Example - 1

The following Java example is a simple stateless Enterprise JavaBean that retrieves the interest rate for the number of points for a mortgage. In this example, the interest rates for various points are retrieved from an XML document on the local file system, and the EJB uses the Java I/O API to retrieve the XML document from the local file system.

// /* get XML document from the local filesystem */// 

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();DocumentBuilder db = dbf.newDocumentBuilder();interestRateXMLDocument = db.parse(interestRateFile);interestRateFile = new File(Constants.INTEREST_RATE_FILE);if (interestRateFile.exists()){}try {} catch (IOException ex) {...}
return getInterestRateFromXML(points);
// /* member function to retrieve interest rate from XML document on the local file system */// 
private Document interestRateXMLDocument = null;private File interestRateFile = null;public InterestRateBean() {}public BigDecimal getInterestRate(Integer points) {}private BigDecimal getInterestRateFromXML(Integer points) {...}@Statelesspublic class InterestRateBean implements InterestRateRemote {}

This use of the Java I/O API within any kind of Enterprise JavaBean violates the EJB specification by using the java.io package for accessing files within the local filesystem.

An Enterprise JavaBean should use a resource manager API for storing and accessing data. In the following example, the private member function getInterestRateFromXMLParser uses an XML parser API to retrieve the interest rates.

return getInterestRateFromXMLParser(points);
// /* member function to retrieve interest rate from XML document using an XML parser API */// 
public InterestRateBean() {}public BigDecimal getInterestRate(Integer points) {}private BigDecimal getInterestRateFromXMLParser(Integer points) {...}@Statelesspublic class InterestRateBean implements InterestRateRemote {}