Threaded Java - Java - page 905

Discussion

The java.util.concurrent package includes Executors ; an Executor is, as its name im-
plies, a class that can execute code for you. The code to be executed can be the familiar Run-
nable or a new interface Callable . One common kind of Executor is a “thread pool.” The
code in Example 22-19 subclasses the main class of the Threaded Web Server from Program:
Threaded Network Server to use a pool of Threads to schedule multiple clients concurrently.

Example 22-19. HttpdConcurrent.java
/**
* HttpConcurrent - Httpd Subclass using java.lang.concurrent
*/
public public class class HttpdConcurrent HttpdConcurrent extends extends Httpd {

private private final final Executor myThreadPool ;

public public HttpdConcurrent () throws throws Exception {

super super ();

myThreadPool = Executors . newFixedThreadPool ( 5 );

}

public public static throws Exception {

System . out . println ( "DarwinSys JavaWeb Server 0.1 starting..." );
HttpdConcurrent w = new

static void void main ( String [] argv ) throws

new HttpdConcurrent ();
iif ( argv . length == 2 && argv [ 0 ]. equals ( "-p" )) {
w . startServer ( Integer . parseInt ( argv [ 1 ]));
} else else {

w . startServer ( HTTP );

}
w . runServer ();

}
public public void void runServer () throws throws Exception {

while while ( true true ) {

final final Socket clientSocket = sock . accept ();

myThreadPool . execute ( new

new Runnable () {

public public void void run () {

new new Handler ( HttpdConcurrent . this ). process ( clientSocket );

}

});

}

}

}

You can see this program in action in Figure 22-5 .