Netty Study Notes

1, in the absence of any encoder, decoder situation, Netty send and receive data are in accordance with the form of bytebuf, other forms are not legal.

Bytebuf result = (BYTEBUF) msg;byte[] data = new Byte[result.readablebytes ()];result.readbytes (data); String resultstr = new string (data),//receives and prints the client's information System.out.println ("Client said:" + resultstr);//Release resources, This line is critical result.release ();//Send a message to the client string response = "I am ok!"; /In the current scenario, the data sent must be converted to the BYTEBUF array bytebuf encoded = Ctx.alloc (). Buffer (4 * response.length ()); Encoded.writebytes ( Response.getbytes ()); Ctx.write (encoded); Ctx.flush ();

2, receive sends the data operation all is realizes through the handler, handler occupies the very important position in the Netty.

Class Helloserverinhandler extends Channelinboundhandleradapter

3, Netty handler is event-triggered, for example, when client connection server succeeds, the Channelactive method of Helloclientinthandler in client is automatically called.

Receives the server-side message and prints it out @Overridepublic void Channelread (Channelhandlercontext ctx, Object msg) throws Exception { SYSTEM.OUT.PRINTLN ("Client Channelread");  Bytebuf result = (bytebuf) msg; Byte[] data=new byte[result.readablebytes ()];result.readbytes (data); SYSTEM.OUT.PRINTLN ("Server said:" + new String (data)); Result.release ();}

4, the transfer between Channelinboundhandler, by calling Ctx.firechannelread (msg) implementation; Call Ctx.write (msg) is passed to Channeloutboundhandler.

@Overridepublic void Channelread (Channelhandlercontext ctx, Object msg) throws Exception {Log.debug ("InboundHandler1 Channelread "+ctx); Ctx.firechannelread (msg);} @Overridepublic void Channelread (Channelhandlercontext ctx, Object msg) throws Exception {Log.debug ("InboundHandler2 Channelread "+ctx); Bytebuf result= (BYTEBUF) msg;byte[] data=new byte[result.readablebytes ()]; String Res=new string (data); SYSTEM.OUT.PRINTLN ("Client said:" +res); Result.release (); Ctx.write (msg);}

5. After the Ctx.write () method executes, the flush () method needs to be called to make it execute immediately.

@Overridepublic void Write (Channelhandlercontext ctx, Object msg,channelpromise Promise) throws Exception {Log.debug (" OutboundHandler1 write "); String str= "I am OK"; Bytebuf encoded=ctx.alloc (). Buffer (Str.length ()); Encoded.writebytes (Str.getbytes ()); Ctx.write (encoded); Ctx.flush ();}

6, Channeloutboundhandler in the registration time needs to be placed before the last Channelinboundhandler, otherwise it will not be delivered to Channeloutboundhandler.

Channelpipeline Pipeline=ch.pipeline ();    Pipeline.addlast (New OutboundHandler1 ());p Ipeline.addlast (New OutboundHandler2 ()); Pipeline.addlast (New InboundHandler1 ());p Ipeline.addlast (New InboundHandler2 ());

7, Encoder, decoder nature is also handler, their execution order, use method and handler consistent.

Execution order is: Encoder first registered after execution, and outboundhandler consistent; decoder is first registered first executed, and Inboundhandler consistent.