Question

Reading the Tomcat 7 source code, I just wonder why Tomcat instance Catalina and invokes the related methods by using reflection instead of simply using new to create the object and calling the method directly?

Answer 1

The answer is in the javadoc comment of the Bootstrap class:

/**
 * Bootstrap loader for Catalina.  This application constructs a class loader
 * for use in loading the Catalina internal classes (by accumulating all of the
 * JAR files found in the "server" directory under "catalina.home"), and
 * starts the regular execution of the container.  The purpose of this
 * roundabout approach is to keep the Catalina internal classes (and any
 * other classes they depend on, such as an XML parser) out of the system
 * class path and therefore not visible to application level classes.
 *
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 * @version $Id: Bootstrap.java 1142323 2011-07-02 21:57:12Z markt $
 */

public final class Bootstrap { ... }