An echo server example implemented using Java IO, NIO, Netty, respectively

Use Java IO, Java NIO, Netty to implement a simple echoserver (that is, returning the client's input information as is).

Java IO

int port = 9000;  ServerSocket ss = new ServerSocket (port), while (true) {final socket socket = ss.accept (), New Thread (new Runnable () {public  void Run () {while (true) {try {bufferedinputstream in = new Bufferedinputstream (Socket.getinputstream ()); byte[] buf = new Byte[1024];int len = In.read (BUF); Read message from clientstring message = new String (buf, 0, Len); Bufferedoutputstream out = new Bufferedoutputstream (Socket.getoutputstream ()); Out.write (Message.getbytes ()); Echo to Clientout.flush ();} catch (IOException e) {e.printstacktrace ();}}}}). Start ();}

The actual effect is demonstrated with Telnet, as follows:

$ telnet 127.0.0.1 9000Trying 127.0.0.1...Connected to 127.0.0.1.Escape character is ' ^] '. Hihi Hello, hello.

Java IO Disadvantages:

You need to create a thread for each client connection.

Java NIO

Serversocketchannel sschannel = serversocketchannel.open ();int port = 9001; Sschannel.bind (new inetsocketaddress (port)); Selector selector = selector.open (); sschannel.configureblocking (false); SsChannel.register ( selector, selectionkey.op_accept);  //Register Listener connection request while  (True)  {selector.select ();//blocking   Until an event registered by a channel is triggered Set<selectionkey> keys = selector.selectedkeys ();for  ( Selectionkey key : keys)  {if  (key.isacceptable ())  { // Client connection Request serversocketchannel ssc =  (Serversocketchannel)  key.channel (); Socketchannel sc = ssc.accept (); sc.configureblocking (false); Sc.register (selector,  Selectionkey.op_read);  //Register Listener Client Input}if (key.isreadable ()) { //Client input socketchannel sc =  ( Socketchannel)  key.channel (); Bytebuffer buffer = bytebuffer.allocate (1024x768); sc.read (buffer); Buffer.flip (); sc.write (buffer);}} KeYs.clear ();} 

Advantages:

Event drivers can manage multiple connections (channel) through one thread

But be aware that not every scenario is nio better than IO.

Netty

public class nettyechoserver {public class echoserverhandler extends  channelhandleradapter {@Overridepublic  void channelread (channelhandlercontext ctx,  object msg)  { //ehco to clientctx.write (msg); Ctx.flush ();} @Overridepublic  void exceptioncaught (Channelhandlercontext ctx, throwable cause)  {// Close the connection when an exception is  Raised.cause.printStackTrace (); Ctx.close ();}} Private int port;public nettyechoserver (Int port)  {this.port = port;} Public void run ()  throws exception {eventloopgroup bossgroup = new  nioeventloopgroup ();  eventloopgroup workergroup = new nioeventloopgroup (); try  {serverbootstrap b = new serverbootstrap ();  b.group (BossGroup, workerGroup ). Channel (nioserversocketchannel.cl). Childhandler (new channelinitializer<socketchannel> ()  {  @Overridepublic  void  initchannel (Socketchannel ch) Throws exception {ch.pipeline (). AddLast (new  Echoserverhandler ());}). Option (channeloption.so_backlog, 128)  .childoption (channeloption.so_keepalive, true);  //  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 ();}} Public static void main (String[] args)  throws exception {int port  = 9002;new nettYechoserver (Port). Run ();}} 

The previous example is excerpted from the official documentation.

Advantages:

It seems that you only need to inherit channelhandleradapter and then overwrite the appropriate method.

Reference Documentation:

Http://en.wikipedia.org/wiki/Non-blocking_I/O_ (Java)

Https://today.java.net/pub/a/today/2007/02/13/architecture-of-highly-scalable-nio-server.html

Http://www.javaworld.com/article/2078654/java-se/java-se-five-ways-to-maximize-java-nio-and-nio-2.html

Http://netty.io/wiki/user-guide-for-5.x.html

An echo server example implemented using Java IO, NIO, Netty, respectively