componentbean.java

EJB_原代码多例-好好东西啊

package com.wiley.compBooks.roman.session.fazuul;

import javax.ejb.*;
import java.util.*;
import java.rmi.*;

/**
 * Stateful Session Bean.
 */
public class ComponentBean implements SessionBean {

  // Constants used for reading properties object 
  public static final String ENV_MATCHES = "MATCHES";
  public static final String ENV_DESCRIPTION = "DESCRIPTION_";

  // Conversational state
  public String name;
  public String description;
  
  private transient SessionContext ctx;

  public void ejbCreate(String name) {
	this.name = name;

	/*
	 * Get the description of our Bean by querying the SessionContext
	 * and retrieving the application-specific properties.
	 */
	Properties props = ctx.getEnvironment();
	description = (String) props.get(ENV_DESCRIPTION + name);
  }
   
  public void ejbRemove() {
  }

  public void ejbActivate() {
  }

  public void ejbPassivate() {
  }

  public void setSessionContext(SessionContext ctx) {
	this.ctx = ctx;
  }

  /**
   * Attaches this component to another component.  If attach is successful,
   * the Bean will call remove() on the two EJB Objects, and generate a new,
   * combined Component.
   *
   * @return newly formed Component if successful
   * @exception ComponentException thrown if two Components can't fit together
   */
  public Component attachTo(Component other) throws RemoteException, ComponentException {

	/*
	 * Retrieve the application-specific environment properties from
	 * the current context.
	 */
	Properties props = ctx.getEnvironment();

	/*
	 * Get the list of matching components from the properties
	 */
	String matchString = (String) props.get(ENV_MATCHES);
	Enumeration matches = new StringTokenizer(matchString, ",");

	/*
	 * Loop through each match listing.  Match listings are of the form
	 * x+y=z, such as Snarf+Vrommell=Subbert.  Check to see if any of
	 * the matches involve our components.
	 */
	while (matches.hasMoreElements()) {
		String equationString = (String) matches.nextElement();

		Enumeration equation = new StringTokenizer(equationString, "+=");
		String nameA  = (String) equation.nextElement();
		String nameB  = (String) equation.nextElement();
		String result = (String) equation.nextElement();

		/*
		 * If there's a match, make the new, combined component
		 */
		if (  	  ( nameA.equals(this.getName())
			&&  nameB.equals(other.getName()) ) ||
			  ( nameB.equals(this.getName())
			&&  nameA.equals(other.getName()) ) ) {

			/*
			 * Get my Home Object from Session Context.
			 */
			ComponentHome home = (ComponentHome) ctx.getEJBHome();

			/*
			 * Create a new Component, and return it
			 */
			try {
				return home.create(result);
			}
			catch (Exception e) {
				throw new ComponentException(e.toString());
			}
		}
	}

	/*
	 * Two components don't fit together, so throw an exception
	 */
	throw new ComponentException("Those components do not fit together!");
  }

  /**
   * Returns the short name of this component
   */
  public String getName() throws RemoteException {
	return name;
  }

  /**
   * Returns the long description of this component
   */
  public String getDescription() throws RemoteException {
	return description;
  }
}