Writing Enterprise Applications with Java™ 2 SDK, Enterprise Edition phần 8 ppt

LESSON 5 ADDING JAVABEANS TECHNOLOGY TO THE MIX

83 SEPTEMBER 27, 2000

Getter methods follow the same naming conventions as setter methods so the JSP page can

retrieve data from the JBonusBean.Getter methods always have a return value and no argu￾ments. You might notice that although the getBonusAmt method sets property values and

does not really need to return a value in this example, it returns this.bonusAmt to avoid a

runtime J2EE server error.

The getBonusAmt method uses an if-else statement to handle the case where no strMult

value is supplied. When the JSP page is first loaded, the end user has not supplied any data,

but all tags and scriptlets on the page are executed anyway. In this event, the data value for

the strMult property passed to JBonusBean is null, which results in a null multiplier and a

null bonusAmt value. A runtime server error occurs when the JSP page gets and tries to dis￾play the null bonusAmt value. To prevent this runtime error, bonusAmt is set to 0 in the event

a null strMult value is received from the JSP page.

public double getBonusAmt() {

if(strMult != null){

Integer integerMult = new Integer(strMult);

int multiplier = integerMult.intValue();

try {

double bonus = 100.00;

Calc theCalculation = homecalc.create();

Bonus theBonus = theCalculation.calcBonus(

multiplier, bonus, socsec);

Bonus record = theCalculation.getRecord(

socsec);

bonusAmt = record.getBonus();

socsec = record.getSocSec();

} catch (javax.ejb.DuplicateKeyException e) {

message = e.getMessage();

} catch (javax.ejb.CreateException e) {

e.printStackTrace();

} catch (java.rmi.RemoteException e) {

e.printStackTrace();

}

return this.bonusAmt;

} else {

this.bonusAmt = 0;

this.message = "None.";

return this.bonusAmt;

}

}

public String getMessage(){