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Bean Validation support generate, create qr codes none for software projects .NET CF Another new feature introduce qr-codes for None d in JPA 2.0 is support for JSR 303, Bean Validation. Bean Validation support allows us to annotate our JPA entities with Bean Validation annotations.

These annotations allow us to easily validate user input and perform data sanitation.. [ 199 ]. Database Connectivity Taking advantage of Bean Vali dation is very simple, all we need to do is annotate our JPA entity fields or getter methods with any of the validation annotations defined in the javax.validation.constraints package.

Once our fields are annotated as appropriate, the EntityManager will prevent non-validating data from being persisted. The following code example is a modified version of the Customer JPA entity we saw earlier in this chapter. It has been modified to take advantage of Bean Validation in some of its fields.

. package net.ensode.glassfishb Software Quick Response Code ook.

jpa.beanvalidation; import java.io.

Serializable; import import import import import import javax.persistence.Column; javax.

persistence.Entity; javax.persistence.

Id; javax.persistence.Table; javax.

validation.constraints.NotNull; javax.

validation.constraints.Size;.

@Entity @Table(name = "CUSTOM ERS") public class Customer implements Serializable { @Id @Column(name = "CUSTOMER_ID") private Long customerId; @Column(name = "FIRST_NAME") @NotNull @Size(min=2, max=20) private String firstName; @Column(name = "LAST_NAME") @NotNull @Size(min=2, max=20) private String lastName; private String email; public Long getCustomerId() { return customerId; [ 200 ]. 5 } public void setCustomerI Software Denso QR Bar Code d(Long customerId) { this.customerId = customerId; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.

firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } }. In this example, we used the @NotNull annotation to prevent the firstName and lastName of our entity from being persisted with null values. We also used the @Size annotation to restrict the minimum and maximum length of these fields. This is all we need to do to take advantage of Bean Validation in JPA.

If our code attempts to persist or update an instance of our entity that does not pass the declared validation, an exception of type javax.validation.ConstraintViolationException will be thrown and the entity will not be persisted.

As we can see, Bean Validation pretty much automates data validation, freeing us from having to manually write validation code.. [ 201 ]. Database Connectivity In addition to the two annota Software qr codes tions discussed in the previous example, the javax.validation.constraints package contains several additional annotations that we can use to automate validation on our JPA entities.

Refer to the Java EE 6 API documentation at http://java.sun.com/javaee/6/docs/api/ for the complete list.

. Summary. This chapter covered how to a Software Quick Response Code ccess data in a database via both the Java Database Connectivity (JDBC) and through the Java Persistence API (JPA). We covered how to obtain data from the database by using JDBC via the executeQuery() method defined in the java.sql.

PreparedStatement interface. We also covered how to insert, update, and delete data in the database via the executeUpdate() method defined in the same interface. Additionally, using dependency injection to inject a DataSource into an object was also covered.

Setting a Java class as an entity by decorating it with the @Entity annotation was also covered. Additionally, we covered how to map an entity to a database table via the @Table annotation. We also covered how to map entity fields to database columns via the @Column annotation, as well as declaring an entity"s primary key via the @Id annotation.

Using the javax.persistence.EntityManager interface to find, persist, and update JPA entities was also covered.

Defining both unidirectional and bidirectional one-to-one, one-to-many, and many-to-many relationships between JPA entities was covered as well. Additionally, we covered how to use JPA composite primary keys by developing custom primary key classes. We also covered how to retrieve entities from a database by using the Java Persistence Query Language (JPQL).

We then discussed some new JPA 2.0 features such as the Criteria API that allows us to build JPA queries programmatically, the Metamodel API that allows us to take advantage of Java"s type safety when working with JPA, and Bean Validation that allows us to easily validate input by simply annotating our JPA entity fields..

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