netty中提供了 tcp-keepalive 的设置:
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(bossGroup,workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG,128)
.childOption(ChannelOption.SO_KEEPALIVE,true)//这个地方
设置:ChannelOption.SO_KEEPALIVE, true 表示打开 TCP 的 keepAlive 设置。
一个 Netty 服务端可能会面临上万个连接,如何去维护这些连接是应用应该去处理的事情。在 Netty 中提供了 IdleStateHandler 类专门用于处理心跳。
IdleStateHandler 的构造函数如下:
public IdleStateHandler(long readerIdleTime,
long writerIdleTime, long allIdleTime,TimeUnit unit){
}
long readerIdleTime, long writerIdleTime, long allIdleTime
- readerIdleTime 表示多长时间没有读,就会发送心跳检测包,检测是否还是连接状态
- writerIdleTime 表示多长时间没有写,就会发送心跳检测包,检测是否还是连接状态
- allIdleTime 表示多长时间没有读写,就会发送心跳检测包,检测是否还是连接状态
- unit 代表时间单位
示例代码:
Server
package org.joisen.netty.heartbeat;
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;
import java.util.concurrent.TimeUnit;
public class MyServer {
public static void main(String[] args) throws InterruptedException {
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossGroup,workerGroup)
.channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO)) //在bossGroup增加一个日志处理器
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//加入一个netty提供的IdleStateHandler
pipeline.addLast(new IdleStateHandler(3,5,7, TimeUnit.SECONDS));
//加入一个对空闲检测进一步处理的handler(自定义)
pipeline.addLast(new MyServerHandler());
}
});
//启动服务器
ChannelFuture channelFuture = serverBootstrap.bind(7000).sync();
channelFuture.channel().closeFuture().sync();
}finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
Handler
package org.joisen.netty.heartbeat;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
public class MyServerHandler extends ChannelInboundHandlerAdapter {
/**
* @param ctx 上下文
* @param evt 事件
* @throws Exception
*/
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
if(evt instanceof IdleStateEvent){
//将 evt 向下转型 IdleStateEvent
IdleStateEvent 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() + "--超时时间--"+eventType);
System.out.println("服务器做相应处理");
}
}
}
Client 用的是之前写的,反正端口一样,可以用于测试
package org.joisen.netty.groupchat;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import java.util.Scanner;
public class GroupChatClient {
private final String host;
private final int port;
public GroupChatClient(String host,int port){
this.host = host;
this.port = port;
}
public void run() throws Exception{
NioEventLoopGroup eventExecutors = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(eventExecutors)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
//得到pipeline
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast("decoder",new StringDecoder());
pipeline.addLast("encoder",new StringEncoder());
}
});
ChannelFuture channelFuture = bootstrap.connect(host, port).sync();
//提示
Channel channel = channelFuture.channel();
System.out.println("------------"+channel.localAddress()+"----------");
//客户端需要输入信息,创建一个扫描器
Scanner scanner = new Scanner(System.in);
while(scanner.hasNextLine()){
String msg = scanner.nextLine();
//通过channel发送到服务器
channel.writeAndFlush(msg+"\r\n");
}
}finally {
eventExecutors.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new GroupChatClient("127.0.0.1",7000).run();
}
}
运行MyServer.class;
运行Client.class
运行结果:
二月 03, 2021 8:41:47 下午 io.netty.handler.logging.LoggingHandler channelRegistered
信息: [id: 0xcd351bad] REGISTERED
二月 03, 2021 8:41:47 下午 io.netty.handler.logging.LoggingHandler bind
信息: [id: 0xcd351bad] BIND: 0.0.0.0/0.0.0.0:7000
二月 03, 2021 8:41:47 下午 io.netty.handler.logging.LoggingHandler channelActive
信息: [id: 0xcd351bad, L:/0:0:0:0:0:0:0:0:7000] ACTIVE
二月 03, 2021 8:41:50 下午 io.netty.handler.logging.LoggingHandler channelRead
信息: [id: 0xcd351bad, L:/0:0:0:0:0:0:0:0:7000] READ: [id: 0xa83f59af, L:/127.0.0.1:7000 - R:/127.0.0.1:57305]
二月 03, 2021 8:41:50 下午 io.netty.handler.logging.LoggingHandler channelReadComplete
信息: [id: 0xcd351bad, L:/0:0:0:0:0:0:0:0:7000] READ COMPLETE
二月 03, 2021 8:42:21 下午 io.netty.handler.logging.LoggingHandler channelRead
信息: [id: 0xcd351bad, L:/0:0:0:0:0:0:0:0:7000] READ: [id: 0x3ded73b3, L:/127.0.0.1:7000 - R:/127.0.0.1:57348]
二月 03, 2021 8:42:21 下午 io.netty.handler.logging.LoggingHandler channelReadComplete
信息: [id: 0xcd351bad, L:/0:0:0:0:0:0:0:0:7000] READ COMPLETE
二月 03, 2021 8:42:52 下午 io.netty.handler.logging.LoggingHandler channelRead
信息: [id: 0xcd351bad, L:/0:0:0:0:0:0:0:0:7000] READ: [id: 0x6f9f5a19, L:/127.0.0.1:7000 - R:/127.0.0.1:57391]
二月 03, 2021 8:42:52 下午 io.netty.handler.logging.LoggingHandler channelReadComplete
信息: [id: 0xcd351bad, L:/0:0:0:0:0:0:0:0:7000] READ COMPLETE
/127.0.0.1:57391--超时时间--读空闲
服务器做相应处理
/127.0.0.1:57391--超时时间--写空闲
服务器做相应处理
/127.0.0.1:57391--超时时间--读空闲
服务器做相应处理
/127.0.0.1:57391--超时时间--读写空闲
服务器做相应处理
/127.0.0.1:57391--超时时间--读空闲
服务器做相应处理
/127.0.0.1:57391--超时时间--写空闲
服务器做相应处理
/127.0.0.1:57391--超时时间--读空闲
服务器做相应处理
/127.0.0.1:57391--超时时间--读写空闲
服务器做相应处理
/127.0.0.1:57391--超时时间--写空闲
服务器做相应处理
以上简单了演示了一下,netty的心跳机制,其实主要就是使用了IdleStateHandler。创作不易 给个三连吧~