[英]how to send an int through UDP in java
I'm trying to write a bit of code which sends a single int over UDP. 我正在尝试编写一些通过UDP发送单个int的代码。 The code I have so far:
我到目前为止的代码:
Sender: 发件人:
int num = 2;
DatagramSocket socket = new DatagramSocket();
ByteArrayOutputStream bout = new ByteArrayOutputStream();
PrintStream pout = new PrintStream( bout );
pout.print(num);
byte[] barray = bout.toByteArray();
DatagramPacket packet = new DatagramPacket( barray, barray.length );
InetAddress remote_addr = InetAddress.getByName("localhost");
packet.setAddress( remote_addr );
packet.setPort(1989);
socket.send( packet );
Receiver: 接收器:
DatagramSocket socket = new DatagramSocket(1989);
DatagramPacket packet = new DatagramPacket(new byte[256] , 256);
socket.receive(packet);
ByteArrayInputStream bin = new ByteArrayInputStream(packet.getData());
for (int i=0; i< packet.getLength(); i++)
{
int data = bin.read();
if(data == -1)
break;
else
System.out.print((int) data);
The problem is the receiver is printing '50' to screen which is obviously not right. 问题是接收器正在向屏幕打印“50”,这显然是不对的。 I think that the problem may be that I'm somehow sending it as a string or something and its not reading it right.
我认为问题可能是我以某种方式将其作为字符串或其他东西发送而且它没有正确读取它。 Any help?
有帮助吗?
Use data streams like: 使用数据流,如:
import java.io.*;
public class Main {
public static void main(String[] args) throws Exception {
final ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
final DataOutputStream dataOut = new DataOutputStream(byteOut);
dataOut.writeInt(1);
dataOut.writeDouble(1.2);
dataOut.writeLong(4l);
dataOut.close(); // or dataOut.flush()
final byte[] bytes = byteOut.toByteArray();
final ByteArrayInputStream byteIn = new ByteArrayInputStream(bytes);
final DataInputStream dataIn = new DataInputStream(byteIn);
final int integ = dataIn.readInt();
final double doub = dataIn.readDouble();
final long lon = dataIn.readLong();
System.out.println(integ);
System.out.println(doub);
System.out.println(lon);
}
} }
InputStream.read() returns a single byte, not a 32-bit integer (see javadoc). InputStream.read()返回单个字节,而不是32位整数(请参阅javadoc)。 So what you want is
所以你想要的是
ObjectInputStream os = new ObjectInputStream(bin);
os.readInt();
The problem is that you're receiving CHAR CODE of '2' and not acctual 2 as integer. 问题是你收到的CHAR码为'2'而不是acctual 2为整数。 Try changing the your receiver code to:
尝试将您的接收器代码更改为:
DatagramSocket socket = new DatagramSocket(1989);
DatagramPacket packet = new DatagramPacket(new byte[256] , 256);
socket.receive(packet);
System.out.print(new String(packet.getData()));
But ObjectInputStream solution would work better for you I guess. 但是我想,ObjectInputStream解决方案对你来说会更好。
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