在Java SE中使用Hibernate Bean Validator

Bean Validation主页上指出：“ Bean Validation是Java规范，…在Java SE中运行，但集成在Java EE（6和7）中。” 这篇文章演示了如何在Java EE容器之外使用Java Bean验证参考实现（ Hibernate Validator ）。这篇文章中的示例基于Hibernate Validator 5.1.3 Final ，可从http://hibernate.org/validator/downloads下载。

“ Hibernate Validator入门 ”指出，Hibernate Validator需要统一表达语言（ JSR 341 ）和上下文和依赖项注入（ CDI / JSR 346 ）的实现。这些规范的实现可在符合Java EE的现代容器（应用程序服务器）中使用，但是在Java SE环境中使用Hibernate Validator需要采购和使用单独的实现。

“ Hibernate Validator入门”页面提供了一种Maven XML，可以用来识别对Expression Language API （我正在使用Expression Language 3.0 API ）， Expression Language实施（我正在使用Expression Language Implementation 2.2.6 ）的依赖性。，以及Hibernate Validator CDI便携式扩展（我正在使用Hibernate Validator便携式扩展5.1.3 Final ）。我还使用Bean Validation API 1.1.0 Final ， JBoss Logging 3.3.0 Final和ClassMate 1.2.0来构建和运行示例。

本文中演示的bean验证示例定义了三个Java类。 Car.java是从“ Hibernate Validator入门 ”页面上提供的示例改编而成的一类，接下来显示其代码清单。

汽车.java

package dustin.examples;import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;/*** Example adapted from "Getting Started with Hibernate Validator"* (http://hibernate.org/validator/documentation/getting-started/).*/
public class Car
{@NotNullprivate String manufacturer;@NotNull@Size(min = 2, max = 14)private String licensePlate;@Min(2)private int seatCount;public Car(final String manufacturer, final String licencePlate, final int seatCount){this.manufacturer = manufacturer;this.licensePlate = licencePlate;this.seatCount = seatCount;}public String getManufacturer(){return manufacturer;}public String getLicensePlate(){return licensePlate;}public int getSeatCount(){return seatCount;}@Overridepublic String toString(){return "Car{" +"manufacturer='" + manufacturer + '\'' +", licensePlate='" + licensePlate + '\'' +", seatCount=" + seatCount +'}';}
}

Garage.java定义了Garage.java示例中使用的另一个类， Garage.java主要是Car的多个实例的包装。它的主要目的是帮助说明Hibernate Bean Validator支持的递归验证。

车库.java

package dustin.examples;import javax.validation.Valid;
import javax.validation.constraints.Size;import java.util.Collections;
import java.util.HashSet;
import java.util.Set;/*** Holds cars.*/
public class Garage
{@Size(min = 1)@Validprivate final Set<Car> cars = new HashSet<>();public Garage() {}public void addCar(final Car newCar){cars.add(newCar);}public Set<Car> getCars(){return Collections.unmodifiableSet(this.cars);}
}

上面列出的Garage代码使用@Valid批注指示也应验证该类持有的Car实例（“验证级联”）。

本文的示例中使用的最后一个Java类是将实际执行两个带bean验证注释的类Car和Garage验证的类。该类的清单如下所示。

HibernateValidatorDemonstration.java

package dustin.examples;import static java.lang.System.out;import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.ValidatorFactory;
import javax.validation.Validator;
import java.util.Set;/*** Demonstrate use of Hibernate Validator.*/
public class HibernateValidatorDemonstration
{private final Validator validator;public HibernateValidatorDemonstration(){final ValidatorFactory factory = Validation.buildDefaultValidatorFactory();validator = factory.getValidator();}public void demonstrateValidator(){final Car nullManufacturerCar = new Car(null, "ABC123", 4);final Set<ConstraintViolation<Car>> nullMfgViolations = validator.validate(nullManufacturerCar);printConstraintViolationsToStandardOutput("Null Manufacturer Example", nullMfgViolations);final Car nullLicenseCar = new Car("Honda", null, 3);final Set<ConstraintViolation<Car>> nullLicenseViolations = validator.validate(nullLicenseCar);printConstraintViolationsToStandardOutput("Null License Example", nullLicenseViolations);final Car oneSeatCar = new Car("Toyota", "123ABC", 1);final Set<ConstraintViolation<Car>> tooFewSeatsViolations = validator.validate(oneSeatCar);printConstraintViolationsToStandardOutput("Too Few Seats Example", tooFewSeatsViolations);final Car oneDigitLicenseCar = new Car("General Motors", "I", 2);final Set<ConstraintViolation<Car>> tooFewLicenseDigitsViolation = validator.validate(oneDigitLicenseCar);printConstraintViolationsToStandardOutput("Too Few License Digits Example", tooFewLicenseDigitsViolation);final Car nullManufacturerNullLicenseCar = new Car(null, null, 4);final Set<ConstraintViolation<Car>> nullMfgLicenseViolation = validator.validate(nullManufacturerNullLicenseCar);printConstraintViolationsToStandardOutput("Null Manufacturer and Null License Example", nullMfgLicenseViolation);final Garage garage = new Garage();final Set<ConstraintViolation<Garage>> noCarsInGarage = validator.validate(garage);printConstraintViolationsToStandardOutput("No Cars in Garage", noCarsInGarage);garage.addCar(oneDigitLicenseCar);garage.addCar(oneSeatCar);garage.addCar(nullManufacturerNullLicenseCar);final Set<ConstraintViolation<Garage>> messedUpCarsInGarage = validator.validate(garage);printConstraintViolationsToStandardOutput("Messed Up Cars in Garage", messedUpCarsInGarage);}private <T> void printConstraintViolationsToStandardOutput(final String title,final Set<ConstraintViolation<T>> violations){out.println(title);for (final ConstraintViolation<T> violation : violations){out.println("\t" + violation.getPropertyPath() + " " + violation.getMessage());}}public static void main(final String[] arguments){final HibernateValidatorDemonstration instance = new HibernateValidatorDemonstration();instance.demonstrateValidator();}
}

上面的代码具有对javax.validation.Validator.validate（T，Class <？>）的多次调用，这些调用演示了对正在验证其实例的类的注释的有效性。几个示例验证对象的单个验证冲突，一个示例验证对象的多个验证冲突，最后一个示例演示成功的级联冲突检测。

HibernateValidatorDemonstration类具有main(String[])函数，可以在Java SE环境中执行该函数（假定必需的JAR位于运行时类路径上）。接下来显示运行上述演示类的输出：

Jul 19, 2015 9:30:05 PM org.hibernate.validator.internal.util.Version 
INFO: HV000001: Hibernate Validator 5.1.3.Final
Null Manufacturer Examplemanufacturer may not be null
Null License ExamplelicensePlate may not be null
Too Few Seats ExampleseatCount must be greater than or equal to 2
Too Few License Digits ExamplelicensePlate size must be between 2 and 14
Null Manufacturer and Null License Examplemanufacturer may not be nulllicensePlate may not be null
No Cars in Garagecars size must be between 1 and 2147483647
Messed Up Cars in Garagecars[].licensePlate size must be between 2 and 14cars[].manufacturer may not be nullcars[].licensePlate may not be nullcars[].seatCount must be greater than or equal to 2