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一、创建一个简单的约束
1. 约束注释
- 枚举表示大小写
public enum CaseMode {
UPPER,
LOWER;
}- 定义@CheckCase约束
import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.ElementType.TYPE_USE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
@Target({ FIELD, METHOD, PARAMETER, ANNOTATION_TYPE, TYPE_USE })
@Retention(RUNTIME)
@Constraint(validatedBy = CheckCaseValidator.class)
@Documented
@Repeatable(List.class)
public @interface CheckCase {
String message() default "{org.hibernate.validator.referenceguide.chapter06.CheckCase."
"message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
CaseMode value();
@Target({ FIELD, METHOD, PARAMETER, ANNOTATION_TYPE })
@Retention(RUNTIME)
@Documented
@interface List {
CheckCase[] value();
}
}- 测试一下吧
public class Severity {
public interface Info extends Payload {
}
public interface Error extends Payload {
}
}public class ContactDetails {
@NotNull(message = "Name is mandatory", payload = Severity.Error.class)
private String name;
@NotNull(message = "Phone number not specified, but not mandatory",
payload = Severity.Info.class)
private String phoneNumber;
// ...
}用法
@Target 定义约束所支持的目标元素类型
@Retention(RUNTIME)：指定此类型的注释将在运行时通过反射方式提供
@Constraint(validatedBy = CheckCaseValidator.class)：将注释类型标记为约束注释，并指定用于验证元素的验证器
@CheckCase。如果可以在几种数据类型上使用约束，则可以指定几个验证器，每种数据类型一个。
@Repeatable(List.class)：表示注释可以在同一位置重复多次，通常使用不同的配置
2. 约束验证器
代码语言：javascript复制public class CheckCaseValidator implements ConstraintValidator<CheckCase, String> {
private CaseMode caseMode;
@Override
public void initialize(CheckCase constraintAnnotation) {
this.caseMode = constraintAnnotation.value();
}
@Override
public boolean isValid(String object, ConstraintValidatorContext constraintContext) {
if ( object == null ) {
return true;
}
if ( caseMode == CaseMode.UPPER ) {
return object.equals( object.toUpperCase() );
}
else {
return object.equals( object.toLowerCase() );
}
}
}- 自定义错误消息
public class CheckCaseValidator implements ConstraintValidator<CheckCase, String> {
private CaseMode caseMode;
@Override
public void initialize(CheckCase constraintAnnotation) {
this.caseMode = constraintAnnotation.value();
}
@Override
public boolean isValid(String object, ConstraintValidatorContext constraintContext) {
if ( object == null ) {
return true;
}
boolean isValid;
if ( caseMode == CaseMode.UPPER ) {
isValid = object.equals( object.toUpperCase() );
}
else {
isValid = object.equals( object.toLowerCase() );
}
if ( !isValid ) {
constraintContext.disableDefaultConstraintViolation();
constraintContext.buildConstraintViolationWithTemplate(
"{org.hibernate.validator.referenceguide.chapter06."
"constraintvalidatorcontext.CheckCase.message}"
)
.addConstraintViolation();
}
return isValid;
}
}- HibernateConstraintValidator（对原版进行扩展）
public class MyFutureValidator implements HibernateConstraintValidator<MyFuture, Instant> {
private Clock clock;
private boolean orPresent;
@Override
public void initialize(ConstraintDescriptor<MyFuture> constraintDescriptor,
HibernateConstraintValidatorInitializationContext initializationContext) {
this.orPresent = constraintDescriptor.getAnnotation().orPresent();
this.clock = initializationContext.getClockProvider().getClock();
}
@Override
public boolean isValid(Instant instant, ConstraintValidatorContext constraintContext) {
//...
return false;
}
}将有效负载传递给约束验证器
- 在ValidatorFactory初始化期间定义约束验证器有效载荷
代码语言：javascript复制ValidatorFactory validatorFactory = Validation.byProvider( HibernateValidator.class )
.configure()
.constraintValidatorPayload( "US" )
.buildValidatorFactory();
Validator validator = validatorFactory.getValidator();- 使用Validator上下文定义约束验证器有效载荷
HibernateValidatorFactory hibernateValidatorFactory = Validation.byDefaultProvider()
.configure()
.buildValidatorFactory()
.unwrap( HibernateValidatorFactory.class );
Validator validator = hibernateValidatorFactory.usingContext()
.constraintValidatorPayload( "US" )
.getValidator();
// [...] US specific validation checks
validator = hibernateValidatorFactory.usingContext()
.constraintValidatorPayload( "FR" )
.getValidator();
// [...] France specific validation checks- 在约束验证器中使用约束验证器有效载荷
public class ZipCodeValidator implements ConstraintValidator<ZipCode, String> {
public String countryCode;
@Override
public boolean isValid(String object, ConstraintValidatorContext constraintContext) {
if ( object == null ) {
return true;
}
boolean isValid = false;
String countryCode = constraintContext
.unwrap( HibernateConstraintValidatorContext.class )
.getConstraintValidatorPayload( String.class );
if ( "US".equals( countryCode ) ) {
// checks specific to the United States
}
else if ( "FR".equals( countryCode ) ) {
// checks specific to France
}
else {
// ...
