org.onebusaway.gtfs_transformer.deferred.DeferredValueConverter.java Source code

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Here is the source code for org.onebusaway.gtfs_transformer.deferred.DeferredValueConverter.java

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/**
 * Copyright (C) 2012 Google, Inc.
 *
 * 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.onebusaway.gtfs_transformer.deferred;

import java.io.Serializable;
import java.lang.reflect.Method;

import org.apache.commons.beanutils.Converter;
import org.onebusaway.csv_entities.schema.BeanWrapper;
import org.onebusaway.gtfs.model.AgencyAndId;
import org.onebusaway.gtfs.model.IdentityBean;
import org.onebusaway.gtfs.serialization.GtfsReader;
import org.onebusaway.gtfs.serialization.GtfsReaderContext;
import org.onebusaway.gtfs.services.GtfsRelationalDao;

/**
 * In {@lint ValueSetter} implementations, the source value is often a primitive
 * string but the target value type is often something more complex: a numeric
 * type, a {@link AgencyAndId}, a field with GTFS-specific formatting, or even a
 * GTFS entity. Often, the value cannot be properly converted until the moment
 * of assignment, as it must be resolved against existing and previously
 * assigned values.
 * 
 *  This class provides methods for converting the input value into a resolved
 * value appropriate for assignment.
 */
public class DeferredValueConverter {

    private final DeferredValueSupport _support;

    private final GtfsRelationalDao _dao;

    public DeferredValueConverter(GtfsReader reader, EntitySchemaCache schemaCache, GtfsRelationalDao dao) {
        _support = new DeferredValueSupport(reader, schemaCache);
        _dao = dao;
    }

    /**
     * Converts the specified value as appropriate such that the resulting value
     * can be assigned to the specified property of the specified bean.
     */
    public Object convertValue(BeanWrapper targetBean, String targetPropertyName, Object value) {
        if (value == null) {
            return null;
        }
        Class<?> expectedValueType = targetBean.getPropertyType(targetPropertyName);
        Class<?> actualValueType = value.getClass();

        /**
         * When we introspect the "id" property of an IdentityBean instance, the
         * return type is always Serializable, when the actual type is String or
         * AgencyAndId. This causes trouble with the "isAssignableFrom" check below,
         * so we do a first check here.
         */
        Object parentObject = targetBean.getWrappedInstance(Object.class);
        if (parentObject instanceof IdentityBean && targetPropertyName.equals("id")) {
            Class<?> idType = getIdentityBeanIdType(parentObject);
            if (idType == AgencyAndId.class && actualValueType == String.class) {
                return _support.resolveAgencyAndId(targetBean, targetPropertyName, (String) value);
            }
        }

        if (expectedValueType.isAssignableFrom(actualValueType)) {
            return value;
        }

        if (isPrimitiveAssignable(expectedValueType, actualValueType)) {
            return value;
        }

        if (actualValueType == String.class) {
            String stringValue = (String) value;
            if (AgencyAndId.class.isAssignableFrom(expectedValueType)) {
                return _support.resolveAgencyAndId(targetBean, targetPropertyName, stringValue);
            }

            if (IdentityBean.class.isAssignableFrom(expectedValueType)) {
                Serializable id = stringValue;
                if (getIdType(expectedValueType) == AgencyAndId.class) {
                    GtfsReaderContext context = _support.getReader().getGtfsReaderContext();
                    String agencyId = context.getAgencyForEntity(expectedValueType, stringValue);
                    id = new AgencyAndId(agencyId, stringValue);
                }
                Object entity = _dao.getEntityForId(expectedValueType, id);
                if (entity == null) {
                    throw new IllegalStateException(
                            "entity not found: type=" + expectedValueType.getName() + " id=" + id);
                }
                return entity;
            }
            Class<?> parentEntityType = parentObject.getClass();
            Converter converter = _support.resolveConverter(parentEntityType, targetPropertyName,
                    expectedValueType);
            if (converter != null) {
                return converter.convert(expectedValueType, value);
            }
        }

        throw new IllegalStateException("no conversion possible from type \"" + actualValueType.getName()
                + "\" to type \"" + expectedValueType.getName() + "\"");
    }

    private Class<?> getIdentityBeanIdType(Object bean) {
        try {
            return bean.getClass().getMethod("getId").getReturnType();
        } catch (NoSuchMethodException e) {
            throw new IllegalStateException(e);
        }
    }

    private boolean isPrimitiveAssignable(Class<?> expectedValueType, Class<?> actualValueType) {
        if (!expectedValueType.isPrimitive()) {
            return false;
        }
        return expectedValueType == Double.TYPE
                && (actualValueType == Double.class || actualValueType == Float.class)
                || expectedValueType == Long.TYPE && (actualValueType == Long.class
                        || actualValueType == Integer.class || actualValueType == Short.class)
                || expectedValueType == Integer.TYPE
                        && (actualValueType == Integer.class || actualValueType == Short.class)
                || expectedValueType == Short.TYPE && (actualValueType == Short.class)
                || expectedValueType == Boolean.TYPE && (actualValueType == Boolean.class);
    }

    private static Class<?> getIdType(Class<?> valueType) {
        try {
            Method m = valueType.getMethod("getId");
            return m.getReturnType();
        } catch (Throwable ex) {
            throw new IllegalStateException("could not find method \"getId\" for IdentityBean classs", ex);
        }
    }
}