Java基础之《netty（20）—netty心跳机制》

一、实例要求

1、编写一个netty心跳检测机制案例，当服务器超过3秒没有读时，就提示读空闲
2、当服务器超过5秒没有写操作时，就提示写空闲
3、当服务器超过7秒没有读或者写操作时，就提示读写空闲

二、服务端

1、MyServer.java

package netty.heartbeat;import java.util.concurrent.TimeUnit;import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.timeout.IdleStateHandler;public class MyServer {public static void main(String[] args) {//创建两个线程组EventLoopGroup bossGroup = new NioEventLoopGroup(1);EventLoopGroup workerGroup = new NioEventLoopGroup(); //默认cpu核数*2try {ServerBootstrap server = new ServerBootstrap();server.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)//在boosGroup增加一个日志处理器.handler(new LoggingHandler(LogLevel.INFO)).childHandler(new ChannelInitializer() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ChannelPipeline pipeline = ch.pipeline();//加入一个netty提供的IdleStateHandler/*** 说明* 1. IdleStateHandler是netty提供的处理空闲状态的处理器* 2. public IdleStateHandler(long readerIdleTime, long writerIdleTime, long allIdleTime, TimeUnit unit)* 3. 参数* long readerIdleTime：表示多长时间没有读了，就会发送一个心跳检测包，检测是否还是连接的状态* long writerIdleTime：表示多长时间没有写了，也会发送一个心跳检测包* long allIdleTime：表示多长时间既没有读也没有写了，也会发送一个心跳检测包* 4. 文档说明* Triggers an {@link IdleStateEvent} when a {@link Channel} has not performed read, write, or both operation for a while.* 5. 当IdleStateEvent触发后，就会传递给管道的下一个handler* 6. 通过调用（触发）下一个handler的userEventTriggered，在该方法中去处理IdleStateEvent事件* */pipeline.addLast(new IdleStateHandler(3, 5, 7, TimeUnit.SECONDS));//加入一个对空闲检测进一步处理的自定义handlerpipeline.addLast(new MyServerHandler());}});//启动服务器ChannelFuture cf = server.bind(7000).sync();cf.channel().closeFuture().sync();} catch (Exception e) {e.printStackTrace();} finally {bossGroup.shutdownGracefully();workerGroup.shutdownGracefully();}}
}

2、MyServerHandler.java

package netty.heartbeat;import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.timeout.IdleStateEvent;public class MyServerHandler extends ChannelInboundHandlerAdapter {/*** ctx：上下文* evt：事件*/@Overridepublic void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {if (evt instanceof IdleStateEvent) {//将evt向下转型 IdleStateEventIdleStateEvent event = (IdleStateEvent) evt;String eventType = null;switch (event.state()) {case READER_IDLE:eventType = "读空闲";break;case WRITER_IDLE:eventType = "写空闲";break;case ALL_IDLE:eventType = "读写空闲";break;}System.out.println(ctx.channel().remoteAddress() + "超时事件：" + eventType);System.out.println("服务器做相应的处理......");}}
}

