我必须发送一个 UDP 数据包并从 UDP 服务器获得响应。我虽然 UDP 与 Java 中的 java.net.DatagramPacket 类似,但 DatagramPacket 的文档似乎是您发送了一个数据包但没有得到任何返回,这是正确的使用方法还是我应该使用 java。网络套接字
4 回答
UDP数据报发送和接收示例(来源):
import java.io.*;
import java.net.*;
class UDPClient
{
public static void main(String args[]) throws Exception
{
BufferedReader inFromUser =
new BufferedReader(new InputStreamReader(System.in));
DatagramSocket clientSocket = new DatagramSocket();
InetAddress IPAddress = InetAddress.getByName("localhost");
byte[] sendData = new byte[1024];
byte[] receiveData = new byte[1024];
String sentence = inFromUser.readLine();
sendData = sentence.getBytes();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 9876);
clientSocket.send(sendPacket);
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
clientSocket.receive(receivePacket);
String modifiedSentence = new String(receivePacket.getData());
System.out.println("FROM SERVER:" + modifiedSentence);
clientSocket.close();
}
}
您必须使用 DatagramPacket 和 DatagramSocket。当你发送一个数据包时,你只是发送一个数据包。但是,当您收到一个数据包时,您可以获得一个从另一个程序发送的数据包(例如服务器回复)
http://docs.oracle.com/javase/7/docs/api/java/net/DatagramSocket.html
套接字仅用于 TCP 连接。
Java 文档确实涵盖了如何编写客户端和服务器。
http://docs.oracle.com/javase/tutorial/networking/datagrams/clientServer.html
You want to look at DatagramSocket#receive
That's precisely the distinction between UDP and TCP sockets.
UDP is broadcast, whereas TCP with java.net.Socket is point to point. UDP is fire-and-forget, analogous to publishing a message on a JMS Topic.
See: http://docs.oracle.com/javase/tutorial/networking/datagrams/index.html