PropertyQuery.java

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2011, Red Hat, Inc. and/or its affiliates, and individual
 * contributors by the @authors tag. See the copyright.txt in the
 * distribution for a full listing of individual contributors.
 *
 * 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.jboss.solder.properties.query;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import org.jboss.solder.properties.MethodProperty;
import org.jboss.solder.properties.Properties;
import org.jboss.solder.properties.Property;

/**
 * <p>
 * Queries a target class for properties that match certain criteria. A property
 * may either be a private or public field, declared by the target class or
 * inherited from a superclass, or a public method declared by the target class
 * or inherited from any of its superclasses. For properties that are exposed
 * via a method, the property must be a JavaBean style property, i.e. it must
 * provide both an accessor and mutator method according to the JavaBean
 * specification.
 * </p>
 * <p/>
 * <p>
 * This class is not thread-safe, however the result returned by the
 * getResultList() method is.
 * </p>
 *
 * @author Shane Bryzak
 * @see PropertyQueries
 * @see PropertyCriteria
 */
public class PropertyQuery<V> {
    private final Class<?> targetClass;
    private final List<PropertyCriteria> criteria;

    PropertyQuery(Class<?> targetClass) {
        if (targetClass == null) {
            throw new IllegalArgumentException("targetClass parameter may not be null");
        }

        this.targetClass = targetClass;
        this.criteria = new ArrayList<PropertyCriteria>();
    }

    /**
     * Add a criteria to query
     *
     * @param criteria the criteria to add
     */
    public PropertyQuery<V> addCriteria(PropertyCriteria criteria) {
        this.criteria.add(criteria);
        return this;
    }

    /**
     * Get the first result from the query, causing the query to be run.
     *
     * @return the first result, or null if there are no results
     */
    public Property<V> getFirstResult() {
        List<Property<V>> results = getResultList();
        return results.isEmpty() ? null : results.get(0);
    }

    /**
     * Get the first result from the query that is not marked as read only,
     * causing the query to be run.
     *
     * @return the first writable result, or null if there are no results
     */
    public Property<V> getFirstWritableResult() {
        List<Property<V>> results = getWritableResultList();
        return results.isEmpty() ? null : results.get(0);
    }

    /**
     * Get a single result from the query, causing the query to be run. An
     * exception is thrown if the query does not return exactly one result.
     *
     * @return the single result
     * @throws RuntimeException if the query does not return exactly one result
     */
    public Property<V> getSingleResult() {
        List<Property<V>> results = getResultList();
        if (results.size() == 1) {
            return results.get(0);
        } else if (results.isEmpty()) {
            throw new RuntimeException("Expected one property match, but the criteria did not match any properties on " + targetClass.getName());
        } else {
            throw new RuntimeException("Expected one property match, but the criteria matched " + results.size() + " properties on " + targetClass.getName());
        }
    }

    /**
     * Get a single result from the query that is not marked as read only,
     * causing the query to be run. An exception is thrown if the query does not
     * return exactly one result.
     *
     * @return the single writable result
     * @throws RuntimeException if the query does not return exactly one result
     */
    public Property<V> getWritableSingleResult() {
        List<Property<V>> results = getWritableResultList();
        if (results.size() == 1) {
            return results.get(0);
        } else if (results.isEmpty()) {
            throw new RuntimeException("Expected one property match, but the criteria did not match any properties on " + targetClass.getName());
        } else {
            throw new RuntimeException("Expected one property match, but the criteria matched " + results.size() + " properties on " + targetClass.getName());
        }
    }

    /**
     * Get the result from the query, causing the query to be run.
     *
     * @return the results, or an empty list if there are no results
     */
    public List<Property<V>> getResultList() {
        return getResultList(false);
    }

    /**
     * Get the non read only results from the query, causing the query to be run.
     *
     * @return the results, or an empty list if there are no results
     */
    public List<Property<V>> getWritableResultList() {
        return getResultList(true);
    }

    /**
     * Get the result from the query, causing the query to be run.
     *
     * @param writable if this query should only return properties that are not
     *                 read only
     * @return the results, or an empty list if there are no results
     */
    private List<Property<V>> getResultList(boolean writable) {
        List<Property<V>> results = new ArrayList<Property<V>>();

        // First check public accessor methods (we ignore private methods)
        for (Method method : targetClass.getMethods()) {
            if (!(method.getName().startsWith("is") || method.getName().startsWith("get")))
                continue;

            boolean match = true;
            for (PropertyCriteria c : criteria) {
                if (!c.methodMatches(method)) {
                    match = false;
                    break;
                }
            }
            if (match) {
                MethodProperty<V> property = Properties.<V>createProperty(method);
                if (!writable || !property.isReadOnly()) {
                    results.add(property);
                }
            }
        }

        Class<?> cls = targetClass;
        while (cls != null && !cls.equals(Object.class)) {
            // Now check declared fields
            for (Field field : cls.getDeclaredFields()) {
                boolean match = true;
                for (PropertyCriteria c : criteria) {
                    if (!c.fieldMatches(field)) {
                        match = false;
                        break;
                    }
                }
                Property<V> prop = Properties.<V>createProperty(field);

                if (match && !resultsContainsProperty(results, prop.getName())) {
                    if (!writable || !prop.isReadOnly()) {
                        results.add(prop);
                    }
                }
            }

            cls = cls.getSuperclass();
        }

        return results;
    }

    private boolean resultsContainsProperty(List<Property<V>> results, String propertyName) {
        for (Property<V> p : results) {
            if (propertyName.equals(p.getName()))
                return true;
        }
        return false;
    }
}