Java NiO for non-blocking socket communication

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Java provides sockets and ServerSocket packets for network communication, but the implementation is blocking, with only one connection at a time, which leads to a bad experience. Of course, we can also manage connections by constantly creating threads, but with more threads it can reduce efficiency. So Java introduced the non-blocking io--channel. And the channel provides the relevant channel for network communication.

The channel merges the traditional input and output streams, meaning that a channel can either input content or output content.

And, using the channel, the buffer provided by NIO should be used as an intermediary.

Channel Type:

• FileChannel
• Datagramchannel
• Socketchannel
• Serversocketchannel

Buffer type:

• Bytebuffer
• Charbuffer
• DoubleBuffer
• Floatbuffer
• Intbuffer
• Longbuffer
• Shortbuffer

In order to use Socketchannel and Serversocketchannel, create a bytebuffer using Factory mode:

Bytebuffer Bytebuffer = bytebuffer.allocate (12);

To create the Channel method:

Serversocketchannel Serversocketchannel = Serversocketchannel.open ();

The following statement sets the specified channel to non-blocking:

Serversocketchannel.configureblocking (false);

Binding to a port:

Serversocketchannel.bind (new inetsocketaddress (PORT));

The corresponding if is Socketchannel, method is connect, here only take serversocketchannel example.

So far, we haven't seen how the channel implements non-blocking IO, so NIO provides a tool--selector.

Selector, in short, is a management tool for multiple channel, we can add multiple channel to a brain, if which channel is ready to read or write (or other operations) will notify us.

There is a interest concept in Selector, which means that when we register a channel with selector, we indicate what kind of behavior selector want to monitor the channel, after all, a channel can be read,write,accept, Connect

Selector instantiation:

Selector Selector = Selector.open ();

Channel Registration

Serversocketchannel.register (selector, selectionkey.op_accept);

The second argument is a interest type

Interest Type:

1. Selectionkey.op_connect
2. Selectionkey.op_accept
3. Selectionkey.op_read
4. Selectionkey.op_write

In general, we can register an accept for Serversocketchannel.

Then, when we call Selector.select (), selector waits for the channel that has been registered until a channel is ready. This process is blocking, of course, what is the relationship between blocking, in fact, IO or non-blocking.

We then refer to Selector.selectedkeys () to return a collection that contains a response channel, iteration set, and we get a channel.

Well, it's not about getting the channel, it's another thing--selectionkey.

Selectionkey contains a lot of information, you can get his selector,channel and registration information.

We can obtain information about our registration through selectionkey.isreadable,isacceptable,isconnectable,iswritable, and then deal with each type of response specifically.

Also, remember to remove the object after the iteration.

Java NiO for non-blocking socket communication