pipeline().fireChannelRegistered();
this.removeState(ctx);
} else {
ctx.fireChannelRegistered();
}
}
在这种逻辑下,Mina可以在sessionClosed回调中使用SocketConnetor进行重连,Netty可以在channelInactive回调中使用Bootstrap进行重连。
看起来没什么毛病。
但需要注意一点,就是Handler的复用问题,也就是对Handler或Filter的检查,Mina和Netty都有对Handler的重复添加进行过检查,不过检查逻辑有细微的差别。
Mina中是这样检查的:
//DefaultIoFilterChain.java
public synchronized void addLast(String name, IoFilter filter) {
this.checkAddable(name);
this.register(this.tail.prevEntry, name, filter);
}
private final Map<String, Entry> name2entry = new ConcurrentHashMap();
private void checkAddable(String name) {
if (this.name2entry.containsKey(name)) {
throw new IllegalArgumentException("Other filter is using the same name '" + name + "'");
}
}
可以看到,Mina只会检查Filter在Map中对应的key是否被使用过,当然理论上Filter挂载在SocketConnector的FilterChain中,只要配置过一次,就无需再进行配置。
那么Netty呢?
Netty的Handler不是能随意复用的,要复用必须标明注解@Sharable,否则就会出现异常:
警告: Failed to initialize a channel. Closing: [id: 0x1caafa97]
io.netty.channel.ChannelPipelineException: io.netty.handler.timeout.IdleStateHandler is not a @Sharable handler, so can't be added or removed multiple times.
这是因为在源码进行检查时,是对Handler本身进行检查的,handler会有一个added的属性,一旦被添加使用过,就会置为true,而判断逻辑会阻止为added=true的handler添加进来 。这样一来,如果强行添加已经添加过的handler就会抛出异常:
//DefaultChannelPipeline.java
public final ChannelPipeline addLast(EventExecutorGroup group, String name, ChannelHandler handler) {
AbstractChannelHandlerContext newCtx;
synchronized(this) {
checkMultiplicity(handler);
newCtx = this.newContext(group, this.filterName(name, handler), handler);
//省略部分代码
}
this.callHandlerAdded0(newCtx);
return this;
}
private static void checkMultiplicity(ChannelHandler handler) {
if (handler instanceof ChannelHandlerAdapter) {
ChannelHandlerAdapter h = (ChannelHandlerAdapter)handler;
if (!h.isSharable() && h.added) {
throw new ChannelPipelineException(h.getClass().getName() + " is not a @Sharable handler, so can't be added or removed multiple times.");
}
h.added = true;
}
}
这也就说明使用channel.pipeline().addLast(handler)这种方法添加handler时,如果想不同的Channel添加同一个Handler实例,每种handler都必须注解了@Sharable,如果正好要使用IdleStateHandler这种源码内部的Handler,而IdleStateHandler是没有注解过@Sharable,那么就会出现上面的异常。
而实际应用中,为了实现心跳,IdleStateHandler是一般都会使用到的。
那么问题来了,Mina每次重新连接,创建新的session,但只要SocketConnector没有变,所有Handler和Filter自然就没有变,仍然可用,因为所有Handler和Filter是挂载到SocketConnector的FilterChain中,算是只和Connector相关的;
而Netty,如果重新连接的话,会创建新的Channel,然后会重新调用initChannel,然后利用channel.pipeline().addLast添加Handler,算是挂载到Channel上的,而不是Bootstrap上。
这样显示出两者最大的区别就是,Mina中配置一次即可,而Netty则需要每次产生新的Channel时对其进行重新配置。
所以Netty中的handler想复用的话,就必须加注解,否则就会报异常。如果一定要用到无法注解@Sharable的Handler,比如上面的IdleStateHandler,那就要想办法每次initChannel时,也新建一个新的IdleStateHandler…
或者,继承IdleStateHandler,然后加上注解也行,虽然也很丑就是了。
So Bad…
这样的情况下,可以想办法,每次都新建,类似这种:
FunctionsChannelHandler functionsChannelHandler = new FunctionsChannelHandler(bootstrap){
@Override
public ChannelHandler[] handlers() {
return new ChannelHandler[]{
new NormalClientEncoder(),
new IdleStateHandler(20, 10, 20),
this,
new NormalClientHandler()};
}
};
bootstrap.handler(new ChannelInitializer<Channel>() {
@Override
protected void initChannel(Channel channel) throws Exception {
//添加各种handler
channel.pipeline().addLast(functionsChannelHandler.handlers());
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
