accountbean.java

EJB_原代码多例-好好东西啊

package com.wiley.compBooks.roman.entity.account;

import java.sql.*;
import javax.naming.*;
import javax.ejb.*;
import java.util.*;
import java.rmi.RemoteException;


/**
 * Demonstration Bean-Managed Persistent Entity Bean.
 * This Entity Bean represents a Bank Account.
 */
public class AccountBean implements EntityBean {

	protected EntityContext ctx;

	// Bean-managed state fields
	public String accountID;	// PK
	public String ownerName;
	public double balance;

	// Environment properties the bean was deployed with
	public Properties env;

	public AccountBean() {
		System.out.println("New Bank Account Entity Bean Java Object created by EJB Container.");
	}

	//
	// Business Logic Methods
	//

	/**
	 * Deposits amt into account.
	 */
	public void deposit(double amt) throws AccountException {
		System.out.println("deposit(" + amt + ") called.");
		
		balance += amt;
	}

	/**
	 * Withdraws amt from bank account.
	 * @throw AccountException thrown in amt < available balance
	 */
	public void withdraw(double amt) throws AccountException {
		System.out.println("withdraw(" + amt + ") called.");

		if (amt > balance) {
			throw new AccountException("Your balance is " + balance + "!  You cannot withdraw " + amt + "!");
		}

		balance -= amt;
	}

	// Getter/setter methods on Entity Bean fields

	public double getBalance() {
		System.out.println("getBalance() called.");
		return balance;
	}

	public void setOwnerName(String name) {
		System.out.println("setOwnerName() called.");
		ownerName = name;
	}
	
	public String getOwnerName() {
		System.out.println("getOwnerName() called.");
		return ownerName;
	}
	
	public String getAccountID() {
		System.out.println("getAccountID() called.");
		return accountID;
	}
	
	public void setAccountID(String id) {
		System.out.println("setAccountID() called.");
		this.accountID = id;
	}
	
	//
	// EJB-required methods
	//

	/**
	 * Called by Container.  Implementation can acquire
	 * needed resources.
	 */
	public void ejbActivate() throws RemoteException {
		System.out.println("ejbActivate() called.");
	}

	/**
	 * Removes entity bean data from the database.
	 * Corresponds to when client calls home.remove().
	 */
	public void ejbRemove() throws RemoteException {
		System.out.println("ejbRemove() called.");

		/*
		 * Remember that an entity bean class can be used to
		 * represent different data instances.  So how does
		 * this method know which instance in the database
		 * to delete?
		 *
		 * The answer is to query the container by calling
		 * the entity context object.  By retrieving the
		 * primary key from the entity context, we know
		 * which data instance, keyed by the PK, that we
		 * should delete from the DB.
		 */
                AccountPK pk = (AccountPK) ctx.getPrimaryKey();
                String id = pk.accountID;

                PreparedStatement pstmt = null;
                Connection conn = null;
                try {
                        /*
			 * 1) Acquire a new JDBC Connection
			 */
                        conn = getConnection();

                        /*
			 * 2) Remove account from the DB
			 */
                        pstmt = conn.prepareStatement("delete from accounts where id = ?");
                        pstmt.setString(1, id);
			
			/*
			 * 3) Throw a system-level exception if something
			 * bad happened.
			 */
			if (pstmt.executeUpdate() == 0) {
                	        throw new RemoteException("Account " + pk + " failed to be removed from the database");
			}
                }
                catch (SQLException ex) {
			throw new RemoteException(ex.toString());
                }
                finally {
                        /*
			 * 4) Release the DB Connection
			 */
                        try {
                                if (pstmt != null) pstmt.close();
			}
			catch (Exception e) { }
			try {
                                if (conn != null) conn.close();
                        }
                        catch (Exception e) { }
                }
	}

	/**
	 * Called by Container.  Releases held resources for
	 * passivation.
	 */
	public void ejbPassivate() throws RemoteException {
		System.out.println("ejbPassivate () called.");
	}

