以编程方式关闭 netty
Posted
技术标签:
【中文标题】以编程方式关闭 netty【英文标题】：Shutdown netty programmatically 【发布时间】：2015-03-17 21:34:37 【问题描述】：我正在使用 netty 4.0.24.Final。
我需要以编程方式启动/停止 netty 服务器。 在启动服务器时，线程在
处被阻塞f.channel().closeFuture().sync()
请提供一些正确的提示。 下面是 Main 类调用的 EchoServer。 谢谢。
package nettytests;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
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;
public class EchoServer
private final int PORT = 8007;
private EventLoopGroup bossGroup;
private EventLoopGroup workerGroup;
public void start() throws Exception
// Configure the server.
bossGroup = new NioEventLoopGroup(1);
workerGroup = new NioEventLoopGroup(1);
try
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 100)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>()
@Override
public void initChannel(SocketChannel ch) throws Exception
ch.pipeline().addLast(new EchoServerHandler());
);
// Start the server.
ChannelFuture f = b.bind(PORT).sync();
// Wait until the server socket is closed. Thread gets blocked.
f.channel().closeFuture().sync();
finally
// Shut down all event loops to terminate all threads.
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
public void stop()
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
package nettytests;
public class Main
public static void main(String[] args) throws Exception
EchoServer server = new EchoServer();
// start server
server.start();
// not called, because the thread is blocked above
server.stop();
更新： 我通过以下方式更改了 EchoServer 类。这个想法是在一个新线程中启动服务器并保留到 EventLoopGroups 的链接。 这是正确的方法吗？
package nettytests;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
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;
/**
* Echoes back any received data from a client.
*/
public class EchoServer
private final int PORT = 8007;
private EventLoopGroup bossGroup;
private EventLoopGroup workerGroup;
public void start() throws Exception
new Thread(() ->
// Configure the server.
bossGroup = new NioEventLoopGroup(1);
workerGroup = new NioEventLoopGroup(1);
Thread.currentThread().setName("ServerThread");
try
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 100)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>()
@Override
public void initChannel(SocketChannel ch) throws Exception
ch.pipeline().addLast(new EchoServerHandler());
);
// Start the server.
ChannelFuture f = b.bind(PORT).sync();
// Wait until the server socket is closed.
f.channel().closeFuture().sync();
catch (InterruptedException e)
e.printStackTrace();
finally
// Shut down all event loops to terminate all threads.
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
).start();
public void stop() throws InterruptedException
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
【问题讨论】：
使用netty作为客户端时，使用f.channel().closeFuture().sync()，但是作为服务器使用时，使用f.channel().close().sync()。
【参考方案1】：
一种方法是制作类似的东西：
// once having an event in your handler (EchoServerHandler)
// Close the current channel
ctx.channel().close();
// Then close the parent channel (the one attached to the bind)
ctx.channel().parent().close();
这样做会得到以下结果：
// Wait until the server socket is closed. Thread gets blocked.
f.channel().closeFuture().sync();
主体部分不需要额外的线程。 现在的问题是：什么样的事件？这取决于你......可能是回声处理程序中的一条消息，作为“关闭”，将被视为关闭的顺序，而不仅仅是“退出”，它将变成仅关闭客户端通道。可能是别的……
如果您不处理子通道的关闭（因此通过您的处理程序）而是通过另一个进程（例如寻找存在的停止文件），那么您需要一个额外的线程来等待此事件，然后直接制作一个channel.close()，其中频道将是父频道（来自f.channel()），例如...
还有许多其他解决方案。
【讨论】：
【参考方案2】：我在关注官方教程时遇到了同样的问题。教程 有相同的模式：
f.channel().closeFuture().sync();
...
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
也就是说，频道在组关闭之前被关闭。我把顺序改成了这样：
bossGroup.shutdownGracefully().sync();
workerGroup.shutdownGracefully().sync();
f.channel().closeFuture().sync();
它奏效了。这导致了一个未锁定的服务器的粗略修改示例：
class Server
private ChannelFuture future;
private NioEventLoopGroup masterGroup;
private NioEventLoopGroup workerGroup;
Server(int networkPort)
masterGroup = new NioEventLoopGroup();
workerGroup = new NioEventLoopGroup();
try
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(masterGroup, workerGroup);
serverBootstrap.channel(NioServerSocketChannel.class);
serverBootstrap.option(ChannelOption.SO_BACKLOG,128);
serverBootstrap.childOption(ChannelOption.SO_KEEPALIVE,true);
serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>()
@Override
protected void initChannel(SocketChannel ch)
ch.pipeline().addLast(new InboundHandler());
).validate();
future = serverBootstrap.bind(networkPort).sync();
System.out.println("Started server on "+networkPort);
catch (Exception e)
e.printStackTrace();
shutdown();
void shutdown()
System.out.println("Stopping server");
try
masterGroup.shutdownGracefully().sync();
workerGroup.shutdownGracefully().sync();
future.channel().closeFuture().sync();
System.out.println("Server stopped");
catch (InterruptedException e)
e.printStackTrace();
【讨论】：
【参考方案3】：我刚刚关闭了事件循环组
bossGroup.shutdownGracefully().sync();
workerGroup.shutdownGracefully().sync();
而且效果很好，因为当我通过改造向代理服务器发送请求时，它说“连接失败”。
【讨论】：
以上是关于以编程方式关闭 netty的主要内容，如果未能解决你的问题，请参考以下文章