Netty自动重连机制本博客 猫叔的博客，转载请申明出处
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适读人群：Java-Netty 初级
版本：netty 4.1.*
申明：本文旨在重新分享讨论Netty官方相关案例，添加部分个人理解与要点解析。
这个是InChat的案例地址，里面补充了详细的注释，比起官方会容易看一点。
官方案例地址：https://netty.io/4.1/xref/io/netty/example/uptime/package-summary.html
正文- UptimeClient（客户端）
- UptimeClientHandler
- UptimeServer（服务端）
- UptimeServerHandler
- IdleStateHandler https://netty.io/4.1/api/io/netty/handler/timeout/IdleStateHandler.html
一个对Channel尚未执行读、写或两次操作的触发器
| 属性 | 含义 |
|---|---|
| readerIdleTime | 在IdleStateEvent其状态IdleState.READER_IDLE 时的指定时间段没有执行读操作将被触发。指定0禁用。 |
| writerIdleTime | 在IdleStateEvent其状态IdleState.WRITER_IDLE 时的指定时间段没有执行写操作将被触发。指定0禁用。 |
| allIdleTime | 一个IdleStateEvent其状态IdleState.ALL_IDLE 时的时间在规定的时间进行读取和写入都将被触发。指定0禁用。 |
如下一个在没有信息时发送ping消息，且30秒没有入站信息则关闭连接
public class MyChannelInitializer extends ChannelInitializer {
@Override
public void initChannel(Channel channel) {
channel.pipeline().addLast("idleStateHandler", new IdleStateHandler(60, 30, 0));
channel.pipeline().addLast("myHandler", new MyHandler());
}
}
// Handler should handle the IdleStateEvent triggered by IdleStateHandler.
public class MyHandler extends ChannelDuplexHandler {
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
if (evt instanceof IdleStateEvent) {
IdleStateEvent e = (IdleStateEvent) evt;
if (e.state() == IdleState.READER_IDLE) {
ctx.close();
} else if (e.state() == IdleState.WRITER_IDLE) {
ctx.writeAndFlush(new PingMessage());
}
}
}
}
- UptimeClient
public final class UptimeClient {
static final String HOST = System.getProperty("host", "127.0.0.1");
static final int PORT = Integer.parseInt(System.getProperty("port", "8080"));
// 重新连接前睡眠5秒
static final int RECONNECT_DELAY = Integer.parseInt(System.getProperty("reconnectDelay", "5"));
// 当服务器在 10 秒内不发送任何内容时重新连接。
private static final int READ_TIMEOUT = Integer.parseInt(System.getProperty("readTimeout", "10"));
private static final UptimeClientHandler handler = new UptimeClientHandler();
private static final Bootstrap bs = new Bootstrap();
public static void main(String[] args) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
bs.group(group)
.channel(NioSocketChannel.class)
.remoteAddress(HOST,PORT)
.handler(new ChannelInitializer() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new IdleStateHandler(READ_TIMEOUT,0,0),handler);
}
});
bs.connect();
}
static void connect(){
bs.connect().addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
if (future.cause() != null){
handler.startTime = -1;
handler.println("Failed to connect:" + future.cause());
}
}
});
}
}
- UptimeClientHandler
@ChannelHandler.Sharable
public class UptimeClientHandler extends SimpleChannelInboundHandler- UptimeServer
public final class UptimeServer {
private static final int PORT = Integer.parseInt(System.getProperty("port", "8080"));
private static final UptimeServerHandler handler = new UptimeServerHandler();
private UptimeServer(){}
public static void main(String[] args) throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup,workerGroup)
.channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(handler);
}
});
// Bind and start to accept incoming connections.
ChannelFuture f = b.bind(PORT).sync();
// Wait until the server socket is closed.
// In this example, this does not happen, but you can do that to gracefully
// shut down your server.
f.channel().closeFuture().sync();
}finally {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
}
- UptimeServerHandler
@ChannelHandler.Sharable
public class UptimeServerHandler extends SimpleChannelInboundHandler