	/**
	 * Called by the container.  Updates the in-memory entity
	 * bean object to reflect the current value stored in
	 * the database.
	 */
	public void ejbLoad() throws RemoteException {
		System.out.println("ejbLoad() called.");

		/*
		 * Again, query the Entity Context to get the current
		 * Primary Key, so we know which instance to load.
		 */
		AccountPK pk = (AccountPK) ctx.getPrimaryKey();
		String id = pk.accountID;

		PreparedStatement pstmt = null;
                Connection conn = null;
		try {
			/*
			 * 1) Acquire a new DB Connection
			 */
			conn = getConnection();

			/*
			 * 2) Get account from the DB, querying
			 *    by account ID
			 */
			pstmt = conn.prepareStatement("select ownerName, balance from accounts where id = ?");
			pstmt.setString(1, id);
			ResultSet rs = pstmt.executeQuery();
			rs.next();
			ownerName = rs.getString("ownerName");
			balance = rs.getDouble("balance");
		}
		catch (SQLException ex) {
			throw new RemoteException("Account " + pk + " failed to load from database", ex);
		}
		finally {
			/*
			 * 3) Release the DB Connection
			 */
			try {
				if (pstmt != null) pstmt.close();
			}
			catch (Exception e) { }
			try {
				if (conn != null) conn.close();
			}
			catch (Exception e) { }
		}

	}

	/**
	 * Called from the Container.  Updates the database
	 * to reflect the current values of this in-memory
	 * entity bean instance.
	 */
	public void ejbStore() throws RemoteException {
		System.out.println("ejbStore() called.");

		PreparedStatement pstmt = null;
                Connection conn = null;
		try {
			/*
			 * 1) Acquire a new DB Connection
			 */
			conn = getConnection();

			/*
			 * 2) Store account in DB
			 */
			pstmt = conn.prepareStatement("update accounts set ownerName = ?, balance = ? where id = ?");
			pstmt.setString(1, ownerName);
			pstmt.setDouble(2, balance);
			pstmt.setString(3, accountID);
			pstmt.executeUpdate();

		}
		catch (SQLException ex) {
			throw new RemoteException("Account " + accountID + " failed to save to database", ex);
		}
		finally {
			/*
			 * 3) Release the DB Connection
			 */
			try {
				if (pstmt != null) pstmt.close();
			}
			catch (Exception e) { }
			try {
				if (conn != null) conn.close();
			}
			catch (Exception e) { }
		}
	}

	/**
	 * Called by the container.  Associates this bean
	 * instance with a particular context.  We can query
	 * the bean properties which customize the bean here.
	 */
	public void setEntityContext(EntityContext ctx) throws RemoteException {
		System.out.println("setEntityContext called");
		this.ctx = ctx;

		env = ctx.getEnvironment();
	}

	/**
	 * Called by Container.  Disassociates this bean
	 * instance with a particular context environment.
	 */
	public void unsetEntityContext() throws RemoteException {
		System.out.println("unsetEntityContext called");
		this.ctx = null; 
		this.env = null;
	}

	/**
	 * Called after ejbCreate().  Now, the Bean can retrieve
	 * its EJBObject from its context, and pass it as
	 * a 'this' argument.
	 */
	public void ejbPostCreate(String accountID, String ownerName) throws RemoteException {
	}

	/**
	 * This is the initialization method that corresponds to the
	 * create() method in the Home Interface.
	 *
	 * When the client calls the Home Object's create() method,
	 * the Home Object then calls this ejbCreate() method.
	 *
	 * @return The primary key for this account
	 */
	public AccountPK ejbCreate(String accountID, String ownerName) throws CreateException, RemoteException {

	  PreparedStatement pstmt = null;
	  Connection conn = null;
	  try {
		System.out.println("ejbCreate() called.");
		this.accountID = accountID;
		this.ownerName = ownerName;
		this.balance = 0;

		/*
		 * Acquire DB connection
		 */
		conn = getConnection();
	
