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J2EE™ Tutorial, The by Beth Stearns, Monica Pawlan, Eric Jendrock, Kim Haase, Dale Green, Stephanie Bodoff

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Primary Keys for Container-Managed Persistence

If the primary key class does not belong to the J2SE or J2EE standard libraries, then you must implement the class and package it along with the entity bean. For example, if your entity bean requires a composite primary key (which is made up of multiple fields), then you need to provide a customized primary key class.

The Primary Key Class

In the following example, the PurchaseOrderKey class implements a composite key for the PurchaseOrderEJB entity bean. The key is composed of two fields, productModel and vendorId, whose names must match two of the persistent fields in the entity bean class.

 public class PurchaseOrderKey implements java.io.Serializable { public String productModel; public String ...

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