Java Socket编程实例（四）- NIO TCP实践

一、回传协议接口和tcp方式实现：

1.接口：

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 tcpechoselectorprotocol(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 
      } 
    } 
  } 
   
} 

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