Java Socket学习笔记（四）- NIO TCP实践_JAVA_编程开发_程序员俱乐部

一、回传协议接口和TCP方式实现：

1.接口：

class="java" name="code">import java.nio.channels.SelectionKey;
import java.io.IOException;

public interface EchoProtocol {
  void handleAccept(SelectionKey key) throws IOException;
  void handleRead(SelectionKey key) throws IOException;
  void handleWrite(SelectionKey key) throws IOException;
}

?2.实现：

import java.nio.channels.*;
import java.nio.ByteBuffer;
import java.io.IOException;

public class TCPEchoSelectorProtocol implements EchoProtocol{
    private int bufSize; // Size of I/O buffer

    public EchoSelectorProtocol(int bufSize) {
        this.bufSize = bufSize;
    }

    public void handleAccept(SelectionKey key) throws IOException {
        SocketChannel clntChan = ((ServerSocketChannel) key.channel()).accept();
        clntChan.configureBlocking(false); // Must be nonblocking to register
        // Register the selector with new channel for read and attach byte buffer
        clntChan.register(key.selector(), SelectionKey.OP_READ, ByteBuffer.allocate(bufSize));
        
    }

    public void handleRead(SelectionKey key) throws IOException {
        // Client socket channel has pending data
        SocketChannel clntChan = (SocketChannel) key.channel();
        ByteBuffer buf = (ByteBuffer) key.attachment();
        long bytesRead = clntChan.read(buf);
        if (bytesRead == -1) { // Did the other end close?
            clntChan.close();
        } else if (bytesRead > 0) {
            // Indicate via key that reading/writing are both of interest now.
            key.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE);
        }
    }

    public void handleWrite(SelectionKey key) throws IOException {
        /*
         * Channel is available for writing, and key is valid (i.e., client channel 
         * not closed).
         */
        // Retrieve data read earlier
        ByteBuffer buf = (ByteBuffer) key.attachment();
        buf.flip(); // Prepare buffer for writing
        SocketChannel clntChan = (SocketChannel) key.channel();
        clntChan.write(buf);
        if (!buf.hasRemaining()) { // Buffer completely written? 
            //Nothing left, so no longer interested in writes
            key.interestOps(SelectionKey.OP_READ);
        }
        buf.compact(); // Make room for more data to be read in
    }

}

?

二、NIO?TCP客户端：

import java.net.InetSocketAddress;
import java.net.SocketException;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;

public class TCPEchoClientNonblocking {

    public static void main(String args[]) throws Exception {
        String server = "127.0.0.1"; // Server name or IP address
        // Convert input String to bytes using the default charset
        byte[] argument = "0123456789abcdefghijklmnopqrstuvwxyz".getBytes();

        int servPort = 5500;

        // Create channel and set to nonblocking
        SocketChannel clntChan = SocketChannel.open();
        clntChan.configureBlocking(false);

        // Initiate connection to server and repeatedly poll until complete
        if (!clntChan.connect(new InetSocketAddress(server, servPort))) {
            while (!clntChan.finishConnect()) {
                System.out.print("."); // Do something else
            }
        }
        ByteBuffer writeBuf = ByteBuffer.wrap(argument);
        ByteBuffer readBuf = ByteBuffer.allocate(argument.length);
        int totalBytesRcvd = 0; // Total bytes received so far
        int bytesRcvd; // Bytes received in last read
        while (totalBytesRcvd < argument.length) {
            if (writeBuf.hasRemaining()) {
                clntChan.write(writeBuf);
            }
            if ((bytesRcvd = clntChan.read(readBuf)) == -1) {
                throw new SocketException("Connection closed prematurely");
            }
            totalBytesRcvd += bytesRcvd;
            System.out.print("."); // Do something else
        }

        System.out.println("Received: " + // convert to String per default charset
                new String(readBuf.array(), 0, totalBytesRcvd).length());
        clntChan.close();
    }
}

?

三、NIO?TCP服务端：

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.channels.*;
import java.util.Iterator;

public class TCPServerSelector {
    private static final int BUFSIZE = 256; // Buffer size (bytes)
    private static final int TIMEOUT = 3000; // Wait timeout (milliseconds)
    
    public static void main(String[] args) throws IOException {
        int[] ports = {5500};
        // Create a selector to multiplex listening sockets and connections
        Selector selector = Selector.open();

        // Create listening socket channel for each port and register selector
        for (int port : ports) {
            ServerSocketChannel listnChannel = ServerSocketChannel.open();
            listnChannel.socket().bind(new InetSocketAddress(port));
            listnChannel.configureBlocking(false); // must be nonblocking to register
            // Register selector with channel. The returned key is ignored
            listnChannel.register(selector, SelectionKey.OP_ACCEPT);
        }

        // Create a handler that will implement the protocol
        TCPProtocol protocol = new EchoSelectorProtocol(BUFSIZE);

        while (true) { // Run forever, processing available I/O operations
            // Wait for some channel to be ready (or timeout)
            if (selector.select(TIMEOUT) == 0) { // returns # of ready chans
                System.out.print(".");
                continue;
            }

            // Get iterator on set of keys with I/O to process
            Iterator<SelectionKey> keyIter = selector.selectedKeys().iterator();
            while (keyIter.hasNext()) {
                SelectionKey key = keyIter.next(); // Key is bit mask
                // Server socket channel has pending connection requests?
                if (key.isAcceptable()) {
                    System.out.println("----accept-----");
                    protocol.handleAccept(key);
                }
                // Client socket channel has pending data?
                if (key.isReadable()) {
                    System.out.println("----read-----");
                    protocol.handleRead(key);
                }
                // Client socket channel is available for writing and 
                // key is valid (i.e., channel not closed)?
                if (key.isValid() && key.isWritable()) {
                    System.out.println("----write-----");
                    protocol.handleWrite(key);
                }
                keyIter.remove(); // remove from set of selected keys
            }
        }
    }
    
}

?

?

?参考：

1.《Java TCP/IP Socket编程(原书第2版)》