Sams Teach Yourself BEA WebLogic Server 7.0 in 21 Days - page 305

The code listing below illustrates this RMI client. You will first obtain the InitialContext object using "weblogic.jndi.WLInitialContextFactory" for the Context factory. After obtaining the IntialContext object, you will create the home object for your EJB by doing a lookup for it with its JNDI name and then performing a PortableRemoteObject.narrow() on this class. To test whether the object is properly obtained, you will perform a create on the WaiterHome object. To run the client, open a DOS session and include your EJB deployable file in the CLASSPATH of this session. Then run this Java client:

import java.io.PrintStream; 
import weblogic.utils.Debug;
import javax.naming.*;
import java.util.Hashtable;
import javax.rmi.*;

import com.sams.learnweblogic7.ejb.bmp.*;

public class EJBRMIClient {

  public final static String
          JNDI_FACTORY="weblogic.jndi.WLInitialContextFactory";
  static String url = "t3://localhost:7001";

  public EJBRMIClient() {}

  public static void main(String[] argv) throws Exception {
    try {
      InitialContext ctx = getInitialContext(url);
      Object home = ctx.lookup("Waiter_Home");
      WaiterHome myWaiterHome =
              (WaiterHome)PortableRemoteObject.narrow(home,
              WaiterHome.class);
      System.out.println(myWaiterHome.create());
    }
    catch (Throwable t) {
      t.printStackTrace();
      System.exit(-1);
    }
   }

  private static InitialContext getInitialContext(String url)
       throws NamingException
  {
    Hashtable env = new Hashtable();
    env.put(Context.INITIAL_CONTEXT_FACTORY, JNDI_FACTORY);
    env.put(Context.PROVIDER_URL, url);
    return new InitialContext(env);
  }
}

The following code demonstrates the answer to this exercise. The bean added to provide the functionality is called Invoice . The method findMaxInvoiceNo() uses WLQL and finds the maximum invoice number. Then the bean inserts a row into the database by incrementing the maximum number by one plus the price of the customer's bill.

In the Waiter Bean, only the getCheck() method has been changed, and hence only that method has been listed below. The ejb-jar.xml patch that is to be added to the existing ejb-jar.xml file and weblogic-cmp-rdbms-jar-invoice.xml file are also listed:

InvoiceHome.java 
package com.sams.learnweblogic7.ejb.cmp;

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

public interface InvoiceHome extends EJBHome
{
   public InvoiceInterface findByPrimaryKey(InvoicePK key)
      throws FinderException, RemoteException;

   public InvoiceInterface findMaxInvoiceNo()
      throws FinderException, RemoteException;

   InvoiceInterface create(int invoiceNo, long itemPrice)
      throws CreateException, RemoteException;
}

InvoiceInterface.java:

package com.sams.learnweblogic7.ejb.cmp; 

import javax.ejb.EJBObject;

import java.util.Vector;

import java.util.Date;
import java.rmi.RemoteException;

import java.sql.Time;

import java.sql.Date;

public interface InvoiceInterface extends EJBObject
{
   public int getInvoiceNo() throws RemoteException;
   public void setInvoiceNo(int invoiceNo) throws RemoteException;

   public long getItemPrice() throws RemoteException;
   public void setItemPrice(long itemPrice) throws RemoteException;
}

InvoiceBean.java:

package com.sams.learnweblogic7.ejb.cmp; 

import java.sql.Time;
import java.sql.Date;
import javax.ejb.EntityBean;
import javax.ejb.EntityContext;
import java.util.Vector;
import java.util.Date;

abstract public class InvoiceBean implements EntityBean
{
   /**
    * The container assigned reference to the entity
    */
   private EntityContext context;

   public InvoiceBean() {
   }

   /**
    * return invoiceNo
    */
   abstract public int getInvoiceNo();

   /**
    * param invoiceNo
    */
   abstract public void setInvoiceNo(int invoiceNo);

   /**
    * return itemPrice
    */
   abstract public long getItemPrice();

   /**
    * param itemPrice
    */
   abstract public void setItemPrice(long itemPrice);

   /**
    * Sets the context of the bean
    * param ec
    */
   public void setEntityContext(EntityContext ec) {
      context = ec;
   }

   /**
    * Clears the context of the bean
    */
   public void unsetEntityContext() {
      this.context = null;
   }

   public void ejbActivate() {
   }

   public void ejbPassivate() {
   }

   public void ejbLoad() {
   }

   public void ejbStore() {
   }

   /**
    *
    * param invoiceNo
    * param itemPrice
    */
   public InvoicePK ejbCreate(int invoiceNo, long itemPrice) {
      setInvoiceNo(invoiceNo);
      setItemPrice(itemPrice);
      return null;
   }

   /**
    * param invoiceNo
    * param itemPrice
    */
   public void ejbPostCreate(int invoiceNo, long itemPrice) {
   }

   public void ejbRemove() {
   }
}

InvoicePK:

package com.sams.learnweblogic7.ejb.cmp; 

import java.io.Serializable;
import java.sql.Date;

public class InvoicePK implements Serializable
{
   public int invoiceNo;

   public InvoicePK() {
   }

   /**
    * return hashcode
    */
   public int hashCode() {
      return (invoiceNo);
   }

