org.hibernate.validator.internal.engine.ServiceLoaderBasedConstraintMappingContributor Maven / Gradle / Ivy
/*
* Hibernate Validator, declare and validate application constraints
*
* License: Apache License, Version 2.0
* See the license.txt file in the root directory or .
*/
package org.hibernate.validator.internal.engine;
import static org.hibernate.validator.internal.util.CollectionHelper.newHashMap;
import java.lang.annotation.Annotation;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import javax.validation.ConstraintValidator;
import org.hibernate.validator.cfg.ConstraintMapping;
import org.hibernate.validator.cfg.context.ConstraintDefinitionContext;
import org.hibernate.validator.internal.util.TypeResolutionHelper;
import org.hibernate.validator.internal.util.privilegedactions.GetInstancesFromServiceLoader;
import org.hibernate.validator.spi.cfg.ConstraintMappingContributor;
import com.fasterxml.classmate.ResolvedType;
/**
* Contributor of constraint definitions discovered by the Java service loader mechanism.
*
* @author Hardy Ferentschik
*/
public class ServiceLoaderBasedConstraintMappingContributor implements ConstraintMappingContributor {
/**
* Used for resolving type parameters. Thread-safe.
*/
private final TypeResolutionHelper typeResolutionHelper;
/**
* The primary class loader passed to the {@link ServiceLoader}.
*
* Tries this one then tries the class loader used to load Hibernate Validator classes.
*/
private final ClassLoader primaryClassLoader;
public ServiceLoaderBasedConstraintMappingContributor(TypeResolutionHelper typeResolutionHelper, ClassLoader primaryClassLoader) {
this.primaryClassLoader = primaryClassLoader;
this.typeResolutionHelper = typeResolutionHelper;
}
@SuppressWarnings("rawtypes")
@Override
public void createConstraintMappings(ConstraintMappingBuilder builder) {
Map, List>> customValidators = newHashMap();
// find additional constraint validators via the Java ServiceLoader mechanism
List discoveredConstraintValidators = run( GetInstancesFromServiceLoader.action( primaryClassLoader,
ConstraintValidator.class ) );
for ( ConstraintValidator constraintValidator : discoveredConstraintValidators ) {
Class constraintValidatorClass = constraintValidator.getClass();
Class annotationType = determineAnnotationType( constraintValidatorClass );
List> validators = customValidators.get( annotationType );
if ( annotationType != null && validators == null ) {
validators = new ArrayList>();
customValidators.put( annotationType, validators );
}
validators.add( constraintValidatorClass );
}
ConstraintMapping constraintMapping = builder.addConstraintMapping();
for ( Map.Entry, List>> entry : customValidators.entrySet() ) {
registerConstraintDefinition( constraintMapping, entry.getKey(), entry.getValue() );
}
}
@SuppressWarnings("unchecked")
private void registerConstraintDefinition(ConstraintMapping constraintMapping,
Class constraintType,
List> validatorTypes) {
ConstraintDefinitionContext context = constraintMapping
.constraintDefinition( (Class) constraintType )
.includeExistingValidators( true );
for ( Class validatorType : validatorTypes ) {
context.validatedBy( (Class>) validatorType );
}
}
@SuppressWarnings("rawtypes")
private Class determineAnnotationType(Class constraintValidatorClass) {
ResolvedType resolvedType = typeResolutionHelper.getTypeResolver()
.resolve( constraintValidatorClass );
return resolvedType.typeParametersFor( ConstraintValidator.class ).get( 0 ).getErasedType();
}
/**
* Runs the given privileged action, using a privileged block if required.
*
* NOTE: This must never be changed into a publicly available method to avoid execution of arbitrary
* privileged actions within HV's protection domain.
*/
private T run(PrivilegedAction action) {
return System.getSecurityManager() != null ? AccessController.doPrivileged( action ) : action.run();
}
}