State management
1.业务状态管理-是否登录
A ChannelHandler often needs to store some stateful information. The simplest and recommended approach is to use member variables:
public interface Message {
// your methods here
}
public class DataServerHandler extends SimpleChannelInboundHandler<Message> {
private boolean loggedIn;
@Override
public void channelRead0(ChannelHandlerContext ctx, Message message) {
Channel ch = e.getChannel();
if (message instanceof LoginMessage) {
authenticate((LoginMessage) message);
loggedIn = true;
} else (message instanceof GetDataMessage) {
if (loggedIn) {
ch.write(fetchSecret((GetDataMessage) message));
} else {
fail();
}
}
}
...
}
Because the handler instance has a state variable which is dedicated to one connection, you have to create a new handler instance for each new channel to avoid a race condition where a unauthenticated client can get the confidential information:
// Create a new handler instance per channel.
// See ChannelInitializer.initChannel(Channel).
public class DataServerInitializer extends ChannelInitializer<Channel> {
@Override
public void initChannel(Channel channel) {
channel.pipeline().addLast("handler", new DataServerHandler());
}
}
2。channel 自身状态管理
public class HeartbeatHandlerInitializer extends ChannelInitializer<Channel> {
private static final int READ_IDEL_TIME_OUT = 10; // 读超时
private static final int WRITE_IDEL_TIME_OUT = 10;// 写超时
private static final int ALL_IDEL_TIME_OUT = 0; // 所有超时
@Override
protected void initChannel(Channel ch) throws Exception {
System.out.println( "channelId" + ch.id());
//一直执行，一直打印
while (ch.eventLoop().iterator().hasNext()){
System.out.println(ch.eventLoop().iterator().next().inEventLoop());
}
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(new IdleStateHandler(READ_IDEL_TIME_OUT, WRITE_IDEL_TIME_OUT, ALL_IDEL_TIME_OUT, TimeUnit.SECONDS)); //
pipeline.addLast(new HeartbeatServerHandler());
}
}