super.channelInactive(ctx);
//监听到断开
}
});
因为netty把所有监听器过滤器逻辑处理都归为ChannelHandler的原因,把一个handler扩展成一个功能较为丰富的handler是一种不错的方法 。或者沿用这种思路,使其每次新加Handler时,都是new过的Handler。
应对框架自带的一些未注解@Sharable的类,也可以继承之,自行加注解:
@ChannelHandler.Sharable
public class HeartHandler extends IdleStateHandler {
public HeartHandler(int readerIdleTimeSeconds, int writerIdleTimeSeconds, int allIdleTimeSeconds) {
super(readerIdleTimeSeconds, writerIdleTimeSeconds, allIdleTimeSeconds);
}
public HeartHandler(long readerIdleTime, long writerIdleTime, long allIdleTime, TimeUnit unit) {
super(readerIdleTime, writerIdleTime, allIdleTime, unit);
}
public HeartHandler(boolean observeOutput, long readerIdleTime, long writerIdleTime, long allIdleTime, TimeUnit unit) {
super(observeOutput, readerIdleTime, writerIdleTime, allIdleTime, unit);
}
}
这样一来,配置Handler也勉强可算灵活了。
连接计数
对连接计数一般都是开发者编写的逻辑,主要是应对无休止地连接。
主要应用在两种场景:
一是首次连接,如果多次连接不成功,那么停止连接,或者另有逻辑;
二是断线重连,如果多次重连不成功,那么停止连接并销毁,或者另有逻辑。
因为Mina和Netty都是多线程模型的缘故,计数为了求稳可以直接使用Atom类,当然觉得大材小用也可以直接使用普通int值,毕竟理论上两次连接中间应该会有一定延时才对。
应用示例
所以最后,都可以对各自的连接器进行二次封装,然后编写对自己有利的逻辑。
对于Mina,大概可以写成这样:
public class TCPConnector {
private static final int BUFFER_SIZE = 10 * 1024;
private static final long CONNECT_TIMEOUT_MILLIS = 10 * 1000;
private static final int KEEPALIVE_REQUEST_INTERVAL = 10;
private static final int KEEPALIVE_REQUEST_TIMEOUT = 40;
private static final String RECONNECT = "reconnect";
private static final String CODEC = "codec";
private static final String HEARTBEAT = "heartbeat";
private static final String EXECUTOR = "executor";
/**
* 连接器
*/
private SocketConnector mConnector;
/**
* 会话
*/
private IoSession mSession;
/**
* 外用接口
*/
private IConnectorListener connectorListener;
/**
* 连接所在线程
*/
private ExecutorService mExecutor;
/**
* 重连次数
*/
private AtomicInteger recconnectCounter;
/**
* 首次连接次数
*/
private AtomicInteger connectCounter;
private String host;
private int port;
public interface IConnectorListener {
/**
* 连接建立成功
*/
void connectSuccess(IoSession session);
/**
* 连接建立失败
*/
void connectFailed();
/**
* 连接中途断掉时
*/
void sessionClosed(IoSession session);
}
public TCPConnector() {
mConnector = new NioSocketConnector();
recconnectCounter = new AtomicInteger(0);
connectCounter = new AtomicInteger(0);
}
/**
* 设置目标地址与端口
*
* @param host 目标地址
* @param port 目标端口
*/
public void setHostPort(String host, int port) {
L.d("设置地址与端口-" + host + ":" + port);
this.host = host;
this.port = port;
}
public String getHost() {
return this.host;
}
/**
* 在子线程中启用连接
*/
public void connectInThread() {
mExecutor.execute(new Runnable() {
@Override
public void run() {
connect();
}
});
}
/**
* 根据设置的参数连接
*/
private void connect() {
//如果已经连接,则直接【连接成功】
if (mSession == null || !mSession.isConnected()) {
//连接
mConnector.setDefaultRemoteAddress(new InetSocketAddress(host, port));
L.i("连接-->" + host + ":" + port);
ConnectFuture future = mConnector.connect();
//阻塞,等待连接建立响应
future.awaitUninterruptibly(CONNECT_TIMEOUT_MILLIS);
//响应连接成功或失败
if (future.isConnected()) {
//得到会话
mSession = future.getSession();
if (connectorListener != null) {
connectCounter.set(0);
connectorListener.connectSuccess(mSession);
}
} else {
if (connectorListener != null) {
connectCounter.incrementAndGet();
connectorListener.connectFailed();
}
}
} else {