三、测试

用群聊的客户端连接即可。

15:17:11.383 [main] DEBUG io.netty.util.internal.logging.InternalLoggerFactory - Using SLF4J as the default logging framework
15:17:11.393 [main] DEBUG io.netty.channel.MultithreadEventLoopGroup - -Dio.netty.eventLoopThreads: 16
15:17:11.424 [main] DEBUG io.netty.util.internal.InternalThreadLocalMap - -Dio.netty.threadLocalMap.stringBuilder.initialSize: 1024
15:17:11.425 [main] DEBUG io.netty.util.internal.InternalThreadLocalMap - -Dio.netty.threadLocalMap.stringBuilder.maxSize: 4096
15:17:11.442 [main] DEBUG io.netty.channel.nio.NioEventLoop - -Dio.netty.noKeySetOptimization: false
15:17:11.442 [main] DEBUG io.netty.channel.nio.NioEventLoop - -Dio.netty.selectorAutoRebuildThreshold: 512
15:17:11.472 [main] DEBUG io.netty.util.internal.PlatformDependent - Platform: Windows
15:17:11.476 [main] DEBUG io.netty.util.internal.PlatformDependent0 - -Dio.netty.noUnsafe: false
15:17:11.476 [main] DEBUG io.netty.util.internal.PlatformDependent0 - Java version: 8
15:17:11.479 [main] DEBUG io.netty.util.internal.PlatformDependent0 - sun.misc.Unsafe.theUnsafe: available
15:17:11.480 [main] DEBUG io.netty.util.internal.PlatformDependent0 - sun.misc.Unsafe.copyMemory: available
15:17:11.480 [main] DEBUG io.netty.util.internal.PlatformDependent0 - java.nio.Buffer.address: available
15:17:11.481 [main] DEBUG io.netty.util.internal.PlatformDependent0 - direct buffer constructor: available
15:17:11.483 [main] DEBUG io.netty.util.internal.PlatformDependent0 - java.nio.Bits.unaligned: available, true
15:17:11.483 [main] DEBUG io.netty.util.internal.PlatformDependent0 - jdk.internal.misc.Unsafe.allocateUninitializedArray(int): unavailable prior to Java9
15:17:11.483 [main] DEBUG io.netty.util.internal.PlatformDependent0 - java.nio.DirectByteBuffer.(long, int): available
15:17:11.483 [main] DEBUG io.netty.util.internal.PlatformDependent - sun.misc.Unsafe: available
15:17:11.485 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.tmpdir: C:\Users\sjcui\AppData\Local\Temp (java.io.tmpdir)
15:17:11.485 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.bitMode: 64 (sun.arch.data.model)
15:17:11.487 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.maxDirectMemory: 3767533568 bytes
15:17:11.487 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.uninitializedArrayAllocationThreshold: -1
15:17:11.489 [main] DEBUG io.netty.util.internal.CleanerJava6 - java.nio.ByteBuffer.cleaner(): available
15:17:11.490 [main] DEBUG io.netty.util.internal.PlatformDependent - -Dio.netty.noPreferDirect: false
15:17:11.505 [main] DEBUG io.netty.util.internal.PlatformDependent - org.jctools-core.MpscChunkedArrayQueue: available
15:17:12.008 [main] DEBUG io.netty.channel.DefaultChannelId - -Dio.netty.processId: 7028 (auto-detected)
15:17:12.010 [main] DEBUG io.netty.util.NetUtil - -Djava.net.preferIPv4Stack: false
15:17:12.010 [main] DEBUG io.netty.util.NetUtil - -Djava.net.preferIPv6Addresses: false
15:17:12.396 [main] DEBUG io.netty.util.NetUtil - Loopback interface: lo (Software Loopback Interface 1, 127.0.0.1)
15:17:12.397 [main] DEBUG io.netty.util.NetUtil - Failed to get SOMAXCONN from sysctl and file \proc\sys\net\core\somaxconn. Default: 200
15:17:12.780 [main] DEBUG io.netty.channel.DefaultChannelId - -Dio.netty.machineId: 00:50:56:ff:fe:c0:00:01 (auto-detected)
15:17:12.794 [main] DEBUG io.netty.util.ResourceLeakDetector - -Dio.netty.leakDetection.level: simple
15:17:12.794 [main] DEBUG io.netty.util.ResourceLeakDetector - -Dio.netty.leakDetection.targetRecords: 4
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.numHeapArenas: 16
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.numDirectArenas: 16
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.pageSize: 8192
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.maxOrder: 11
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.chunkSize: 16777216
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.tinyCacheSize: 512
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.smallCacheSize: 256
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.normalCacheSize: 64
15:17:12.826 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.maxCachedBufferCapacity: 32768
15:17:12.827 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.cacheTrimInterval: 8192
15:17:12.827 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.cacheTrimIntervalMillis: 0
