org.eclipse.osbp.jpa.services/src/org/eclipse/osbp/jpa/services/metadata/PropertyMetadata.java

/**
 * Copyright 2009-2013 Oy Vaadin Ltd
 *
 * 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 org.eclipse.osbp.jpa.services.metadata;

import java.io.InvalidObjectException;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;

/**
 * This class represents the metadata of a property. If the property is
 * transient, this is an ordinary JavaBean property consisting of a getter
 * method and optionally a setter method. If the property is persistent,
 * additional information is provided by the {@link PersistentPropertyMetadata}
 * interface.
 * 
 * @see ClassMetadata
 * @author Petter Holmström (Vaadin Ltd)
 * @since 1.0
 */
public class PropertyMetadata implements Serializable {

    private static final long serialVersionUID = -6500231861860229121L;
    private final String name;
    private final Class<?> type;
    transient final Method getter;
    transient final Method setter;
    // Required for serialization:
    protected final String getterName;
    protected final String setterName;
    protected final Class<?> getterDeclaringClass;
    protected final Class<?> setterDeclaringClass;

    /**
     * Creates a new instance of <code>PropertyMetadata</code>.
     * 
     * @param name
     *            the name of the property (must not be null).
     * @param type
     *            the type of the property (must not be null).
     * @param getter
     *            the getter method that can be used to read the value of the
     *            property (must not be null).
     * @param setter
     *            the setter method that can be used to set the value of the
     *            property (may be null).
     */
    PropertyMetadata(String name, Class<?> type, Method getter, Method setter) {
        assert name != null : "name must not be null";
        assert type != null : "type must not be null";
        /*
         * If we assert that getter != null, PersistentPropertyMetadata will not
         * work.
         */
        this.name = name;
        this.type = type;
        this.getter = getter;
        this.setter = setter;
        /*
         * The getter may also be null, e.g. if PersistentPropertyMetadata uses
         * a field instead of a getter to access the property.
         */
        if (getter != null) {
            getterName = getter.getName();
            getterDeclaringClass = getter.getDeclaringClass();
        } else {
            getterName = null;
            getterDeclaringClass = null;
        }
        if (setter != null) {
            setterName = setter.getName();
            setterDeclaringClass = setter.getDeclaringClass();
        } else {
            setterName = null;
            setterDeclaringClass = null;
        }
    }

    public Object readResolve() throws ObjectStreamException {
        try {
            Method getterM = null;
            if (getterName != null) {
                getterM = getterDeclaringClass.getDeclaredMethod(getterName);
            }
            Method setterM = null;
            if (setterName != null) {
                setterM = setterDeclaringClass.getDeclaredMethod(setterName,
                        type);
            }
            return new PropertyMetadata(name, type, getterM, setterM);
        } catch (Exception e) {
            throw new InvalidObjectException(e.getMessage());
        }
    }

    /**
     * The name of the property.
     */
    public String getName() {
        return name;
    }

    /**
     * The type of the property.
     */
    public Class<?> getType() {
        return type;
    }

    /**
     * The annotations of the property, if any.
     * 
     * @see #getAnnotation(java.lang.Class)
     */
    public Annotation[] getAnnotations() {
        return getter.getAnnotations();
    }

    /**
     * Gets the annotation of the specified annotation class, if available.
     * 
     * @see #getAnnotations()
     * @see Class#getAnnotation(java.lang.Class)
     * @param annotationClass
     *            the annotation class.
     * @return the annotation, or null if not found.
     */
    public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
        return getter.getAnnotation(annotationClass);
    }

    /**
     * Returns whether the property is writable or not. Transient properties
     * (i.e. JavaBean properties) are only writable if they have a setter
     * method.
     * 
     * @return true if the property is writable, false if it is not.
     */
    public boolean isWritable() {
        return setter != null;
    }
    
    public PropertyKind getPropertyKind() {
        return PropertyKind.NONPERSISTENT;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj != null && obj.getClass() == getClass()) {
            PropertyMetadata other = (PropertyMetadata) obj;
            return name.equals(other.name)
                    && type.equals(other.type)
                    && (getter == null ? other.getter == null : getter
                            .equals(other.getter))
                    && (setter == null ? other.setter == null : setter
                            .equals(other.setter));
        }
        return false;
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = hash * 31 + name.hashCode();
        hash = hash * 31 + type.hashCode();
        if (getter != null) {
            hash = hash * 31 + getter.hashCode();
        }
        if (setter != null) {
            hash = hash * 31 + setter.hashCode();
        }
        return hash;
    }
}