if (connectorListener != null) {
connectCounter.incrementAndGet();
connectorListener.connectSuccess(mSession);
}
}
}
/**
* 重连
*/
private void reconnect() {
if (mConnector == null)
throw new IllegalArgumentException("IoConnector cannot be null");
//如果已经连接,则直接【连接成功】
if (mSession == null || !mSession.isConnected()) {
//连接
ConnectFuture future = mConnector.connect();
//阻塞,等待连接建立响应
future.awaitUninterruptibly();
//响应连接成功或失败
if (future.isConnected()) {
//得到会话
mSession = future.getSession();
}
}
}
/**
* 重连
*
* @param reconnectTimeoutMills 连接的超时时间
* @param reconnectTimes 重连次数
*/
public void reconnect(final long reconnectTimeoutMills, final int reconnectTimes) {
try {
recconnectCounter.set(0);
while (mConnector != null && !(mSession != null && mSession.isConnected()) && recconnectCounter.incrementAndGet() < reconnectTimes) {
reconnect();
if (mSession != null && mSession.isConnected()) {
break;
}else{
TimeUnit.MILLISECONDS.sleep(reconnectTimeoutMills);
}
L.w(Thread.currentThread().getName() + "," + "重连" + host + ":" + port + "(" + recconnectCounter.get() + ")次...");
}
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
if (mSession != null && mSession.isConnected()) {
if (connectorListener != null) {
connectorListener.connectSuccess(mSession);
}
} else {
if (connectorListener != null) {
connectorListener.connectFailed();
}
}
}
}
public IoSession getSession() {
return mSession;
}
public IoConnector getConnector() {
return mConnector;
}
public boolean isActive() {
return mConnector != null && mConnector.isActive() && mSession != null;
}
public boolean isConnected() {
return mSession != null && mSession.isConnected();
}
public IConnectorListener getConnectorListener() {
return connectorListener;
}
public int getRecconnectCounter() {
return recconnectCounter.get();
}
public int getConnectCounter() {
return connectCounter.get();
}
public void resetConnectCounter() {
connectCounter.set(0);
}
/**
* 断开连接,释放资源
*/
public void disconnect() {
if (mConnector != null) {
connectorListener = null;
mConnector.getFilterChain().clear();
mConnector.dispose();
mConnector = null;
}
if (mSession != null) {
mSession.closeNow();
mSession = null;
}
if (mExecutor != null) {
mExecutor.shutdown();
mExecutor = null;
}
L.w("断开");
}
public static class Builder {
private TCPConnector newInstance = new TCPConnector();
private ProtocolCodecFilter protocolCodecFilter;
private KeepAliveFilter keepAliveFilter;
public Builder setExecutor(ExecutorService executor) {
newInstance.mExecutor = executor;
return this;
}
public Builder setConnectListener(IConnectorListener listener) {
newInstance.connectorListener = listener;
return this;
}
public Builder setHost(String host) {
newInstance.host = host;
return this;
}
public Builder setPort(int port) {
newInstance.port = port;
return this;
}
public Builder setProtocolCodecFilter(ProtocolCodecFactory protocolCodecFactory) {
protocolCodecFilter = new ProtocolCodecFilter(protocolCodecFactory);
return this;
}
public Builder setConnectTimeoutMillis(long connectTimeoutMillis) {
newInstance.mConnector.setConnectTimeoutMillis(connectTimeoutMillis);
return this;
}
public Builder setKeepAliveFilter(KeepAliveMessageFactory keepAliveMessageFactory, int keepAliveRequestInterval) {