		/*
		 * Insert the account into the database
		 */
		pstmt = conn.prepareStatement("insert into accounts (id, ownerName, balance) values (?, ?, ?)");
		pstmt.setString(1, accountID);
		pstmt.setString(2, ownerName);
		pstmt.setDouble(3, balance);
		pstmt.executeUpdate();

		/*
		 * Generate the Primary Key and return it
		 */
		return new AccountPK(accountID);
	  }
	  catch (Exception e) {
		throw new CreateException(e.toString());
	  }
	  finally {
		/*
		 * Release DB Connection for other beans
		 */
		try {
			pstmt.close();
		}
		catch (Exception e) { }
		try {
			conn.close();
		}
		catch (Exception e) { }
	  }
	}

	/**
	 * Finds a Account by its primary Key
	 */
	public AccountPK ejbFindByPrimaryKey(AccountPK key) throws FinderException, RemoteException {
	  PreparedStatement pstmt = null;
          Connection conn = null;
	  try {
		System.out.println("ejbFindByPrimaryKey(" + key + ") called");

		/*
		 * Acquire DB connection
		 */
		conn = getConnection();
		
		/*
		 * Find the Entity in the DB
		 */
		pstmt = conn.prepareStatement("select id from accounts where id = ?");
		pstmt.setString(1, key.toString());
		ResultSet rs = pstmt.executeQuery();
		rs.next();
		
		/*
		 * No errors occurred, so return the Primary Key
		 */
		return key;
	  }
	  catch (Exception e) {
		throw new FinderException(e.toString());
	  }
	  finally {
		/*
		 * Release DB Connection for other beans
		 */
		try {
			pstmt.close();
		}
		catch (Exception e) { }
		try {
			conn.close();
		}
		catch (Exception e) { }
	  }
	}

	/**
	 * Finds a Account by its Name
	 */
	public Enumeration ejbFindByOwnerName(String name) throws FinderException, RemoteException {
	  PreparedStatement pstmt = null;
	  Connection conn = null;
	  Vector v = new Vector();

	  try {
		System.out.println("ejbFindByOwnerName(" + name + ") called");
		
		/*
		 * Acquire DB connection
		 */
		conn = getConnection();
		
		/*
		 * Find the primary keys in the DB
		 */
		pstmt = conn.prepareStatement("select id from accounts where ownerName = ?");
		pstmt.setString(1, name);
		ResultSet rs = pstmt.executeQuery();

		/*
		 * Insert every primary key found into a vector
		 */
		while (rs.next()) {
			String id = rs.getString("id");
			v.addElement(new AccountPK(id));
		}
		
		/*
		 * Return an enumeration of found primary keys
		 */
		return v.elements();
	  }
	  catch (Exception e) {
		throw new FinderException(e.toString());
	  }
	  finally {
		/*
		 * Release DB Connection for other beans
		 */
		try {
			pstmt.close();
		}
		catch (Exception e) { }
		try {
			conn.close();
		}
		catch (Exception e) { }
	  }
	}

	public static final String JDBC_URL = "JDBC_URL";
	
	/**
	 * Gets current connection to the connection pool.
	 *
	 * Note: In the future, once vendors have adopted JDBC 2.0,
	 * the preferred method for retrieving a JDBC Connection is
	 * through JNDI.
	 *
	 * Assumes that environment properties contains a property
	 * named "user" and "password" if authentication is desired.
	 * These environment properties are retrieved from the
	 * EntityContext object during setEntityContext().
	 *
	 * @return                  Connection
	 * @exception               java.sql.SQLException
	 *
	 */
	public Connection getConnection() throws SQLException {
		String jdbcURL = (String) env.get(JDBC_URL);
	
		// For debugging...	
		// String drivers = (String) env.get("jdbc.drivers");
		// System.out.println(jdbcURL + ", " + drivers);
		// DriverManager.setLogStream(System.out);
	
		return DriverManager.getConnection(jdbcURL, env);
	}

//	static {
//		try {	
//			new weblogic.jdbc.jts.Driver();
//			Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
//		}
//		catch (Exception e) {
//			e.printStackTrace();
//		}
//	}
}