Learn about the technical principles of the Bean Validation Scala framework in the Java class library

Bean Validation is a framework for verifying data in the Java class library. It provides a simple and flexible way to verify the attributes of the Java physical object.SCALA is a JVM -based programming language, which combines the characteristics of object -oriented and functional programming.The Bean Validation Scala framework is to enable SCALA developers to use the Bean Validation framework to verify the data in the SCALA application. The technical principles of the Bean Validation Scala framework can be explained by the following steps: 1. Definition verification constraint Note: The Bean Validation framework allows developers to define verification constraints by writing annotations.For example, you can define a `@noteMpty` annotation to verify that the string attribute cannot be empty. scala import javax.validation.constraints.NotEmpty class User { @Notempty (Message = "Username cannot be empty") var name: String = _ } 2. Contains Bean Validation dependencies: In the construction file of the Scala project (such as Build.SBT), the dependencies of Bean Validation need to be added.For example, Hibernate Validator can be used as a bean value provider. scala libraryDependencies += "org.hibernate.validator" % "hibernate-validator" % "6.0.18.Final" 3. Create a verification device: Create an authenticator instance where you need to verify the data. scala import javax.validation.Validation import scala.reflect.runtime.universe._ class UserValidator { private val validator = Validation.buildDefaultValidatorFactory.getValidator def validate[T: TypeTag](obj: T): Set[String] = { val violations = validator.validate(obj) violations.map(_.getMessage).toSet } } This `UserValidator` class uses the` value of java to build the default verification factory and obtain an instance of the verification device through the `GetValidator" method.Then, the `validate` method receives a generic object,` obj` as an input, and use the verification device to verify it.Finally, a collection of messages that verify failed. 4. Execution verification: Use the created authentication instance to perform verification operations on Java or SCALA entity objects. scala val user = new User() val validator = new UserValidator() val violations = validator.validate(user) if (violations.nonEmpty) { violations.foreach(println) } else { Println ("Verification Pass") } In the above examples, first create an `User` object, and then create an instance of a` UserValidator.Use the `Validate` method to perform verification operations on the` user` object, and store the message collection of verification failure in the `violatings` variable.Finally, the corresponding message is output according to the verification results. In summary, the Bean Validation Scala framework uses Bean Validation's verification device and annotation mechanism to implement the data verification function in the SCALA application.Developers can use the existing Bean Validation constraint annotation, or customize new annotations to define data verification rules, and verify the data through the verification device.This method simplifies the process of data verification, which improves the maintenance and reused of code. It is hoped that this article will help the technical principles of understanding the Bean Validation Scala framework and the corresponding Java code example.