15:17:12.827 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.useCacheForAllThreads: true
15:17:12.827 [main] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.maxCachedByteBuffersPerChunk: 1023
15:17:12.839 [main] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.allocator.type: pooled
15:17:12.839 [main] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.threadLocalDirectBufferSize: 0
15:17:12.839 [main] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.maxThreadLocalCharBufferSize: 16384
15:17:12.871 [nioEventLoopGroup-2-1] INFO io.netty.handler.logging.LoggingHandler - [id: 0x2865274b] REGISTERED
15:17:12.875 [nioEventLoopGroup-2-1] INFO io.netty.handler.logging.LoggingHandler - [id: 0x2865274b] BIND: 0.0.0.0/0.0.0.0:7000
15:17:12.879 [nioEventLoopGroup-2-1] INFO io.netty.handler.logging.LoggingHandler - [id: 0x2865274b, L:/0:0:0:0:0:0:0:0:7000] ACTIVE
15:23:48.925 [nioEventLoopGroup-2-1] INFO io.netty.handler.logging.LoggingHandler - [id: 0x2865274b, L:/0:0:0:0:0:0:0:0:7000] READ: [id: 0xbccd3289, L:/127.0.0.1:7000 - R:/127.0.0.1:51818]
15:23:48.927 [nioEventLoopGroup-2-1] INFO io.netty.handler.logging.LoggingHandler - [id: 0x2865274b, L:/0:0:0:0:0:0:0:0:7000] READ COMPLETE
/127.0.0.1:51818超时事件：读空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：写空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读写空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：写空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读写空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：写空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：写空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读写空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：读空闲
服务器做相应的处理......
/127.0.0.1:51818超时事件：写空闲
服务器做相应的处理......
15:24:15.372 [nioEventLoopGroup-3-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.maxCapacityPerThread: 4096
15:24:15.373 [nioEventLoopGroup-3-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.maxSharedCapacityFactor: 2
15:24:15.373 [nioEventLoopGroup-3-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.linkCapacity: 16
15:24:15.373 [nioEventLoopGroup-3-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.ratio: 8
15:24:15.382 [nioEventLoopGroup-3-1] DEBUG io.netty.buffer.AbstractByteBuf - -Dio.netty.buffer.checkAccessible: true
15:24:15.382 [nioEventLoopGroup-3-1] DEBUG io.netty.buffer.AbstractByteBuf - -Dio.netty.buffer.checkBounds: true
15:24:15.384 [nioEventLoopGroup-3-1] DEBUG io.netty.util.ResourceLeakDetectorFactory - Loaded default ResourceLeakDetector: io.netty.util.ResourceLeakDetector@50d10e68
15:24:15.390 [nioEventLoopGroup-3-1] WARN io.netty.channel.DefaultChannelPipeline - An exceptionCaught() event was fired, and it reached at the tail of the pipeline. It usually means the last handler in the pipeline did not handle the exception.
java.io.IOException: 远程主机强迫关闭了一个现有的连接。at sun.nio.ch.SocketDispatcher.read0(Native Method)at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:43)at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)at sun.nio.ch.IOUtil.read(IOUtil.java:192)at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:378)at io.netty.buffer.PooledByteBuf.setBytes(PooledByteBuf.java:247)at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1140)at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:347)at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:148)at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:697)at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:632)at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:549)at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:511)at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:918)at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)at java.lang.Thread.run(Thread.java:748)


四、要点

1、netty日志处理器
LoggingHandler(LogLevel.INFO)

2、netty空闲检测处理器
IdleStateHandler

3、说明
1） IdleStateHandler是netty提供的处理空闲状态的处理器
2） public IdleStateHandler(long readerIdleTime, long writerIdleTime, long allIdleTime, TimeUnit unit)
3） 参数
long readerIdleTime：表示多长时间没有读了，就会发送一个心跳检测包，检测是否还是连接的状态
long writerIdleTime：表示多长时间没有写了，也会发送一个心跳检测包
long allIdleTime：表示多长时间既没有读也没有写了，也会发送一个心跳检测包
4） 文档说明
Triggers an {@link IdleStateEvent} when a {@link Channel} has not performed read, write, or both operation for a while.
5） 当IdleStateEvent触发后，就会传递给管道的下一个handler
6） 通过调用（触发）下一个handler的userEventTriggered，在该方法中去处理IdleStateEvent事件