AbstractValidator.java

/*
 * Copyright 2011 Martin Grotzke
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package de.hashcode.validation;

import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Locale;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import javax.validation.ConstraintValidator;

/**
 * Abstract base class for annotation based validators.
 *
 * @author <a href="mailto:martin.grotzke@googlemail.com">Martin Grotzke</a>
 */
public abstract class AbstractValidator<T extends Annotation> implements ConstraintValidator<T, Object> {

    @CheckForNull
    protected Object getPropertyValue(@Nonnull final Object object, @Nonnull final String propertyName)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        final Method method = getGetter(object.getClass(), propertyName);
        return method.invoke(object, (Object[]) null);
    }

    @Nonnull
    private String toMethodName(@Nonnull final String methodPrefix, @Nonnull final String propertyName) {
        return methodPrefix + propertyName.substring(0, 1).toUpperCase(Locale.ENGLISH) + propertyName.substring(1);
    }

    @Nonnull
    private Method getGetter(@Nonnull final Class<?> clazz, @Nonnull final String property) {
        final String get = toMethodName("get", property);
        final String is = toMethodName("is", property);
        Method getter;
        try {
            getter = clazz.getMethod(get);
        } catch (final NoSuchMethodException noSuchMethodException) {
            try {
                getter = clazz.getMethod(is);
            } catch (final NoSuchMethodException noSuchMethodException2) {
                throw new RuntimeException("Getter for '" + clazz.getSimpleName() + '#' + property + "' not found.",
                        noSuchMethodException2);
            } catch (final SecurityException securityException) {
                throw new RuntimeException("Method '" + clazz.getSimpleName() + '#' + is
                        + "()' is protected by the security manager.");
            }
        } catch (final SecurityException securityException) {
            try {
                getter = clazz.getMethod(is);
            } catch (final NoSuchMethodException noSuchMethodException) {
                throw new RuntimeException("Method '" + clazz.getSimpleName() + '#' + get
                        + "()' is protected by the security manager.");
            } catch (final SecurityException securityException2) {
                throw new RuntimeException("Methods '" + clazz.getSimpleName() + '#' + get + "()' and "
                        + clazz.getSimpleName() + '#' + is + "()' are protected by the security manager.");
            }
        }
        return getter;
    }

}