Question

我正在尝试实现UDP客户端服务器。客户端使用rdt_send函数发送1032个字节，但服务器仅在客户端执行两次后才接收此数据包。

以下是代码：

rdt_send：

public void rdt_send(byte[] buffer, Integer mss, DatagramSocket s,Integer seqNum) throws IOException
{
    int i,j,k;
    byte[] seq_num = new byte[4];
    byte[] seqnum_temp = new byte[4];
    byte [] checksum = new byte[2];
    byte [] udp_field = new BigInteger("0101010101010101",2).toByteArray();
    Integer checksum_value = (int)calculateChecksum(buffer);
    checksum = new BigInteger(checksum_value.toString(), 10).toByteArray();
    seqnum_temp = new BigInteger(seqNum.toString(),10).toByteArray();
    System.out.println(checksum_value);
    Integer length_temp = seqnum_temp.length;
    if (seqnum_temp.length<4)
    {
        Integer append = 4 -seqnum_temp.length;
        for (i=0;i<append;i++)
        {
            seq_num[i] = 0;
        }
        for (j = append,  k=0 ; j<4 && k<length_temp ; j++,k++)
        {
            seq_num[j] = seqnum_temp[k];
        }

        System.out.println(seq_num[0]);
    }

    byte[] finalSend = new byte[mss+8];

    for (i=0;i<4;i++)
    {
        finalSend[i] = seq_num[i];

    }
    for (i=4,k=0;i<6 && k<2;i++,k++)
    {
        finalSend[i] = checksum[k];
    }
    for (i=6,k=0;i<8 && k<2 ;i++,k++)
    {
        finalSend[i] = udp_field[k];
    }
    for (i=8,k=0;i<finalSend.length && k< buffer.length;i++,k++)
    {
        finalSend[i] = buffer[k];
    }

    for (i=0;i<finalSend.length;i++)
    {
        System.out.println(finalSend[i]);
    }
    System.out.println("Got to final sending stage");
    DatagramPacket p = new DatagramPacket (finalSend,finalSend.length,InetAddress.getLocalHost(),7771);
    s.send(p);
    System.out.println("Sent datagram");

}

客户：

package simpleFTP;


public class SimpleFTPClient {



public static void main(String args[]) throws IOException{

     Integer seq_num =512;
     Utils u = new Utils();
     DatagramSocket d = new DatagramSocket();
     File f =new File("C:/Users/amoolp/Desktop/client3/3333.txt");
     FileInputStream fs = new FileInputStream(f);
     byte[] bytesRead = new byte[1024];
     fs.read(bytesRead,0,1024);

     //DatagramPacket p = new DatagramPacket (bytesRead,bytesRead.length,InetAddress.getLocalHost(),7771);
    // d.send(p);
     u.rdt_send(bytesRead,1024,d,seq_num);




}



}

服务器：

public class Server {

public static void main (String args[]) throws IOException
{
    DatagramSocket dg = new DatagramSocket (7771);

    byte[] buf = new byte[1032];
    DatagramPacket packet = new DatagramPacket(buf, buf.length);
    System.out.println("Waiting to receive packet");
    dg.receive(packet);
    System.out.println("Received packet");
    for (int i=0; i<buf.length ; i++)
    {
    System.out.println(buf[i]);
    }
    }

}

有关为何发生这种情况的任何想法？

Answer 1

这是由缓冲区造成的。发送数据包后刷新（）套接字。

UDP套接字发送和接收

1 个答案: