使用Java NIO编写高性能的服务器 文件下载(2)

 

下面是客户端请求的代码，也比较简单，模拟100个用户同时下载文件。

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);
  static CharsetEncoder encoder = Charset.forName("GB2312").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();
  }
}