Simulate download using Java NiO

/**

* Fly_m at 2009-5-20

*/

Package com. m_ylf.study.nio;

 

Import java. Io. file;

Import java. Io. fileinputstream;

Import java.net. inetsocketaddress;

Import java. NiO. bytebuffer;

Import java. NiO. channels .*;

Import java. util. hashmap;

Import java. util. iterator;

Import java. util. Map;

Import java. util. Concurrent. callable;

 

/** @ Author fly_m */

// Simulate download service

Public class downloadserver <t> implements callable <t> {

Private selector; // create a global Selector

Private Map <socketchannel, handle> map = new hashmap <socketchannel, handle> (); // ing between socketchannel and handle

 

// Create a server serversocketchannel and register it with Selector

Public downloadserver () throws exception {

Selector = selector. open ();

Serversocketchannel = serversocketchannel. open ();

Serversocketchannel. configureblocking (false );

Serversocketchannel. socket (). BIND (New inetsocketaddress (1234 ));

Serversocketchannel. Register (selector, selectionkey. op_accept );

}

 

// Iterate selector. Select and process them in sequence

Public t call () throws exception {

System. Out. println ("startto listen in 1234 ....");

For (;{

Selector. Select ();

Iterator <selectionkey> keyiterator = selector. selectedkeys (). iterator ();

While (keyiterator. hasnext ()){

Selectionkey key = keyiterator. Next ();

If (key. isvalid ())

Handle (key );

Keyiterator. Remove ();

}

}

}

 

// Process each key. The primary class processes the acceptable key, and other events are processed by the internal class.

Private void handle (final selectionkey key) throws exception {

If (key. isacceptable ()){

Serversocketchannel channel = (serversocketchannel) Key. Channel ();

Socketchannel = channel. Accept ();

Socketchannel. configureblocking (false );

Socketchannel. Register (selector, selectionkey. op_read); // register a read event

Map. Put (socketchannel, new handle (); // bind the socket and handle.

}

// Use handle in map to process read and write events to simulate simultaneous download of multiple files

If (key. isreadable () | key. iswritable ()){

Socketchannel = (socketchannel) Key. Channel ();

Final handle = map. Get (socketchannel );

If (handle! = NULL)

Handle. Handle (key );

}

}

 

// Internal class. Simulate an internal class to process a file download service. Multiple classes can process multiple file download services.

Private class handle {

Private stringbuilder message;

Private Boolean writeok = true;

Private bytebuffer = bytebuffer. Allocate (1024 );

Private filechannel;

Private string filename;

 

Private void handle (selectionkey key) throws exception {

If (key. isreadable ()){

Socketchannel = (socketchannel) Key. Channel ();

If (writeok)

Message = new stringbuilder ();

While (true ){

Bytebuffer. Clear ();

Int r = socketchannel. Read (bytebuffer );

If (r = 0)

Break;

If (r =-1 ){

Socketchannel. Close ();

Key. Cancel ();

Return;

}

Message. append (new string (bytebuffer. Array (), 0, R ));

}

// Convert received information into a file name to map to a specified file on the server

If (writeok & invokemessage (Message )){

Socketchannel. Register (selector, selectionkey. op_write );

Writeok = false;

}

}

// Write data to the client

If (key. iswritable ()){

If (! Key. isvalid ())

Return;

Socketchannel = (socketchannel) Key. Channel ();

If (filechannel = NULL)

Filechannel = new fileinputstream (filename). getchannel ();

Bytebuffer. Clear ();

Int W = filechannel. Read (bytebuffer );

// If the file has been written, turn off the key and Socket

If (W <= 0 ){

Filename = NULL;

Filechannel. Close ();

Filechannel = NULL;

Writeok = true;

Socketchannel. Close ();

Key. Channel ();

Return;

}

Bytebuffer. Flip ();

Socketchannel. Write (bytebuffer );

}

}

 

// Convert the information into a file name

Private Boolean invokemessage (stringbuilder message ){

String M = message. tostring ();

Try {

File F = new file (m );

If (! F. exists ())

Return false;

Filename = m;

Return true;

} Catch (exception e ){

Return false;

}

}

 

}

 

Public static void main (string [] ARGs) throws exception {

/*

Executorservice = executors. newsinglethreadexecutor ();

Executorservice. Submit (New downloadserver <Object> ());

Executorservice. Shutdown ();

*/

New downloadserver (). Call ();

}

}

/*** Fly_m at 2009-5-20 */package COM. m_ylf.study.nio; import Java. io. randomaccessfile; import Java. NIO. bytebuffer; import Java. NIO. channels. filechannel; import Java. NIO. channels. selectionkey; import Java. NIO. channels. selector; import Java. NIO. channels. socketchannel; import Java. util. iterator; import Java. util. concurrent. callable; import Java. util. concurrent. executorservice; import Java. util. concurrent. exec Utors; import java.net. inetsocketaddress;/** @ author fly_m * // simulate the download of the public class downloadclient <t> implements callable <t> {private filechannel; Private Static selector; private bytebuffer = bytebuffer. allocate (1024); Private string serverfilename; // file private string localfilename on the server; // file name downloaded to the client public downloadclient (string serverfilename, string localfilename) {This. s Erverfilename = serverfilename; this. localfilename = localfilename;} public t call () throws exception {// enable selector and establish a socket connection to the specified port if (selector = NULL) selector = selector. open (); socketchannel channel = socketchannel. open (); channel. configureblocking (false); channel. connect (New inetsocketaddress ("localhost", 1234); channel. register (selector, selectionkey. op_connect); // read the information for (; {selector. select (); I Terator <selectionkey> keyiterator = selector. selectedkeys (). iterator (); While (keyiterator. hasnext () {selectionkey key = keyiterator. next (); keyiterator. remove (); // connection event if (key. isconnectable () {socketchannel = (socketchannel) Key. channel (); If (socketchannel. isconnectionpending () socketchannel. finishconnect (); socketchannel. write (bytebuffer. wrap (serverfilename. getbytes (); // sends a message to the server, which is a service in the information File Name of the socketchannel. register (selector, selectionkey. op_read);} // read event if (key. isreadable () {socketchannel = (socketchannel) Key. channel (); bytebuffer. clear (); If (! Socketchannel. isconnected () return NULL; // download the created file channelif (filechannel = NULL) filechannel = new randomaccessfile (localfilename, "RW") to the local machine "). getchannel (); int r = socketchannel. read (bytebuffer); // if the file is downloaded, turn off the channel and turn off socketchannelif (r <= 0) {If (filechannel! = NULL) filechannel. close (); channel. close (); key. cancel (); return NULL;} bytebuffer. flip (); // write it to filechannel In the downloaded file. write (bytebuffer) ;}}}// the client downloads files to the server using 10 threads and saves them as public static void main (string [] ARGs) of different files) throws exception {executorservice = executors. newsinglethreadexecutor (); For (INT I = 0; I <10; I ++) {executorservice. submit (New downloadclient <Object> ("D:/log4j. log "," d:/down "+ I + ". log ");} executorservice. shutdown ();}}