keepAliveFilter = new KeepAliveFilter(keepAliveMessageFactory, IdleStatus.BOTH_IDLE, KeepAliveRequestTimeoutHandler.LOG, keepAliveRequestInterval, KEEPALIVE_REQUEST_TIMEOUT);
return this;
}
public Builder setKeepAliveFilter(KeepAliveMessageFactory keepAliveMessageFactory, KeepAliveRequestTimeoutHandler keepAliveRequestTimeoutHandler, int keepAliveRequestInterval, int keepAliveRequestTimeOut) {
keepAliveFilter = new KeepAliveFilter(keepAliveMessageFactory, IdleStatus.BOTH_IDLE, keepAliveRequestTimeoutHandler, keepAliveRequestInterval, keepAliveRequestTimeOut);
return this;
}
public Builder setHandlerAdapter(IoHandlerAdapter handler) {
newInstance.mConnector.setHandler(handler);
return this;
}
public Builder setReadBuffer(int size) {
newInstance.mConnector.getSessionConfig().setReadBufferSize(size);
return this;
}
public Builder setReceiveBuffer(int size) {
newInstance.mConnector.getSessionConfig().setReceiveBufferSize(size);
return this;
}
public Builder setSendBuffer(int size) {
newInstance.mConnector.getSessionConfig().setSendBufferSize(size);
return this;
}
public TCPConnector build() {
//添加重连监听
if (newInstance.connectorListener != null) {
newInstance.mConnector.getFilterChain().addFirst(RECONNECT, new IoFilterAdapter() {
@Override
public void sessionClosed(NextFilter nextFilter, IoSession session) throws Exception {
if (newInstance != null && newInstance.connectorListener != null)
newInstance.connectorListener.sessionClosed(session);
}
});
}
//设置编码解码
if (protocolCodecFilter != null)
newInstance.mConnector.getFilterChain().addLast(CODEC, protocolCodecFilter);
//设置心跳
if (keepAliveFilter != null)
newInstance.mConnector.getFilterChain().addLast(HEARTBEAT, keepAliveFilter);
//connector不允许使用OrderedThreadPoolExecutor
newInstance.mConnector.getFilterChain().addLast(EXECUTOR, new ExecutorFilter(Executors.newSingleThreadExecutor()));
return newInstance;
}
}
@Override
public String toString() {
return "MinaHelper{" +
"mSession=" + mSession +
", mConnector=" + mConnector +
", connectorListener=" + connectorListener +
", mExecutor=" + mExecutor +
'}';
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
TCPConnector connector = (TCPConnector) o;
return port == connector.port && (host != null ? host.equals(connector.host) : connector.host == null);
}
@Override
public int hashCode() {
int result = host != null ? host.hashCode() : 0;
result = 31 * result + port;
return result;
}
使用起来是这样的:
HigherGateWayHandler higherGateWayHandler = new HigherGateWayHandler();
TCPConnector higherGateWayClient = new TCPConnector.Builder()
.setExecutor(ThreadPool.singleThread("higher_gateway_client"))
.setHost(NC.GATEWAT_HIGHER_HOST)
.setPort(NC.LOWER_PORT)
.setConnectTimeoutMillis(10 * 1000)
.setReadBuffer(10 * 1024)
.setHandlerAdapter(higherGateWayHandler)
.setProtocolCodecFilter(new HigherGateWayCodecFactory())
.setKeepAliveFilter(new KeepAliveHigherGateWay(), higherGateWayHandler, 10, 20)
.setConnectListener(new TCPConnector.IConnectorListener() {
@Override
public void connectSuccess(IoSession session) {
//连接成功后
}
@Override
public void connectFailed() {
//重连失败
if (higherGateWayClient.getRecconnectCounter() == 3) {
//重连失败后
}
//非重连失败,优先级连接情况下
if (higherGateWayClient.getRecconnectCounter() == 0 && higherGateWayClient.getConnectCounter() > 2) {
