[英]Communication between Java programs with DatagramSocket
我正在嘗試交流兩個Java程序,對此沒有問題。 程序A發送帶有單詞“ token”的消息,程序B收到該消息並打印。 我的問題是我想在消息長度之前發送給程序B,以創建具有正確長度的數組,但是我不知道該怎么做。
public class ProgramA {
public static void main(String[] args) {
try {
DatagramSocket datagramSocket = new DatagramSocket();
String message = "token";
InetAddress addr = InetAddress.getByName("localhost");
DatagramPacket datagram = new DatagramPacket(message.getBytes(),message.getBytes().length, addr, 5556);
datagramSocket.send(datagram);
datagramSocket.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
public class ProgramB {
public static void main(String[] args) {
try {
InetSocketAddress addr = new InetSocketAddress("localhost", 5556);
DatagramSocket datagramSocket = new DatagramSocket(addr);
byte[] message = new byte[5];
DatagramPacket datagram = new DatagramPacket(message, message.length);
datagramSocket.receive(datagram);
datagramSocket.close();
for(int i = 0; i < message.length; i++) {
System.out.print((char)message[i]);
}
}
catch (IOException e)
{
e.printStackTrace();
}
}
如果您知道消息的長度最大為X個字節,則可以使用以下內容:
package experiment;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class ProgramA {
public static void main(String[] args) {
try {
System.out.println("Started");
DatagramSocket datagramSocket = new DatagramSocket();
String message = "tokenasdfasdfasdfasdf";
InetAddress addr = InetAddress.getByName("localhost");
DatagramPacket datagramLength = new DatagramPacket(new byte[]{(byte)message.length()}, 1, addr, 5556);
DatagramPacket datagram = new DatagramPacket(message.getBytes(),message.getBytes().length, addr, 5556);
datagramSocket.send(datagramLength);
datagramSocket.send(datagram);
datagramSocket.close();
System.out.println("Done");
}
catch (IOException e) {
e.printStackTrace();
}
}
}
package experiment;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
public class ProgramB {
public static void main(String[] args) {
try {
InetSocketAddress addr = new InetSocketAddress("localhost", 5556);
DatagramSocket datagramSocket = new DatagramSocket(addr);
byte[] messageLength = new byte[1];
DatagramPacket datagramLength = new DatagramPacket(messageLength, 1);
datagramSocket.receive(datagramLength);
byte[] message = new byte[(int)messageLength[0]];
DatagramPacket datagram = new DatagramPacket(message, message.length);
datagramSocket.receive(datagram);
datagramSocket.close();
for(int i = 0; i < message.length; i++) {
System.out.print((char)message[i]);
}
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
假設郵件的長度不超過127,則可以正常工作; 否則,帶有消息長度的datagramPacket必須包含一個以上的字節
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