Question

使用SocketChannel sc =(SocketChannel)key.channel();，我们可以将数据从端口提取到缓冲区为了从端口连续接收数据而不丢失数据，代码应该如何？

这是我的代码

import java.io.*;
import java.net.*;
import java.nio.*;
import java.nio.channels.*;
import java.util.*;

public class MultiPortEcho
{
  private int ports[];
  private ByteBuffer echoBuffer = ByteBuffer.allocate(32000);

  public MultiPortEcho( int ports[] ) throws IOException
  {
    this.ports = ports;
    go();
  }

  private void go() throws IOException
  {
    // Create a new selector
    Selector selector = Selector.open();

    // Open a listener on each port, and register each one
    // with the selector
    for (int i=0; i<ports.length; ++i)
    {
      ServerSocketChannel ssc = ServerSocketChannel.open();
      ssc.configureBlocking( false );
      ServerSocket ss = ssc.socket();
      InetSocketAddress address = new InetSocketAddress( ports[i] );
      ss.bind( address );

      SelectionKey key = ssc.register( selector, SelectionKey.OP_ACCEPT );

      System.out.println( "Going to listen on "+ports[i] );
    }

    while (true)
    {
      int num = selector.select();
      System.out.println("num::::"+num);
      Set selectedKeys = selector.selectedKeys();
      Iterator it = selectedKeys.iterator();

      while (it.hasNext())
      {
        SelectionKey key = (SelectionKey)it.next();

        if ((key.readyOps() & SelectionKey.OP_ACCEPT)== SelectionKey.OP_ACCEPT)
          {
              // Accept the new connection
              ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
              SocketChannel sc = ssc.accept();
              sc.configureBlocking( false );

              // Add the new connection to the selector
              SelectionKey newKey = sc.register(selector,SelectionKey.OP_READ);
              it.remove();

              System.out.println( "Got connection from "+sc );
        }
          else if ((key.readyOps() & SelectionKey.OP_READ)== SelectionKey.OP_READ)
          {
              // Read the data
              SocketChannel sc =(SocketChannel)key.channel();
              System.out.println("sc::::"+sc);
              // data to fetched from channel and dump into the datatbase
              int bytesEchoed = 0;
              //while(true)
              {
                    echoBuffer.clear();
                    int r = sc.read(echoBuffer);
                    System.out.println("r:::" + r);
                    /*int pos=echoBuffer.position();
                    System.out.println("pos:::" +pos);*/
                    if (r == -1)
                    {
                        //echoBuffer.flip();
                        echoBuffer.rewind();
                        byte[] array = new byte[100000];
                        while (echoBuffer.hasRemaining())
                        {
                            int n = echoBuffer.remaining();
                            System.out.println("size:" + n);
                            echoBuffer.get(array,0,n );
                            System.out.println(new String(array,0,n));
                            key.cancel();
                            it.remove();

                        }

                    }

                    /*int pos=echoBuffer.position();
                    System.out.println("pos:::" + pos);
                    if(r<=0)
                    {
                        echoBuffer.flip();
                        for (int j = 0; j < pos; j++ )
                        {
                            String ss =Integer.toHexString(echoBuffer.get());
                            if (ss.length() == 1)
                                System.out.print("0" + ss + " ");
                            else if (ss.length() > 2)
                                System.out.print(ss.substring(6) + " ");
                            else System.out.print(ss + " ");
                        }
                      break;
                    }

                    echoBuffer.flip();

                    sc.write( echoBuffer );
                    bytesEchoed += r;*/
              }

             //System.out.println( "Echoed "+bytesEchoed+" from "+sc );
             //it.remove();
        }

      }

//System.out.println( "going to clear" );
//      selectedKeys.clear();
//System.out.println( "cleared" );
    }
  }

  static public void main( String args[] ) throws Exception
  {
    FileOutputStream fileoutputstream = new FileOutputStream("MultiPort.txt", false);
    PrintStream printstream = new PrintStream(fileoutputstream);
    System.setOut(printstream);
    if (args.length<=0) {
      System.err.println( "Usage: java MultiPortEcho port [port port ...]" );
      System.exit( 1 );
    }

    int ports[] = new int[args.length];

    for (int i=0; i<args.length; ++i) {
      ports[i] = Integer.parseInt( args[i] );
    }

    new MultiPortEcho( ports );
  }
}

Answer 1

您可以阅读的最大尺寸实际上受到您拥有的内存量的限制。

但是，您无需读取超大块以提高效率。你会发现1 MB就足够了。实际上，您可能会发现4KB的块足够大，可以为1 Gb连接获得最大带宽。

Answer 2

对总体设计的评论：

编写网络服务器有两种基本方法。阻止和非阻塞。 2008年，我们的任务是在Python中实现高性能网络服务器。在尝试了几种不同阻止的方式之后，我们发现更容易并且使用起来更清晰：

阻止套接字
每个连接一个帖子
几个经理主题

这样每个线程都可以坐下来等待数据，直到它死亡的那一天，当它收到一个完整的数据包时，它就会采取行动。

仅供考虑。

Answer 3

您可以在此SocketChannelHandler中找到一些潜在客户，readFromChannel()函数可能会对您感兴趣。

        public void readFromChannel() {
        try {
                   [...]
                   if (readBuffer != null) {
                readBuffer.flip();
                receivingBroker.broker(readBuffer, false);
                if (readBuffer != null) {
                    readBuffer.clear();
                    readBuffer = null;
                }
            }
            if (readBuffer == null || !readBuffer.hasRemaining()) {
                getThread().removeInterestOp(this, SelectionKey.OP_READ);
                getThread().addInterestOp(this, SelectionKey.OP_WRITE);
            }
            if (receivingBroker.isClosed()) {
                if (getChannelListener() != null) {
                    getChannelListener().readFinished(this);
                }
            }
         } catch (Exception e) {
              e.printStackTrace();
         }
         }

Answer 4

作为第一个修复，您应该使用key.cancel（）删除该行。保留它将取消密钥，并确保在第一次阅读后不考虑密钥 - 这将有效地阻止您事后阅读。

Answer 5

当您使用NIO接受连接时，您可以获取套接字并设置相应的输入/输出缓冲区大小。

socketChannel.socket().setReceiveBufferSize(512);
socketChannel.socket().setSendBufferSize(16);

由于NIO大量使用操作系统的网络堆栈，这只是一个提示。所有这些实际上都记录在Socket JavaDoc

中

使用java中nio包的socketChannel从客户端套接字获取的最大数据大小

5 个答案: