Java NIO实例UDP发送接收数据代码分享

Java的NIO包中，有一个专门用于发送UDP数据包的类：DatagramChannel，UDP是一种无连接的网络协议，
一般用于发送一些准确度要求不太高的数据等。

完整的服务端程序如下：

public class StatistiCSServer {  //每次发送接收的数据包大小  private final int MAX_BUFF_SIZE = 1024 * 10;  //服务端监听端口，客户端也通过该端口发送数据  private int port;  private DatagramChannel channel;  private Selector selector;  private ScheduledExecutorService es = Executors.newScheduledThreadPool(1);  public void init() throws ioException {    //创建通道和选择器    selector = Selector.open();    channel = DatagramChannel.open();    //设置为非阻塞模式    channel.configureBlocking(false);    channel.Socket().bind(new InetSocketAddress(port));    //将通道注册至selector，监听只读消息（此时服务端只能读数据，无法写数据）    channel.reGISter(selector, SelectionKey.OP_READ);    //使用线程的方式，保证服务端持续等待接收客户端数据    es.scheduleWithFixedDelay(new Runnable() {      @Override      public void run() {        try {          while(selector.select() > 0) {            Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();            while(iterator.hasNext()) {              SelectionKey key = iterator.next();              try {                iterator.remove();                if(key.isReadable()) {                  //接收数据                  doReceive(key);                }              } catch (Exception e) {                logger.error("SelectionKey receive exception", e);                try {                  if (key != null) {                    key.cancel();                    key.channel().close();                  }                } catch (ClosedChannelException cex) {                  logger.error("Close channel exception", cex);                }              }            }          }        } catch (IOException e) {          logger.error("selector.select exception", e);        }      }    }, 0L, 2L, TimeUnit.MINUTES);  }  //处理接收到的数据  private void doReceive(SelectionKey key) throws IOException {    String content = "";    DatagramChannel sc = (DatagramChannel) key.channel();    ByteBuffer buffer = ByteBuffer.allocate(MAX_BUFF_SIZE);    buffer.clear();    sc.receive(buffer);    buffer.flip();    while(buffer.hasRemaining()) {      byte[] buf = new byte[buffer.limit()];      buffer.get(buf);      content += new String(buf);    }    buffer.clear();    logger.debug("receive content="+content);    if(StringUtils.isNotBlank(content)) {      doSave(content);    }  } }