Java Network Programming Summary 1

1. Basic TCP network programming mode
The first is the server. The server uses serversocket,

 

Import java.net .*;
Import java. Io .*;

Public class tcpserver {
Public static void main (string [] ARGs) throws exception {
Serversocket Ss = new serversocket (6666 );
While (true ){

Socket S = ss. Accept ();

Datainputstream Dis = new datainputstream (S. getinputstream ());

System. Out. println (DIS. readutf ());
Dis. Close ();
S. Close ();
}
}
}

 

Client

Import java.net .*;
Import java. Io .*;

Public class tcpclient {
Public static void main (string [] ARGs) throws exception {
Socket S = new socket ("127.0.0.1", 6666 );
Outputstream OS = S. getoutputstream ();
Dataoutputstream dos = new dataoutputstream (OS );
Thread. Sleep (30000 );
Dos. writeutf ("Hello server! ");
Dos. Flush ();
Dos. Close ();
S. Close ();
}
}

For the client, the output is sent to the server.

 

2Program, You can output the client's IP port to the client through the server.

Import java.net .*;
Import java. Io .*;

Public class testserver {
Public static void main (string ARGs []) {
Try {
Serversocket S = new serversocket (8888 );
While (true ){
Socket S1 = S. Accept ();
Outputstream OS = s1.getoutputstream ();
Dataoutputstream dos = new dataoutputstream (OS );
Dos. writeutf ("hello," + s1.getinetaddress () +
"Port #" + s1.getport () + "bye-bye! ");
Dos. Close ();
S1.close ();
}
} Catch (ioexception e ){
E. printstacktrace ();
System. Out. println ("program running error:" + E );
}
}
}

 

The client displays the information entered by the server.

Import java.net .*;
Import java. Io .*;

Public class testclient {
Public static void main (string ARGs []) {
Try {
Socket S1 = new socket ("127.0.0.1", 8888 );
Inputstream is = s1.getinputstream ();
Datainputstream Dis = new datainputstream (is );
System. Out. println (DIS. readutf ());
Dis. Close ();
S1.close ();
} Catch (connectexception connexc ){
Connexc. printstacktrace ();
System. Err. println ("server connection failed! ");
} Catch (ioexception e ){
E. printstacktrace ();
}
}
}

 

 

3. The following TCP message is sent by the customer and the server to each other.
Server:
Import java. Io .*;
Import java.net .*;
Public class testsockserver {
Public static void main (string [] ARGs ){
Inputstream in = NULL;
Outputstream out = NULL;
Try {
Serversocket Ss = new serversocket (5888 );
Socket socket = ss. Accept ();
In = socket. getinputstream ();
Out = socket. getoutputstream ();
Dataoutputstream dos = new dataoutputstream (out );
Datainputstream Dis = new datainputstream (in );
String S = NULL;
If (S = dis. readutf ())! = NULL ){
System. Out. println (s );
System. Out. println ("from:" + socket. getinetaddress ());
System. Out. println ("port:" + socket. getport ());
}
Dos. writeutf ("hi, hello ");
Dis. Close ();
Dos. Close ();
Socket. Close ();
} Catch (ioexception e) {e. printstacktrace ();}
}
}

Client:
Import java.net .*;
Import java. Io .*;
Public class testsockclient {
Public static void main (string [] ARGs ){
Inputstream is = NULL; outputstream OS = NULL;
Try {
Socket socket = new socket ("localhost", 5888 );
Is = socket. getinputstream ();
OS = socket. getoutputstream ();
Datainputstream Dis = new datainputstream (is );
Dataoutputstream dos = new dataoutputstream (OS );
Dos. writeutf ("hey ");
String S = NULL;
If (S = dis. readutf ())! = NULL );
System. Out. println (s );
Dos. Close ();
Dis. Close ();
Socket. Close ();
} Catch (unknownhostexception e ){
E. printstacktrace ();
} Catch (ioexception e) {e. printstacktrace ();}
}
}

5 In UDP, pay attention to the application of mongorampacket. The following is the message sent from the client to the server.
Public class testudpclient
{
Public static void main (string ARGs []) throws exception
{
Byte [] Buf = (new string ("hello"). getbytes ();

Datagrampacket dp = new datagrampacket (BUF, Buf. length,
New inetsocketaddress ("Wagner. 0.0.1", 5678)
);
Datagramsocket DS = new datagramsocket (9999 );
DS. Send (DP );
DS. Close ();
}

Server:

Import java.net .*;

Public class testudpserver
{
Public static void main (string ARGs []) throws exception
{
Byte Buf [] = new byte [1024];
Datagrampacket dp = new datagrampacket (BUF, Buf. Length );
Datagramsocket DS = new datagramsocket (5678 );
While (true)
{
DS. Receive (DP );
System. Out. println (new string (BUF, 0, DP. getlength ()));
}
}
}

Note that if it is other types of data on the client, you should pay attention to the conversion. For example, the following example transfers a long integer to the server:
Client:
Public class testudpclient
{
Public static void main (string ARGs []) throws exception
{
Long n = 10000l;
Bytearrayoutputstream baos = new bytearrayoutputstream ();
Dataoutputstream dos = new dataoutputstream (baos );
Dos. writelong (N );

Byte [] Buf = baos. tobytearray ();
System. Out. println (BUF. Length );

Datagrampacket dp = new datagrampacket (BUF, Buf. length,
New inetsocketaddress ("Wagner. 0.0.1", 5678)
);
Datagramsocket DS = new datagramsocket (9999 );
DS. Send (DP );
DS. Close ();

}
}

Server:

Import java.net .*;
Import java. Io .*;

Public class testudpserver
{
Public static void main (string ARGs []) throws exception
{
Byte Buf [] = new byte [1024];
Datagrampacket dp = new datagrampacket (BUF, Buf. Length );
Datagramsocket DS = new datagramsocket (5678 );
While (true)
{
DS. Receive (DP );
Bytearrayinputstream BAIS = new bytearrayinputstream (BUF );
Datainputstream Dis = new datainputstream (BAIS );
System. Out. println (DIS. readlong ());
}
}
}