higherGateWayClient.resetConnectCounter();
} else {
higherGateWayClient.connectInThread();
}
}
@Override
public void sessionClosed(IoSession session) {
executors.execute(new Runnable() {
@Override
public void run() {
//重连逻辑
higherGateWayClient.reconnect(10 * 1000, 3);
}
});
}
})
.build();
而Netty,封装起来会有一点花里胡哨,目前遇到的问题是当重连以后复用IdleStateHandler这种Handler时,就会使得其中的计时机制失效,也就是说,心跳没用了,暂时不明原因,大概率是其中的线程被销毁无法再起的原因。那么当前就只能想办法每次调用initChannel时,创建新的Handler才行:
public class NettyConnector {
/**
* 连接器
*/
private Bootstrap bootstrap;
/**
* 地址
*/
private String host;
private int port;
/**
* 会话
*/
private Channel channel;
private static final long TIME_OUT = 10;
private long connectTimeoutMills;
/**
* 重连次数
*/
private AtomicInteger recconnectCounter;
/**
* 首次连接次数
*/
private AtomicInteger connectCounter;
/**
* 以接口引出通信状态
*/
public interface IChannelStateListener {
void onConnectSuccess(Channel channel);
void onConnectFailed();
void onDisconnect();
}
private IChannelStateListener channelStateListener;
private NettyConnector(final Builder builder) {
recconnectCounter = new AtomicInteger(0);
connectCounter = new AtomicInteger(0);
connectTimeoutMills = builder.timeoutMills;
bootstrap = builder.bootstrap;
bootstrap.handler(new ChannelInitializer() {
@Override
protected void initChannel(Channel channel) throws Exception {
channel.pipeline().addLast(new ChannelDisconnectHandler());
channel.pipeline().addLast(builder.handlerSet.handlers());
}
});
}
public void setRemoteAddress(String host, int port) {
L.d("设置地址与端口-" + host + ":" + port);
this.host = host;
this.port = port;
}
public void setChannelStateListener(IChannelStateListener listener) {
channelStateListener = listener;
}
public void connect() {
if (channel == null || !channel.isActive()) {
bootstrap.remoteAddress(this.host, this.port);
L.d("第" + (connectCounter.get() + 1) + "次连接" + host + ":" + port + "中......");
final long startMills = System.currentTimeMillis();
ChannelFuture channelFuture = bootstrap.connect();
channelFuture.addListener(new GenericFutureListener<ChannelFuture>() {
@Override
public void operationComplete(ChannelFuture f) throws Exception {
if (f.isSuccess()) {
L.d("连接(" + bootstrap.config().remoteAddress() + ")成功");
channel = f.channel();
if (channelStateListener != null) {
connectCounter.set(0);
channelStateListener.onConnectSuccess(channel);
}
} else {
long delay = System.currentTimeMillis() - startMills;
if (delay > 0) {
TimeUnit.MILLISECONDS.sleep(connectTimeoutMills - delay);
}
L.d("连接(" + bootstrap.config().remoteAddress() + ")失败");
if (channelStateListener != null) {
connectCounter.incrementAndGet();
channelStateListener.onConnectFailed();
}
}
}
});
}
}
private void reconnect() {
if (bootstrap == null)
throw new IllegalArgumentException("bootstrap cannot be null");
//如果已经连接,则直接【连接成功】
if (channel == null || !channel.isActive()) {
//连接
channel = bootstrap.connect().awaitUninterruptibly().channel();
}
}
/**
* 重连
* @param reconnectTimeoutMills 重连超时时间
* @param reconnectTimes 重连次数
*/
public void reconnect(final long reconnectTimeoutMills, final int reconnectTimes) {
try {
recconnectCounter.set(0);
while (channel != null && !channel.isActive() && recconnectCounter.getAndIncrement() < reconnectTimes) {
L.d(Thread.currentThread().getName() + "," + "重连" + bootstrap.config().remoteAddress() + "(" + recconnectCounter.get() + ")次...");
reconnect();
if (channel.isActive()) {
break;
} else {
TimeUnit.MILLISECONDS.sleep(reconnectTimeoutMills);
}
L.d(channel.isActive() + "");
}
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
if (channel != null && channel.isActive()) {
if (channelStateListener != null) {
channelStateListener.onConnectSuccess(channel);
}
} else {
if (channelStateListener != null) {
channelStateListener.onConnectFailed();
}
}
}
}
public Channel getChannel() {
return channel;
}
public boolean isConnected() {
return channel != null && channel.isActive();
}
public String getAddress() {
return host + ":" + port;
}
public int getConnectFailedTimes() {
return connectCounter.get();
}
public int getReconnectFailedTimes() {
return recconnectCounter.get();
}
public static class Builder {
private Bootstrap bootstrap = new Bootstrap();
private HandlerSet handlerSet;
private long timeoutMills = 10 * 1000;
public Builder group(EventLoopGroup loopGroup) {
bootstrap.group(loopGroup);
return this;
}
@Deprecated
public Builder remoteAddress(String inetHost, int inetPort) {
bootstrap.remoteAddress(inetHost, inetPort);
return this;
}
public Builder setConnectTimeoutMills(long timeout) {
timeoutMills = timeout;
return this;
}
public Builder handler(HandlerSet handlers) {
handlerSet = handlers;
return this;
}
public NettyConnector build() {
bootstrap.channel(NioSocketChannel.class);
return new NettyConnector(this);
}
}
/**
* 主要用于监听断开
*/
class ChannelDisconnectHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
ctx.fireChannelInactive();
if (channelStateListener != null) {
channelStateListener.onDisconnect();
}
}
}
/**
* 主要用于创建新的handler,避免复用带来的一些问题
*/
@ChannelHandler.Sharable
public static abstract class HandlerSet extends ChannelInboundHandlerAdapter {
public abstract ChannelHandler[] handlers();
}
}
因为Netty不能像Mina直接在Connector上挂载监听sessionClosed,只能用一个ChannelDisconnectHandler这样的东西去监听是否已经断开,并通过接口引出结果;
并且因为只能在Channel.Pipeline中才能添加多个Handler的原因,这里用一个HandlerSet强行将所有需要的Handler集合,然后在创建Bootstrap的时候一次性添加进去,想要保证每次都新建,这里就使用抽象方法,让使用的时候可以自行创建。
注意,由于这里的抽象类HandlerSet每次其实并不是新建的,所有是需要复用的,所以需要加注解@Sharable,但也只需要加它一个就行了,其他都是新建出来的,无需理会。
写出来就是这样:
NettyConnector connector = new NettyConnector.Builder()
.group(new NioEventLoopGroup())
.handler(new NettyConnector.HandlerSet() {
@Override
public ChannelHandler[] handlers() {
return new ChannelHandler[]{new HeartHandler(10, 10, 10),
new NormalClientEncoder(),
new NormalClientHeartBeatHandler(),
new NormalClientHandler()};
}
})
.setConnectTimeoutMills(5 * 1000)
.build();
connector.setRemoteAddress("192.168.0.102", 8000);
connector.setChannelStateListener(new NettyConnector.IChannelStateListener() {
@Override
public void onConnectSuccess(Channel channel) {
L.d("连接" + channel.remoteAddress().toString() + "成功");
}
@Override
public void onConnectFailed() {
L.d("连接" + connector.getAddress() + "失败");
if (connector.getReconnectFailedTimes() == 0 && connector.getConnectFailedTimes() < 3) {
connector.connect();
}
}
@Override
public void onDisconnect() {
L.d(connector.getChannel().remoteAddress().toString() + "已断开");
connector.reconnect(5000, 5);
}
});
其中的HeartHandler是继承自IdleStateHandler的。
整个封装显得花里胡哨…却又很丑,不过勉强能用,水平有限。
就这样吧。