countclient.java

为大家提供了《精通EJB》（第三版)一书的源代码

package examples;

import javax.ejb.*;
import javax.naming.*;
import java.util.Properties;

/**
 * This class is a simple example of client code.
 *
 * We create 3 EJB Objects in this example, but we only allow
 * the container to have 2 in memory.  This illustrates how
 * beans are passivated to storage.
 */
public class CountClient {

    public static final int noOfClients = 30;

    public static void main(String[] args) {
        
        try {
            /*
             * Get System properties for JNDI initialization
             */
            Properties props = System.getProperties();
            
            /*
             * Get a reference to the Home Object - the
             * factory for EJB Objects
             */
            Context ctx = new InitialContext(props);
            CountHome home = (CountHome)
                javax.rmi.PortableRemoteObject.narrow(
                                                      ctx.lookup("CountHome"), CountHome.class);
            
            /*
             * An array to hold the Count EJB Objects
             */
            Count count[] = new Count[noOfClients];
            
            int countVal = 0;
            
            /*
             * Create and count() on each member of array
             */
            System.out.println("Instantiating beans...");
            for (int i=0; i < noOfClients; i++) {
                /*
                 * Create an EJB Object and initialize
                 * it to the current count value.
                 */
                count[i] = home.create(countVal);
                
                /*
                 * Add 1 and print
                 */
                countVal = count[i].count();
                
                System.out.println(countVal);
                
                /*
                 * Sleep for 1/2 second
                 */
                Thread.sleep(100);
            }
            
            /*
             * Let's call count() on each EJB Object to
             * make sure the beans were passivated and
             * activated properly.
             */
            System.out.println("Calling count() on beans...");
            for (int i=0; i < noOfClients; i++) {
                
                /*
                 * Add 1 and print
                 */
                countVal = count[i].count();
                
                System.out.println(countVal);
                
                /*
                 * Sleep for 1/2 second
                 */
                Thread.sleep(100);
            }
            
            /*
             * Done with EJB Objects, so remove them 
             */
            for (int i=0; i < noOfClients; i++) {
                count[i].remove();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}