1、Netty的心跳,不像Mina,Mina有个心跳基类,而Netty没有,Netty的心跳也是继承ChannelInboundHandlerAdapter重写channelRead;
以下代码实现:服务端30读空闲,则给客户端发送‘+’,客户端收到后,回'-',如果服务端连续发送3次还是未收到‘-’,则断开连接
TcpServerInitializer 中主要看:
.addLast("ping", new IdleStateHandler(NettyConstants.READERIDLE_TIMESECONDS, 0, 0, TimeUnit.SECONDS))
.addLast("heartbeatHandler", new HeartbeatHandler_Read())
package com.sintech.initializer;
import java.util.concurrent.TimeUnit;
import com.sintech.handler.TcpInHandler;
import com.sintech.handler.TcpOutHandler;
import com.sintech.handler.keepalive.HeartbeatHandler_Read;
import com.sintech.message.codec.MessageDecoder;
import com.sintech.message.codec.MessageEncoder;
import com.sintech.utils.NettyConstants;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.timeout.IdleStateHandler;
import io.netty.util.CharsetUtil;
public class TcpServerInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline()
//.addLast("decoder", new ObjectDecoder(ClassResolvers.cacheDisabled(this.getClass().getClassLoader())))
.addLast(new LoggingHandler(LogLevel.DEBUG))
// 30秒idle,如果连续3次idle,则断开连接
.addLast("ping", new IdleStateHandler(NettyConstants.READERIDLE_TIMESECONDS, 0, 0, TimeUnit.SECONDS))
.addLast("heartbeatHandler", new HeartbeatHandler_Read())
// .addLast(new StringEncoder(CharsetUtil.UTF_8))
// .addLast(new StringDecoder(CharsetUtil.UTF_8))
.addLast(new MessageDecoder())
.addLast(new MessageEncoder())
.addLast("inHandler", new TcpInHandler())
.addLast("outHandler", new TcpOutHandler())
;
}
}
package com.sintech.handler.keepalive;
import com.sintech.utils.NettyConstants;
import com.sintech.utils.NettyLogger;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.socket.DatagramPacket;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
@Sharable
public class HeartbeatHandler_Read extends ChannelInboundHandlerAdapter {
// 心跳失败计数器:未收到client端发送的ping请求
private int unRecPingTimes = 0 ;
// 定义服务端没有收到心跳消息的最大次数
private static final int MAX_UN_REC_PING_TIMES = 3;
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
unRecPingTimes = 0;
if(msg instanceof ByteBuf) {
ByteBuf bb = (ByteBuf)msg;
if(bb.readableBytes() == 1 && bb.getByte(0) == NettyConstants.PING) {
ByteBuf b = ctx.alloc().buffer(1);
// b.writeBytes(NettyConstants.PONG);
b.writeByte(NettyConstants.PONG);
ctx.writeAndFlush(b);
bb.release();
} else {
super.channelRead(ctx, msg);
}
} else if (msg instanceof DatagramPacket) {
DatagramPacket dp = (DatagramPacket) msg;
ByteBuf bb = (ByteBuf) dp.copy().content();
if(bb.readableBytes() == 1 && bb.getByte(0) == NettyConstants.PING) {
ByteBuf b = ctx.alloc().buffer(1);
// b.writeBytes(PONG);
b.writeByte(NettyConstants.PONG);
DatagramPacket dp2 = new DatagramPacket(b, dp.sender());
ctx.writeAndFlush(dp2);
dp.release();
} else {
super.channelRead(ctx, msg);
}
} else {
super.channelRead(ctx, msg);
}
}
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt)
throws Exception {
if (evt instanceof IdleStateEvent) {
IdleState state = ((IdleStateEvent) evt).state();
if (state == IdleState.READER_IDLE) {
unRecPingTimes++;
NettyLogger.getInstance().logInfo("第" + unRecPingTimes + "次IDLE", null);
if(unRecPingTimes >= MAX_UN_REC_PING_TIMES) {
ctx.close();
}
}
} else {
super.userEventTriggered(ctx, evt);
}
}
}