}
return isValid;
}
}3. 错误讯息
代码语言：javascript复制org.hibernate.validator.referenceguide.chapter06.CheckCase.message = 案例模式必须为{value}。4. 使用约束
代码语言：javascript复制public class Car {
@NotNull
private String manufacturer;
@NotNull
@Size(min = 2, max = 14)
@CheckCase(CaseMode.UPPER)
private String licensePlate;
@Min(2)
private int seatCount;
public Car(String manufacturer, String licencePlate, int seatCount) {
this.manufacturer = manufacturer;
this.licensePlate = licencePlate;
this.seatCount = seatCount;
}
//getters and setters ...
}- 使用约束验证对象
//invalid license plate
Car car = new Car( "Morris", "dd-ab-123", 4 );
Set<ConstraintViolation<Car>> constraintViolations =
validator.validate( car );
assertEquals( 1, constraintViolations.size() );
assertEquals(
"Case mode must be UPPER.",
constraintViolations.iterator().next().getMessage()
);
//valid license plate
car = new Car( "Morris", "DD-AB-123", 4 );
constraintViolations = validator.validate( car );
assertEquals( 0, constraintViolations.size() );二、类级别约束
- 实现一个类级别约束
@Target({ TYPE, ANNOTATION_TYPE })
@Retention(RUNTIME)
@Constraint(validatedBy = { ValidPassengerCountValidator.class })
@Documented
public @interface ValidPassengerCount {
String message() default "{org.hibernate.validator.referenceguide.chapter06.classlevel."
"ValidPassengerCount.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
}public class ValidPassengerCountValidator
implements ConstraintValidator<ValidPassengerCount, Car> {
@Override
public void initialize(ValidPassengerCount constraintAnnotation) {
}
@Override
public boolean isValid(Car car, ConstraintValidatorContext context) {
if ( car == null ) {
return true;
}
return car.getPassengers().size() <= car.getSeatCount();
}
}自定义属性路径
代码语言：javascript复制public class ValidPassengerCountValidator
implements ConstraintValidator<ValidPassengerCount, Car> {
@Override
public void initialize(ValidPassengerCount constraintAnnotation) {
}
@Override
public boolean isValid(Car car, ConstraintValidatorContext constraintValidatorContext) {
if ( car == null ) {
return true;
}
boolean isValid = car.getPassengers().size() <= car.getSeatCount();
if ( !isValid ) {
constraintValidatorContext.disableDefaultConstraintViolation();
constraintValidatorContext
.buildConstraintViolationWithTemplate( "{my.custom.template}" )
.addPropertyNode( "passengers" ).addConstraintViolation();
}
return isValid;
}
}三、交叉级别约束
- 交叉级别约束
@Constraint(validatedBy = ConsistentDateParametersValidator.class)
@Target({ METHOD, CONSTRUCTOR, ANNOTATION_TYPE })
@Retention(RUNTIME)
@Documented
public @interface ConsistentDateParameters {
String message() default "{org.hibernate.validator.referenceguide.chapter04."
"crossparameter.ConsistentDateParameters.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
}- 通用和交叉级别约束
@SupportedValidationTarget(ValidationTarget.PARAMETERS)
public class ConsistentDateParametersValidator implements
ConstraintValidator<ConsistentDateParameters, Object[]> {
@Override
public void initialize(ConsistentDateParameters constraintAnnotation) {
}
@Override
public boolean isValid(Object[] value, ConstraintValidatorContext context) {
if ( value.length != 2 ) {
throw new IllegalArgumentException( "Illegal method signature" );
}
//leave null-checking to @NotNull on individual parameters
if ( value[0] == null || value[1] == null ) {
return true;
}
if ( !( value[0] instanceof Date ) || !( value[1] instanceof Date ) ) {
throw new IllegalArgumentException(
"Illegal method signature, expected two "
"parameters of type Date."
);
}
return ( (Date) value[0] ).before( (Date) value[1] );
}
}@Constraint(validatedBy = {
ScriptAssertObjectValidator.class,
ScriptAssertParametersValidator.class
})
@Target({ TYPE, FIELD, PARAMETER, METHOD, CONSTRUCTOR, ANNOTATION_TYPE })
@Retention(RUNTIME)
@Documented
public @interface ScriptAssert {
String message() default "{org.hibernate.validator.referenceguide.chapter04."
"crossparameter.ScriptAssert.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
String script();
ConstraintTarget validationAppliesTo() default ConstraintTarget.IMPLICIT;
}- 指定通用和交叉参数约束的目标
@ScriptAssert(script = "arg1.size() <= arg0", validationAppliesTo = ConstraintTarget.PARAMETERS)
public Car buildCar(int seatCount, List<Passenger> passengers) {
//...
return null;
}四、约束构成
- 创建一个合成约束 @ValidLicensePlate
@NotNull
@Size(min = 2, max = 14)
@CheckCase(CaseMode.UPPER)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, TYPE_USE })
@Retention(RUNTIME)
@Constraint(validatedBy = { })
@Documented
public @interface ValidLicensePlate {
String message() default "{org.hibernate.validator.referenceguide.chapter06."
"constraintcomposition.ValidLicensePlate.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
}- 组合约束的应用 ValidLicensePlate
public class Car {
@ValidLicensePlate
private String licensePlate;
//...
}- 使用@ReportAsSingleViolation
@ReportAsSingleViolation
public @interface ValidLicensePlate {
String message() default "{org.hibernate.validator.referenceguide.chapter06."
"constraintcomposition.reportassingle.ValidLicensePlate.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
}
```ayload() default { };
}本文由 mdnice 多平台发布
