FieldsCache.java

/*
 * Copyright (c) www.bugull.com
 * 
 * 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 net.tooan.ynpay.third.mongodb.cache;

import net.tooan.ynpay.third.jfinal.log.Logger;
import net.tooan.ynpay.third.mongodb.annotations.*;
import net.tooan.ynpay.third.mongodb.exception.FieldException;
import net.tooan.ynpay.third.mongodb.exception.IdException;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * Cache(Map) contains entity classes' fields, for performance purporse.
 *
 * @author Frank Wen(xbwen@hotmail.com)
 */
public class FieldsCache {

    private final static Logger logger = Logger.getLogger(FieldsCache.class);

    private static FieldsCache instance = new FieldsCache();

    private final ConcurrentMap<String, Field[]> cache = new ConcurrentHashMap<String, Field[]>();

    private FieldsCache() {

    }

    public static FieldsCache getInstance() {
        return instance;
    }

    /**
     * Get all declared and inherited field
     *
     * @param clazz
     * @return
     */
    private Field[] getAllFields(Class<?> clazz) {
        List<Field> allFields = new ArrayList<Field>();
        allFields.addAll(filterFields(clazz.getDeclaredFields()));
        Class parent = clazz.getSuperclass();
        while ((parent != null) && (parent != Object.class)) {
            allFields.addAll(filterFields(parent.getDeclaredFields()));
            parent = parent.getSuperclass();
        }
        return allFields.toArray(new Field[allFields.size()]);
    }

    /**
     * Filter the static filed, and set all the filed to alccessibe=true
     *
     * @param fields
     * @return
     */
    private List<Field> filterFields(Field[] fields) {
        List<Field> result = new ArrayList<Field>();
        for (Field field : fields) {
            if (!Modifier.isStatic(field.getModifiers())) {
                field.setAccessible(true);
                result.add(field);
            }
        }
        return result;
    }

    public Field[] get(Class<?> clazz) {
        String name = clazz.getName();
        Field[] fields = cache.get(name);
        if (fields != null) {
            return fields;
        }

        fields = getAllFields(clazz);
        Field[] temp = cache.putIfAbsent(name, fields);
        if (temp != null) {
            return temp;
        } else {
            return fields;
        }
    }

    /**
     * Get the field with @Id on it.
     *
     * @param clazz
     * @return
     */
    public Field getIdField(Class<?> clazz) throws IdException {
        Field result = null;
        Field[] fields = get(clazz);
        for (Field f : fields) {
            if (f.getAnnotation(Id.class) != null) {
                result = f;
                break;
            }
        }
        if (result == null) {
            throw new IdException(clazz.getName() + " does not contain @Id field.");
        }
        return result;
    }

    /**
     * Get the field's name with @Id on it. In natural case, it returns "id".
     *
     * @param clazz
     * @return
     */
    public String getIdFieldName(Class<?> clazz) {
        String name = null;
        Field f = null;
        try {
            f = this.getIdField(clazz);
        } catch (IdException ex) {
            logger.error(ex.getMessage(), ex);
        }
        if (f != null) {
            name = f.getName();
        }
        return name;
    }

    /**
     * Get the field by field name.
     *
     * @param clazz
     * @param fieldName
     * @return
     * @throws FieldException
     */
    public Field getField(Class<?> clazz, String fieldName) throws FieldException {
        Field field = null;
        Field[] fields = get(clazz);
        for (Field f : fields) {
            if (f.getName().equals(fieldName)) {
                field = f;
                break;
            }
        }
        if (field == null) {
            for (Field f : fields) {
                Property property = f.getAnnotation(Property.class);
                if (property != null && property.name().equals(fieldName)) {
                    field = f;
                    break;
                }
                Embed embed = f.getAnnotation(Embed.class);
                if (embed != null && embed.name().equals(fieldName)) {
                    field = f;
                    break;
                }
                EmbedList el = f.getAnnotation(EmbedList.class);
                if (el != null && el.name().equals(fieldName)) {
                    field = f;
                    break;
                }
                Ref ref = f.getAnnotation(Ref.class);
                if (ref != null && ref.name().equals(fieldName)) {
                    field = f;
                    break;
                }
                RefList rl = f.getAnnotation((RefList.class));
                if (rl != null && rl.name().equals(fieldName)) {
                    field = f;
                    break;
                }
            }
        }
        if (field == null) {
            throw new FieldException("Field '" + fieldName + "' does not exists!");
        }
        return field;
    }

    /**
     * check if the field is annotated by @EmbedList
     *
     * @param clazz
     * @param fieldName
     * @return
     */
    public boolean isEmbedListField(Class<?> clazz, String fieldName) {
        boolean result = false;
        Field[] fields = get(clazz);
        for (Field f : fields) {
            if (f.getName().equals(fieldName) && f.getAnnotation(EmbedList.class) != null) {
                result = true;
                break;
            }
        }
        return result;
    }

}