500块钱一个问题

Question

在做j2se中用socket传输文件速度很慢，大概30k/s，如果谁能解决这个速度问题，提高到100k/s左右，将给予500块的酬劳。
[b]问题补充：[/b]
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Answer 1

用nio异步I/O来实现socket传输就快多了

[code="java"]
package nio.file;

import java.io.FileInputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.util.Iterator;

/**

• 测试文件下载的NIOServer

• @author tenyears.cn
  */
  public class NIOServer {
  static int BLOCK = 4096;
  static String charCoding = "utf-8";
  // 处理与客户端的交互
  public class HandleClient {
  protected FileChannel channel;
  protected ByteBuffer buffer;

  public HandleClient() throws IOException {
      this.channel = new FileInputStream(filename).getChannel();
      this.buffer = ByteBuffer.allocate(BLOCK);
  }
  
  public ByteBuffer readBlock() {
      try {
          buffer.clear();
          int count = channel.read(buffer);
          buffer.flip();
          if (count <= 0)
              return null;
      } catch (IOException e) {
          e.printStackTrace();
      }
      return buffer;
  }
  
  public void close() {
      try {
          channel.close();
      } catch (IOException e) {
          e.printStackTrace();
      }
  }
  

  }

  protected Selector selector;
  protected String filename = "c:\file.war"; // a big file
  protected ByteBuffer clientBuffer = ByteBuffer.allocate(BLOCK);
  protected CharsetDecoder decoder;

  public NIOServer(int port) throws IOException {
  selector = this.getSelector(port);
  Charset charset = Charset.forName(charCoding);
  decoder = charset.newDecoder();
  }

  // 获取Selector
  protected Selector getSelector(int port) throws IOException {
  ServerSocketChannel server = ServerSocketChannel.open();
  Selector sel = Selector.open();
  server.socket().bind(new InetSocketAddress(port));
  server.configureBlocking(false);
  server.register(sel, SelectionKey.OP_ACCEPT);
  return sel;
  }

  // 监听端口
  public void listen() {
  try {
  for (;;) {
  selector.select();
  Iterator iter = selector.selectedKeys()
  .iterator();
  while (iter.hasNext()) {
  SelectionKey key = iter.next();
  iter.remove();
  handleKey(key);
  }
  }
  } catch (IOException e) {
  e.printStackTrace();
  }
  }

  // 处理事件
  protected void handleKey(SelectionKey key) throws IOException {
  if (key.isAcceptable()) { // 接收请求
  ServerSocketChannel server = (ServerSocketChannel) key.channel();
  SocketChannel channel = server.accept();
  channel.configureBlocking(false);
  channel.register(selector, SelectionKey.OP_READ);
  } else if (key.isReadable()) { // 读信息
  SocketChannel channel = (SocketChannel) key.channel();
  int count = channel.read(clientBuffer);
  if (count > 0) {
  clientBuffer.flip();
  CharBuffer charBuffer = decoder.decode(clientBuffer);
  System.out.println("Client >>" + charBuffer.toString());
  SelectionKey wKey = channel.register(selector,
  SelectionKey.OP_WRITE);
  wKey.attach(new HandleClient());
  } else
  channel.close();
  clientBuffer.clear();
  } else if (key.isWritable()) { // 写事件
  SocketChannel channel = (SocketChannel) key.channel();
  HandleClient handle = (HandleClient) key.attachment();
  ByteBuffer block = handle.readBlock();
  if (block != null)
  channel.write(block);
  else {
  handle.close();
  channel.close();
  }
  }
  }

  public static void main(String[] args) {
  int port = 12345;
  try {
  NIOServer server = new NIOServer(port);
  System.out.println("Listernint on " + port);
  while (true) {
  server.listen();
  }
  } catch (IOException e) {
  e.printStackTrace();
  }
  }
  }

[/code]

[code="java"]
package nio.file;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.util.Iterator;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**

• 文件下载客户端

• @author tenyears.cn
  */
  public class NIOClient {
  static int SIZE = 100;
  static InetSocketAddress ip = new InetSocketAddress("localhost", 12345);

  // CharsetDecorder并不是线程安全的，在高并发的状态下会出问题。
  static CharsetEncoder encoder = Charset.forName("utf-8").newEncoder();

  static class Download implements Runnable {
  protected int index;

  public Download(int index) {
      this.index = index;
  }
  
  public void run() {
      try {
          long start = System.currentTimeMillis();
          SocketChannel client = SocketChannel.open();
          client.configureBlocking(false);
          Selector selector = Selector.open();
          client.register(selector, SelectionKey.OP_CONNECT);
          client.connect(ip);
          ByteBuffer buffer = ByteBuffer.allocate(8 * 1024);
          int total = 0;
          FOR: for (;;) {
              selector.select();
              Iterator<SelectionKey> iter = selector.selectedKeys()
                      .iterator();
              while (iter.hasNext()) {
                  SelectionKey key = iter.next();
                  iter.remove();
                  if (key.isConnectable()) {
                      SocketChannel channel = (SocketChannel) key
                              .channel();
                      if (channel.isConnectionPending())
                          channel.finishConnect();
                      channel.write(encoder.encode(CharBuffer
                              .wrap("Hello from " + index)));
                      channel.register(selector, SelectionKey.OP_READ);
                  } else if (key.isReadable()) {
                      SocketChannel channel = (SocketChannel) key
                              .channel();
                      int count = channel.read(buffer);
                      if (count > 0) {
                          total += count;
                          buffer.clear();
                      } else {
                          client.close();
                          break FOR;
                      }
                  }
              }
          }
          double last = (System.currentTimeMillis() - start) * 1.0 / 1000;
          System.out.println("Thread " + index + " downloaded " + total
                  + "bytes in " + last + "s.");
      } catch (IOException e) {
          e.printStackTrace();
      }
  }
  

  }

  public static void main(String[] args) throws IOException {
  ExecutorService exec = Executors.newFixedThreadPool(SIZE);
  for (int index = 0; index < SIZE; index++) {
  exec.execute(new Download(index));
  }
  exec.shutdown();
  }
  }

[/code]