com.feilong.core.text.NumberFormatUtil Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of feilong Show documentation
feilong is a suite of core and expanded libraries that include utility classes, http, excel,cvs, io classes, and much much more.
There is a newer version: 4.3.0
Show newest version
/*
 * 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.text;

import static com.feilong.core.lang.ObjectUtil.defaultIfNull;
import static java.math.RoundingMode.HALF_UP;

import java.math.RoundingMode;
import java.text.ChoiceFormat;
import java.text.DecimalFormat;
import java.text.Format;
import java.text.NumberFormat;

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

import com.feilong.core.NumberPattern;
import com.feilong.core.Validate;

/**
 * {@link NumberFormat}是所有数值格式的抽象基类,此类提供格式化和解析数值的接口.
 * 
 * 
 * 直接已知子类: {@link ChoiceFormat}, {@link DecimalFormat}.

 * 注意:{@link DecimalFormat}不是同步的 ,建议为每个线程创建独立的格式实例.(见JAVA API 文档)
 * 
 * 
 * @author feilong
 * @see Format
 * @see NumberFormat
 * @see DecimalFormat
 * @see NumberPattern
 * @since 1.0.2
 */
public final class NumberFormatUtil{

    /** The Constant LOGGER. */
    private static final Logger LOGGER = LoggerFactory.getLogger(NumberFormatUtil.class);

    /** Don't let anyone instantiate this class. */
    private NumberFormatUtil(){
        //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!");
    }

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

    /**
     * 将 {@link Number} 使用 {@link RoundingMode} numberPattern格式化.
     * 
     * 示例:
     * 
     * 
     * 
     *      * NumberFormatUtil.format(toBigDecimal(1.15), "#####.#",null)     =   1.2
     * NumberFormatUtil.format(toBigDecimal(1.25), "#####.#",null)     =   1.3
     * NumberFormatUtil.format(toBigDecimal(1.251), "#####.#",null)    =   1.3
     * 
     * NumberFormatUtil.format(toBigDecimal(-1.15), "#####.#",null)    =   -1.2
     * NumberFormatUtil.format(toBigDecimal(-1.25), "#####.#",null)    =   -1.3
     * NumberFormatUtil.format(toBigDecimal(-1.251), "#####.#",null)   =   -1.3
     * 
     * 
     * NumberFormatUtil.format(toBigDecimal(1.15), "#####.#", RoundingMode.HALF_EVEN)     =   1.2
     * NumberFormatUtil.format(toBigDecimal(1.25), "#####.#", RoundingMode.HALF_EVEN)     =   1.2
     * NumberFormatUtil.format(toBigDecimal(1.251), "#####.#", RoundingMode.HALF_EVEN)    =   1.3
     * 
     * NumberFormatUtil.format(toBigDecimal(-1.15), "#####.#", RoundingMode.HALF_EVEN)    =   -1.2
     * NumberFormatUtil.format(toBigDecimal(-1.25), "#####.#", RoundingMode.HALF_EVEN)    =   -1.2
     * NumberFormatUtil.format(toBigDecimal(-1.251), "#####.#", RoundingMode.HALF_EVEN)   =   -1.3
     * 
     * 
     * 
     * 
     * 关于参数 value:
     * 
     * 
     * 
     * 请尽量传递Integer,Long,BigDecimal,而不要使用 float,double等浮点类型,否则可能结果不准确,特别是jdk8以下的版本,具体参见
     * NumberFormatUtilTest 在 jdk8 下面测试不通过
     * 
     * 
     * 
     * 
     * 关于参数 roundingMode
     * 
     * 
     * 
     * 虽然{@link DecimalFormat},默认使用的是银行家舍入法 {@link RoundingMode#HALF_EVEN},参见
     * 关于 RoundingMode#HALF_EVEN
     * 
     * 
     * 
     * 但是我们常用标准的四舍五入,为了保持和 {@link com.feilong.core.lang.NumberUtil#toString(Number, String)}一致性,如果 roundingMode 为null,使用常用的
     * {@link RoundingMode#HALF_UP}来进行格式化
     * 
     * 
     * 
     * @param value
     *            the value
     * @param numberPattern
     *            格式化数字格式,可以参见或者使用{@link NumberPattern}
     * @param roundingMode
     *            舍入模式{@link RoundingMode},如果 为null,使用常用的 {@link RoundingMode#HALF_UP}
     * @return 如果 value 是null,抛出 {@link NullPointerException}

     *         如果 numberPattern 是null,抛出 {@link NullPointerException}

     *         如果 numberPattern 是blank,抛出 {@link IllegalArgumentException}

     * @see DecimalFormat
     * @see JAVA 8种舍入法
     */
    public static String format(Number value,String numberPattern,RoundingMode roundingMode){
        Validate.notNull(value, "value can't be null!");
        Validate.notBlank(numberPattern, "numberPattern can't be null!");

        //该构造方法内部 调用了applyPattern(pattern, false)
        DecimalFormat decimalFormat = new DecimalFormat(numberPattern);
        decimalFormat.setRoundingMode(defaultIfNull(roundingMode, HALF_UP));

        String result = decimalFormat.format(value);

        if (LOGGER.isTraceEnabled()){
            String message = "input:[{}],with:[{}]=[{}],localizedPattern:[{}]";
            LOGGER.trace(message, value, numberPattern, result, decimalFormat.toLocalizedPattern());
        }
        return result;
    }
}
com.feilong.core.text.NumberFormatUtil Maven / Gradle / Ivy

示例:

关于参数 `value`:

关于参数 `roundingMode`
