datapopulator.java

Oracle的J2EE Sample

 /*
 * @author  : Elangovan
 * @version : 1.0
 *
 * Development Environment : Oracle9i JDeveloper
 * Name of the File        : DataPopulator.java
 *
 * Creation / Modification History
 *    Elangovan           28-Aug-2003        Created
 *
 */
package oracle.otnsamples.ibfbs.admin.helper;

import java.util.ArrayList;
import java.util.Collection;

import oracle.toplink.tools.sessionmanagement.SessionManager;
import oracle.toplink.sessions.DatabaseSession;
import oracle.toplink.sessions.UnitOfWork;
import oracle.toplink.tools.sessionconfiguration.XMLLoader;
import oracle.toplink.threetier.ServerSession;
import oracle.toplink.threetier.ClientSession;
import oracle.toplink.exceptions.DatabaseException;
import oracle.toplink.tools.schemaframework.SchemaManager;

import oracle.otnsamples.ibfbs.toplink.News;

/**
 * This class creates the tables and sequences required by the FBS application.
 * Once the schema is created, it populates it with sample data. The schema is
 * created in the user specified in the data-source "jdbc/FBSDS".
 * 
 * @see SampleData.java
 * @see LoadDataServletCtxLsnr.java
 */
public class DataPopulator {

  // Toplink Server session handle
  private ServerSession server = null;
  
  /**
   * Creates a new instance of DataPopulator.
   */
  public DataPopulator() {    
  }

  /**
   * Initilizes the Server session.
   * 
   * @exception DatabaseException if intializing server session fails
   */
  private void initServerSession() 
    throws DatabaseException {
    // Initialize ServerSession from session.xml 
    try {
      // Get session details from session.xml
      server = (ServerSession) SessionManager.getManager().getSession(new XMLLoader(),
                                "FBSServerSession",
                                Thread.currentThread().getContextClassLoader());
                                
    } catch(DatabaseException dbEx) {
      System.err.println(" Fatal Error : Could not connect to database, check "+
                          " if you have provided proper values in "+
                          "<SAMPLE_HOME>/config/META-INF/data-sources.xml !!" );
      System.err.println(" Detailed Error : "+dbEx.toString());
      throw dbEx;
    }
  }

  /**
   * Creates the tables and sequences required by FBS application and populates 
   * them with sample data.
   * 
   * @exception DatabaseException if schema creation or population fails
   */
  public void populateSampleData() 
    throws DatabaseException {
        
    this.initServerSession();

    // Initialize Schema manager
    SchemaManager schemaManager = new SchemaManager((DatabaseSession) server);		
    
    // Check if data is already present
    if(!isDataLoaded()) {
      // Data not present
       
      // Create tables
      schemaManager.createObject(SampleData.getExchangeTableDefn());
      schemaManager.createObject(SampleData.getSymbolTableDefn());
      schemaManager.createObject(SampleData.getNewsTableDefn());
      schemaManager.createObject(SampleData.getStockrateTableDefn());
      
      // Create sequences
      schemaManager.createObject(SampleData.getOracleSequenceDefn("NEWS_SEQ",50,50));
      schemaManager.createObject(SampleData.getOracleSequenceDefn("PORTFOLIO_SEQ",1,1));
      schemaManager.createObject(SampleData.getOracleSequenceDefn("ALERTS_SEQ",1,1));
      schemaManager.createObject(SampleData.getOracleSequenceDefn("ACCOUNTNUMBER_SEQ",1,1));
      schemaManager.createObject(SampleData.getOracleSequenceDefn("TRADE_SEQ",1,1));
      schemaManager.createObject(SampleData.getOracleSequenceDefn("PREFERENCES_SEQ",1,1));
      
      // Populate data
      populateData();
    }   
  }
  
  /**
   * Checks if data is loaded in FBS schema.
   * 
   * @return  true - if data exists, false otherwise
   */
  private boolean isDataLoaded() {
    
    boolean loaded = false;
    
    try {            
      // Try to read a News object
      Object obj = server.readObject(News.class);
      if(obj != null) {
        // Success
        loaded=true;
      }        
    } catch(Exception ex) {   
      // Data not present 
      loaded = false;
    }
    return loaded;   
  }
  
  /**
   * Populate FBS schema with sample data.
   * 
   * @exception DatabaseException if populating sample data fails
   */
  private void populateData() 
    throws DatabaseException {
  
    // List to hold domain objects
    Collection data = new ArrayList();
    
    // Populate all data into 'data' Collection
    data.addAll(SampleData.populateExchange());
    data.addAll(SampleData.populateSymbol());    
    data.addAll(SampleData.populateStockRate());
    data.addAll(SampleData.populateStockNews());
    
    // Initialize client session 
    ClientSession client = server.acquireClientSession();    
    // Get a transaction
    UnitOfWork unitOfWork = client.acquireUnitOfWork();    
    // New or Updated objects have to be registered to get inserted/updated in datasource
    unitOfWork.registerAllObjects(data);
    // Commit
    unitOfWork.commit();
    
  }
  
}