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/*
 * Copyright (C) 2008 feilong
 *
 * 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.feilong.core.bean;

import static com.feilong.core.DatePattern.COMMON_DATE_AND_TIME;
import static com.feilong.core.bean.ConvertUtil.convert;
import static com.feilong.core.bean.ToStringConfig.DEFAULT_CONNECTOR;

import java.math.BigDecimal;
import java.util.Calendar;
import java.util.Collection;
import java.util.Date;

import org.apache.commons.collections4.Transformer;

import com.feilong.core.lang.ClassUtil;
import com.feilong.core.util.transformer.DateToStringTransformer;
import com.feilong.core.util.transformer.NumberToStringTransformer;

/**
 * 处理值转换.
 *
 * @author feilong
 * @since 1.14.0
 */
public final class ToStringHandler{

    /** 默认的 日期转字符串转换器. */
    private static final Transformer   DEFAULT_DATETOSTRING_TRANSFORMER   = new DateToStringTransformer(COMMON_DATE_AND_TIME);

    /** 默认的 数字转字符串转换器. */
    private static final Transformer DEFAULT_NUMBERTOSTRING_TRANSFORMER = new NumberToStringTransformer(
                    com.feilong.core.NumberPattern.TWO_DECIMAL_POINTS);

    //---------------------------------------------------------------

    /** Don't let anyone instantiate this class. */
    private ToStringHandler(){
        //AssertionError不是必须的. 但它可以避免不小心在类的内部调用构造器. 保证该类在任何情况下都不会被实例化.
        //see 《Effective Java》 2nd
        throw new AssertionError("No " + getClass().getName() + " instances for you!");
    }

    //---------------------------------------------------------------

    /**
     * To string value.
     *
     * @param toBeConvertedValue
     *            the value
     * @return 如果 toBeConvertedValue 是null,返回 null

     *         如果 toBeConvertedValue 是 {@link CharSequence},直接 toString返回

     *         如果 toBeConvertedValue 是 数组,那么调用 {@link ConvertUtil#toString(Object[], String)}

     *         如果 toBeConvertedValue 是 {@link Collection},那么调用 {@link ConvertUtil#toString(Object[], String)}

     *         如果 toBeConvertedValue 是 {@link Date},那么返回 {@link com.feilong.core.DatePattern#COMMON_DATE_AND_TIME} 格式字符串

     *         如果 toBeConvertedValue 是 {@link BigDecimal}或者是{@link Float}或者是 {@link Double},那么返回
     *         {@link com.feilong.core.NumberPattern#TWO_DECIMAL_POINTS} 2 位小数点格式字符串

     *         其他调用 {@link com.feilong.core.bean.ConvertUtil#convert(Object, Class)}
     */
    static String toStringValue(Object toBeConvertedValue){
        if (null == toBeConvertedValue){
            return null;
        }

        //---------------------------------------------------------------
        //CharSequence
        //since 1.14.0
        if (ClassUtil.isInstance(toBeConvertedValue, CharSequence.class)){
            return ((CharSequence) toBeConvertedValue).toString();
        }

        //---------------------------------------------------------------

        //数组
        //since 1.14.0
        if (com.feilong.core.lang.ObjectUtil.isArray(toBeConvertedValue)){
            return ConvertUtil.toString((Object[]) toBeConvertedValue, DEFAULT_CONNECTOR);
        }

        //集合
        //since 1.14.0
        if (ClassUtil.isInstance(toBeConvertedValue, Collection.class)){
            return ConvertUtil.toString((Collection) toBeConvertedValue, DEFAULT_CONNECTOR);
        }

        //---------------------------------------------------------------
        //日期
        if (ClassUtil.isInstance(toBeConvertedValue, Date.class)){
            return DEFAULT_DATETOSTRING_TRANSFORMER.transform((Date) toBeConvertedValue);
        }
        //Calendar
        if (ClassUtil.isInstance(toBeConvertedValue, Calendar.class)){
            return DEFAULT_DATETOSTRING_TRANSFORMER.transform(((Calendar) toBeConvertedValue).getTime());
        }

        //---------------------------------------------------------------
        //数字
        if (ClassUtil.isInstanceAnyClass(toBeConvertedValue, BigDecimal.class, Double.class, Float.class)){
            return DEFAULT_NUMBERTOSTRING_TRANSFORMER.transform((Number) toBeConvertedValue);
        }

        //---------------------------------------------------------------
        return convert(toBeConvertedValue, String.class);
    }
}