org.force66.beantester.utils.InstantiationUtils.java Source code

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Here is the source code for org.force66.beantester.utils.InstantiationUtils.java

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/*
 * This software is licensed under the Apache License, Version 2.0
 * (the "License") agreement; 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 org.force66.beantester.utils;

import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.GregorianCalendar;
import java.util.List;

import javax.xml.datatype.DatatypeConfigurationException;
import javax.xml.datatype.DatatypeFactory;
import javax.xml.datatype.XMLGregorianCalendar;

import org.apache.commons.beanutils.ConstructorUtils;
import org.apache.commons.lang3.Validate;
import org.force66.beantester.valuegens.ValueGenerator;
import org.force66.beantester.valuegens.ValueGeneratorFactory;

/**
 * Helper for class instantiation
 * @author D. Ashmore
 *
 */
public class InstantiationUtils {

    public static Object safeNewInstance(Class<?> klass) {
        return safeNewInstance(klass, null);
    }

    public static Object safeNewInstance(ValueGeneratorFactory factory, Class<?> klass) {
        Validate.notNull(klass, "Null class not allowed.");
        Constructor<?> ctor = findPublicConstructor(klass);
        if (ctor == null) {
            throw new BeanTesterException("No public constructor found -- value generation isn't possible")
                    .addContextValue("class", klass.getName());
        }
        if (ctor.getParameterTypes().length == 0) {
            return safeNewInstance(klass, null);
        }

        ValueGenerator<?> generator = null;
        List<Object> constructorArgs = new ArrayList<Object>();
        for (Class<?> argType : ctor.getParameterTypes()) {
            generator = factory.forClass(argType);
            if (generator == null) {
                throw new BeanTesterException("Value can't be generated for constructor argument")
                        .addContextValue("class", klass.getName()).addContextValue("constructor", ctor)
                        .addContextValue("argument type", argType.getName());
            }
            constructorArgs.add(generator.makeValues()[0]);
        }

        return safeNewInstance(klass, constructorArgs.toArray());
    }

    public static Constructor<?> findPublicConstructor(Class<?> klass) {
        Validate.notNull(klass, "Null class not allowed.");
        Constructor<?> nullConstructor = ConstructorUtils.getAccessibleConstructor(klass, new Class<?>[0]);
        if (nullConstructor != null) {
            return nullConstructor;
        }

        Constructor<?>[] constructorArray = klass.getConstructors();
        for (Constructor<?> constructor : constructorArray) {
            if (Modifier.isPublic(constructor.getModifiers())) {
                return constructor;
            }
        }

        return null;
    }

    /**
     * newInstance() execution properly wrapped with exception handling.
     * @param klass
     * @return
     */
    public static Object safeNewInstance(Class<?> klass, Object[] constructorArgs) {
        Validate.notNull(klass, "Null class not allowed.");
        try {
            return ConstructorUtils.invokeConstructor(klass, constructorArgs);
        } catch (Exception e) {
            throw new BeanTesterException("Failed to instantiate bean using newInstance()", e)
                    .addContextValue("className", klass.getName());
        }
    }

    public static XMLGregorianCalendar newXMLGregorianCalendar() {
        try {
            return DatatypeFactory.newInstance().newXMLGregorianCalendar(new GregorianCalendar());
        } catch (DatatypeConfigurationException e) {
            throw new BeanTesterException("This shouldn't happen", e);
        }
    }

}