   /**
    * return boolean
    */
   public boolean equals(Object that) {
      if (!(that instanceof InvoicePK))
         return false;
      else
         return true;
   }
}

WaiterBean.java:

//called by the client, to get his check. 
public float getCheck(){
   long checkSum = 0;
   try{
      InvoiceHome invHomeObj = lookupInvoiceHome();

      // this finder method demonstrates WEBLOGIC-QL
      InvoiceInterface invoiceObj = invHomeObj.findMaxInvoiceNo();
      int maxInvoiceNo = invoiceObj.getInvoiceNo();
      maxInvoiceNo = maxInvoiceNo + 1;

      Enumeration orderedItemsEnum = orderedItemsList.elements();
      while(orderedItemsEnum.hasMoreElements()){
         Order individualCurrOrder = (Order)orderedItemsEnum.nextElement();
         checkSum += (individualCurrOrder.getItem()).getItemPrice()*
                 individualCurrOrder.getQty();
      }

      InvoiceInterface displayInvoiceObject =
              (InvoiceInterface)PortableRemoteObject.narrow(invHomeObj.
              create(maxInvoiceNo , checkSum),InvoiceInterface.class);
      System.out.println("Invoice No := " + maxInvoiceNo);
   }
   catch(Exception e){
      e.printStackTrace();
   }
   return checkSum;
}

ejb-jar.xml:

<entity> 
   <ejb-name>InvoiceEJB</ejb-name>
   <home>com.sams.learnweblogic7.ejb.cmp.InvoiceHome</home>
   <remote>com.sams.learnweblogic7.ejb.cmp.InvoiceInterface</remote>
   <ejb-class>com.sams.learnweblogic7.ejb.cmp.InvoiceBean</ejb-class>
   <persistence-type>Container</persistence-type>
   <prim-key-class>com.sams.learnweblogic7.ejb.cmp.InvoicePK</prim-key-
           class>
   <reentrant>False</reentrant>
   <abstract-schema-name>Invoice</abstract-schema-name>
   <cmp-field>
      <field-name>invoiceNo</field-name>
   </cmp-field>
   <cmp-field>
      <field-name>itemPrice</field-name>
   </cmp-field>
   <query>
      <query-method>
         <method-name>findMaxInvoiceNo</method-name>
            <method-params>
            </method-params>
      </query-method>
      <ejb-ql>
         The query has been written in weblogic-cmp-rdbms-jar-invoice.xml
         since this is to demonstrate the use of weblogic-ql
      </ejb-ql>
   </query>
</entity>

weblogic-cmp-rdbms-jar-invoice:

<!DOCTYPE weblogic-rdbms-jar PUBLIC 
 '-//BEA Systems, Inc.//DTD WebLogic 6.0.0 EJB RDBMS Persistence//EN'
 'http://www.bea.com/servers/wls700/dtd/weblogic-rdbms20-persistence-
         700.dtd'>
 <weblogic-rdbms-jar>
    <weblogic-rdbms-bean>
       <ejb-name>InvoiceEJB</ejb-name>
       <data-source-name>ejb-datasource-learnweblogic7</data-source-name>
       <table-name>invoice</table-name>
       <field-map>
          <cmp-field>invoiceNo</cmp-field>
          <dbms-column>invoice_no</dbms-column>
       </field-map>
       <field-map>
          <cmp-field>itemPrice</cmp-field>
          <dbms-column>item_price</dbms-column>
       </field-map>
       <field-group>
          <group-name>invoiceGroup</group-name>
          <cmp-field>invoiceNo</cmp-field>
          <cmp-field>itemPrice</cmp-field>
       </field-group>
       <weblogic-query>
          <query-method>
             <method-name>findMaxInvoiceNo</method-name>
             <method-params>
             </method-params>
          </query-method>
          <weblogic-ql>
             <![CDATA[SELECT OBJECT(inv) FROM Invoice As inv
               WHERE inv.invoiceNo IN(SELECT MAX(inv2.invoiceNo) FROM
               Invoice AS inv2)]]>
          </weblogic-ql>
          <group-name>invoiceGroup</group-name>
          <!-- Use a group to specify that multi-media fields should not be
            read from the DB by this query. -->
          <max-elements>1000</max-elements>
          <include-updates>true</include-updates>
       </weblogic-query>
    </weblogic-rdbms-bean>
    <create-default-dbms-tables>True</create-default-dbms-tables>
</weblogic-rdbms-jar>

weblogic-ejb-jar.xml:

<weblogic-enterprise-bean> 
   <ejb-name>InvoiceEJB</ejb-name>
   <entity-descriptor>
      <persistence>
         <persistence-type>
            <type-identifier>WebLogic_CMP_RDBMS</type-identifier>
            <type-version>6.0</type-version>
            <type-storage>
               META-INF/weblogic-cmp-rdbms-jar-invoice.xml
            </type-storage>
         </persistence-type>
         <persistence-use>
            <type-identifier>WebLogic_CMP_RDBMS</type-identifier>
            <type-version>6.0</type-version>
         </persistence-use>
      </persistence>
   </entity-descriptor>
   <jndi-name>Invoice_Home</jndi-name>
</weblogic-enterprise-bean>