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/*
 * Copyright 2014-2019 the original author or authors.
 *
 * 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 com.deepoove.poi.el;

import java.lang.reflect.Field;
import java.util.LinkedHashMap;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.deepoove.poi.config.Name;

/**
 * 寻找合适的属性，支持@Name注解
 * 
 * @author Sayi
 *
 */
class FieldFinder {
	private static Logger logger = LoggerFactory.getLogger(FieldFinder.class);

	private static LinkedHashMap, Field[]> cache = new LinkedHashMap, Field[]>(32, 0.75f, true) {

		private static final long serialVersionUID = -4306886008010847817L;

		protected boolean removeEldestEntry(java.util.Map.Entry, Field[]> eldest) {
			// TO DO 最大数可以被调整，如果是一个导出大量实体的业务，这个值应该增加来优化性能
			return size() > 20;
		};
	};

	static Field find(Class objClass, String key) {
		Class clazz = objClass;
		Field field = null;
		while (clazz != Object.class) {
			try {
				field = findInClazz(clazz, key);
				field.setAccessible(true);
				return field;
			} catch (NoSuchFieldException e) {
				// do nothing, go to super class
			} catch (Exception e) {
				logger.error("Error read the property:" + key + " from " + objClass);
			}
			clazz = clazz.getSuperclass();
		}
		return null;

	}

	static Field findInClazz(Class clazz, String key) throws NoSuchFieldException {
		Field field = null;
		try {
			field = clazz.getDeclaredField(key);
			return field;
		} catch (Exception e) {
		}

		Field[] fields = cache.get(clazz);
		if (null == fields) {
			fields = clazz.getDeclaredFields();
			cache.put(clazz, fields);
		}
		for (Field f : fields) {
			Name annotation = f.getAnnotation(Name.class);
			if (null != annotation && key.equals(annotation.value()))
				return f;
		}
		throw new NoSuchFieldException(key);
	}

}