java DatagramSocket接收数据组播Socket发送数据

发布于 2024-10-06 14:06:26 字数 66 浏览 2 评论 0 原文

任何人都可以向我展示一个 java 示例，用于从 DatagramSocket 接收数据并通过多播套接字发送相同的数据

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ゝ杯具 2024-10-13 14:06:26

发送多播数据报

为了在 Java 中发送任何类型的数据报，无论是单播、广播还是多播，都需要一个 java.net.DatagramSocket：

DatagramSocket socket = new DatagramSocket();

可以选择提供一个套接字必须绑定到的 DatagramSocket 构造函数的本地端口。仅当需要其他方能够在特定港口联系我们时才需要这样做。第三个构造函数采用本地端口和要绑定的本地 IP 地址。这（很少）用于多宿主主机，在多宿主主机上接收流量的网络适配器很重要。

 DatagramSocket socket = new DatagramSocket();

byte[] b = new byte[DGRAM_LENGTH];
DatagramPacket dgram;

dgram = new DatagramPacket(b, b.length,
  InetAddress.getByName(MCAST_ADDR), DEST_PORT);

System.err.println("Sending " + b.length + " bytes to " +
  dgram.getAddress() + ':' + dgram.getPort());
while(true) {
  System.err.print(".");
  socket.send(dgram);
  Thread.sleep(1000);
}

接收多播数据报

人们可以使用普通的 DatagramSocket 来发送和接收单播和广播数据报以及发送多播数据报。然而，为了接收多播数据报，需要一个 MulticastSocket。原因很简单，UDP 以下的所有协议层都需要做额外的工作来控制和接收多播流量。

byte[] b = new byte[BUFFER_LENGTH];
DatagramPacket dgram = new DatagramPacket(b, b.length);
MulticastSocket socket =
  new MulticastSocket(DEST_PORT); // must bind receive side
socket.joinGroup(InetAddress.getByName(MCAST_ADDR));

while(true) {
  socket.receive(dgram); // blocks until a datagram is received
  System.err.println("Received " + dgram.getLength() +
    " bytes from " + dgram.getAddress());
  dgram.setLength(b.length); // must reset length field!
}

有关更多信息：

Sending multicast datagrams

In order to send any kind of datagram in Java, be it unicast, broadcast or multicast, one needs a java.net.DatagramSocket:

DatagramSocket socket = new DatagramSocket();

One can optionally supply a local port to the DatagramSocket constructor to which the socket must bind. This is only necessary if one needs other parties to be able to reach us at a specific port. A third constructor takes the local port AND the local IP address to which to bind. This is used (rarely) with multi-homed hosts where it is important on which network adapter the traffic is received.

 DatagramSocket socket = new DatagramSocket();

byte[] b = new byte[DGRAM_LENGTH];
DatagramPacket dgram;

dgram = new DatagramPacket(b, b.length,
  InetAddress.getByName(MCAST_ADDR), DEST_PORT);

System.err.println("Sending " + b.length + " bytes to " +
  dgram.getAddress() + ':' + dgram.getPort());
while(true) {
  System.err.print(".");
  socket.send(dgram);
  Thread.sleep(1000);
}

Receiving multicast datagrams

One can use a normal DatagramSocket to send and receive unicast and broadcast datagrams and to send multicast datagrams. In order to receive multicast datagrams, however, one needs a MulticastSocket. The reason for this is simple, additional work needs to be done to control and receive multicast traffic by all the protocol layers below UDP.

byte[] b = new byte[BUFFER_LENGTH];
DatagramPacket dgram = new DatagramPacket(b, b.length);
MulticastSocket socket =
  new MulticastSocket(DEST_PORT); // must bind receive side
socket.joinGroup(InetAddress.getByName(MCAST_ADDR));

while(true) {
  socket.receive(dgram); // blocks until a datagram is received
  System.err.println("Received " + dgram.getLength() +
    " bytes from " + dgram.getAddress());
  dgram.setLength(b.length); // must reset length field!
}

For more Information: