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Developing EJB by WSAD
Prerequisite:
1. WSAD 402
2. DB2/UDB 7.2.1 or greater version
3. Has DB2 sample database created
Part One: Creat a new EJB Project
1. Perspective -> Open -> Other -> J2EE Perspective.
2. File -> New -> EJB Project
Project Name: AccountAndTransferEJBModule
EAR Project: AccountAndTransferEAR
Next -> Next -> Finish
Verify:
J2EE Perspective -> J2EE View
EJB Modules -> AccountAndTransferEJBModule
Enterprise Applications -> AccountAndTransferEAR
Part Two: Creating a CMP entity bean
1. Create a CMP
File -> New -> Enterprise Bean
Bean Name: Account
EJB Project: AccountAndTransferEJBModule
Source folder: ejbModule
Default package: com.ibm.wsad.spc
-> Next
Bean supertype: <none>
Bean class: com.ibm.wsad.spc.AccountBean
Home interface: com.ibm.wsad.spc.AccountHome
Remote interface: com.ibm.wsad.spc.Account
Key class: com.ibm.wsad.spc.AccountKey
CMP attributes:
1). accountId: long (key field)
2). type: int
3). balance: float
-> Next
import javax.ejb.*
-> Finish
Verify:
J2EE Perspective-> J2EE View
EJB Modules -> AccountAndTransferEJBModule -> Account
2. Create a custom exception
File -> New -> Other -> Java -> Java Class.
Folder: /AccountAndTransferEJBModule/ejbModule
Package: com.ibm.wsad.spc
Name: InsufficientFundsException
Superclass: java.lang.Exception
Check "Constructor from superclass"
-> Finish
3. Add two methods to AccountBean.java
/* adds the specified amount to the account balance and returns
* the new balance
*/
public float add(float amount) {
balance += amount;
return balance;
}
/* subtracts the specified amount from the account balance and
* returns the new balance
*/
public float subtract(float amount) throws InsufficientFundsException {
if (balance < amount) {
throw new InsufficientFundsException("Insufficient funds");
}
balance -= amount;
return balance;
}
4. Add these two methods to Remote Interface
Double Click J2EE Perspective -> J2EE View -> EJB Modules -> AccountAndTransferEJBModule -> Account -> AccountBean
Outline view
Right mouse click add(float) -> Promote to Remote Interface
Right mouse click substract(float) -> Promote to Remote Interface
Verify:
J2EE Perspective -> J2EE View -> EJB Modules -> AccountAndTransferEJBModule -> Account -> Account
/* adds the specified amount to the account balance and returns
* the new balance
*/
public float add(float amount) throws java.rmi.RemoteException;
/* subtracts the specified amount from the account balance and
* returns the new balance
*/
public float subtract(float amount) throws InsufficientFundsException, java.rmi.RemoteException;
5. Create Top Down EJB/RDB Mapping
J2EE Perspective -> Navigator View
Right-click AccountAndTransferEJBModule
Generate -> EJB to RDB maping
Select Top Down way to build EJB to RDB maping
Verify:
J2EE Perspective -> Navigator View
Schema.dbxmi and Map.mapxmi are both created
Double click Map.mapxmi
6. Create A Database Table
Drag and drop Table.ddl out into a directory, eg: C:\temp
Start -> Run -> db2cmd
db2 connect to SAMPLE use db2admin using db2admin
db2 list tables for all
db2 -tf C:\temp\Table.ddl
db2 insert into db2admin.account(accountid, type, balance) values(1, 1, 15.15)
db2 insert into db2admin.account(accountid, type, balance) values(2, 1, 30.15)
db2 select * from db2admin.account
7. Define a Datasource name for our CMP
J2EE Perspective -> Navigator View -> AccountAndTransferEJBModule -> META-INF
Right mouse click ejb-jar.xml, Open with -> EJB Extension Editor
Select "Bindings" tab
JNDI Name: Account
Datasource JNDI Name: jdbc/SAMPLE
Default use id: db2admin
Default password: ************
//note: "Ctrl + S" to save the change
8. Define a Datasource to our Server Environment
Open a Server Perspective
File -> New -> Project -> Server Project
Project Name: SPC1
-> Finish
File -> New -> Server Instance and Configuration
Server Name: WASSVR1
In "Server Configuration" window, Double click WASSVR1
Select "Data source" tab
Mark "COM.ibm.db2.jdbc.DB2ConnectionPoolDataSource" in JDBC driver list
Add a Datasource defined in the JDBC driver select above
Close WASSVR1 editor window
Server Perspective -> Server Configuration window -> Server Configurations
right mouse click WASSVR1
Add Project -> AccountTransferEAR
Verify:
J2EE Perspective -> Navigator View
Right mouse click AccountTransferEJBModule
Select Properties -> Server Preference
10. Genegrate Deployed Code
J2EE Perspective -> J2EE View -> EJBModules
Right mouse click AccountAndTransferEJBModule
Generate -> Deploy code and RMIC Stub and Tie code
-> Finish
Part3: Test CMP Bean
1. Server Perspective -> Navigator View
Right mouse click AccountAndTransferEJBModule
Select Run on Server
IBM EJB Test Client
JNDI Explorer
Click Account
Click Account findByPrimaryKey(AccountKey)
Invoke and Return
Invoke
Click Work with Object
float getBalance() 15.15
void setBalance(float) 12.15
Start -> Run -> db2cmd
db2 connect to sample user db2admin using db2admin
db2 select * from Account
C:\>db2 select * from account
ACCOUNTID TYPE BALANCE
-------------------- ----------- ------------------------
1 1 +1.21500E+001
2 1 +3.01500E+001
2 record(s) selected.
2. Stop Server
Close EBJ Test Client window
Server Perspective -> Servers View -> Server tab
Right mouse click WASSVR1 -> Stop
Part 4: Create Transfer Stateless Session EJB
1. J2EE Perspective -> J2EE View
File -> New -> Enterprise Beans
-> Next -> Next
-> Finish
Open TransferBean.java
Add the following field and methods:
private AccountHome accountHome = null;
/**
* Returns the balance of the account identified by the acctId
* parameter
*/
public float getBalance(long acctId) throws javax.ejb.FinderException {
AccountKey key = new AccountKey(acctId);
Account fromAccount;
try {
fromAccount = accountHome.findByPrimaryKey(key);
return fromAccount.getBalance();
} catch (FinderException ex) {
throw new FinderException("Account " + acctId + "does not exist");
} catch (RemoteException ex) {
throw new EJBException("Cannot get balance for " + acctId);
}
}
/**
* Transfers the specified amount from the fromAcctId account
* to the toAcctId account; throws InsufficientFundsException
* if the account identified by the fromAcctId contains less
* than the amount requested for tranfer.
*/
public void transferFunds(long fromAcctId, long toAcctId, float amount)
throws InsufficientFundsException, javax.ejb.FinderException {
AccountKey fromKey = new AccountKey(fromAcctId);
AccountKey toKey = new AccountKey(toAcctId);
Account fromAccount, toAccount;
try {
fromAccount = accountHome.findByPrimaryKey(fromKey);
toAccount = accountHome.findByPrimaryKey(toKey);
toAccount.add(amount);
fromAccount.subtract(amount);
} catch (FinderException ex) {
throw new FinderException("Account " + fromAcctId + " does not exist.");
} catch (RemoteException ex) {
throw new EJBException();
} catch (InsufficientFundsException ex) {
mySessionCtx.setRollbackOnly();
throw new InsufficientFundsException("Insufficient funds in " + fromAcctId);
}
}
/**
* Gets the home object for the CMP Account EJB using ejb
* references. This method returns a reference to the
* AccountHome object when the bean is being created.
*/
public AccountHome getHome() {
try {
InitialContext initCtx = new InitialContext();
Object objref = initCtx.lookup("Account");
return (AccountHome) PortableRemoteObject.narrow(objref, AccountHome.class);
} catch (NamingException ne) {
ne.printStackTrace();
throw new EJBException(
"Error looking up AccountHome object: " + ne.getMessage());
}
}
Add code into ejbCreate() of TransferBean.java
accountHome = getHome();
2. Promote getBalance and transferFunds to EJB Remote Interface
Part 5: Test Both EJBs
1. Regenerate the deployed code
J2EE Perspective -> J2EE View -> EJB Modules
Right mouse click AccountAndTransferEJBModule
Select Generate -> Deploy code and RMIC Stub and Tie code
2. Start Server
J2EE Perspective -> Navigator View
Right mouse click AccountAndTransferEJBModule
-> Run On Server
Transfer
Transfer create()
Invoke
Work with Object
float getBalance()
Invoke
void transferFunds(long, long, float)
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