Server-Side Java - Java - page 659

Solution

Create a ServerSocket and write some code that “speaks” the particular protocol. Or, better,
use a Java-powered web server such as Apache Tomcat or a Java Enterprise Edition (Java
EE) server such as JBoss WildFly.

Discussion

You can implement your own HTTP protocol server for very simple applications, which
we'll do here. For any serious development, you want to use the Java Enterprise Edition; see
the note at the beginning of this chapter.

This example just constructs a ServerSocket and listens on it. When connections come in,
they are replied to using the HTTP protocol. So it is somewhat more involved than the
simple Echo server presented in Returning a Response (String or Binary) . However, it's not a
complete web server; the filename in the request is ignored, and a standard message is al-
ways returned. This is thus a very simple web server; it follows only the bare minimum of
the HTTP protocol needed to send its response back. A somewhat more complete example is
presented in Program: Threaded Network Server , after the issues of multithreading have been
covered. For a real web server written in Java, get Tomcat from the Apache Tomcat website .
The code shown in Example 16-8 , however, is enough to understand how to structure a
simple server that communicates using a protocol.

Example 16-8. WebServer0.java
public

public class class WebServer0 WebServer0 {

public public static static final final int int HTTP = 80 ;

public public static final String CRLF = "\r\n" ;

ServerSocket s ;
static

static final

static final final String VIEW_SOURCE_URL =

"https://github.com/IanDarwin/javasrc/tree/master/src/main/java/network" ;

/**
* Main method, just creates a server and call its runServer().
*/
public public static throws Exception {

System . out . println ( "DarwinSys JavaWeb Server 0.0 starting..." );
WebServer0 w = new

static void void main ( String [] argv ) throws

new WebServer0 ();
w . runServer ( HTTP ); // never returns!!

}

/** Get the actual ServerSocket; deferred until after Constructor
* so subclass can mess with ServerSocketFactory (e.g., to do SSL).