numberconverter.java

APACHE 公司出的java bean 工具包

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.beanutils.converters;

import java.util.Calendar;
import java.util.Date;
import java.util.Locale;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.NumberFormat;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.ParsePosition;

import org.apache.commons.beanutils.ConversionException;

/**
 * {@link org.apache.commons.beanutils.Converter} implementaion that handles conversion
 * to and from <b>java.lang.Number</b> objects.
 * <p>
 * This implementation handles conversion for the following
 * <code>java.lang.Number</code> types.
 * <ul>
 *     <li><code>java.lang.Byte</code></li>
 *     <li><code>java.lang.Short</code></li>
 *     <li><code>java.lang.Integer</code></li>
 *     <li><code>java.lang.Long</code></li>
 *     <li><code>java.lang.Float</code></li>
 *     <li><code>java.lang.Double</code></li>
 *     <li><code>java.math.BigDecimal</code></li>
 *     <li><code>java.math.BigInteger</code></li>
 * </ul>
 *
 * <h3>String Conversions (to and from)</h3>
 * This class provides a number of ways in which number
 * conversions to/from Strings can be achieved:
 * <ul>
 *    <li>Using the default format for the default Locale, configure using:</li>
 *        <ul>
 *           <li><code>setUseLocaleFormat(true)</code></li>
 *        </ul>
 *    <li>Using the default format for a specified Locale, configure using:</li>
 *        <ul>
 *           <li><code>setLocale(Locale)</code></li>
 *        </ul>
 *    <li>Using a specified pattern for the default Locale, configure using:</li>
 *        <ul>
 *           <li><code>setPattern(String)</code></li>
 *        </ul>
 *    <li>Using a specified pattern for a specified Locale, configure using:</li>
 *        <ul>
 *           <li><code>setPattern(String)</code></li>
 *           <li><code>setLocale(Locale)</code></li>
 *        </ul>
 *    <li>If none of the above are configured the
 *        <code>toNumber(String)</code> method is used to convert
 *        from String to Number and the Number's
 *        <code>toString()</code> method used to convert from
 *        Number to String.</li>
 * </ul>
 *
 * <p>
 * <strong>N.B.</strong>Patterns can only be specified used the <i>standard</i>
 * pattern characters and NOT in <i>localized</i> form (see <code>java.text.SimpleDateFormat</code>).
 * For example to cater for number styles used in Germany such as <code>0.000,00</code> the pattern
 * is specified in the normal form <code>0,000.00</code> and the locale set to <code>Locale.GERMANY</code>.
 *
 * @version $Revision: 555845 $ $Date: 2007-07-13 03:52:05 +0100 (Fri, 13 Jul 2007) $
 * @since 1.8.0
 */
public class NumberConverter extends AbstractConverter {

    private static final Integer ZERO = new Integer(0);
    private static final Integer ONE  = new Integer(1);

    private String pattern;
    private boolean allowDecimals;
    private boolean useLocaleFormat;
    private Locale locale;

    // ----------------------------------------------------------- Constructors

    /**
     * Construct a <b>java.lang.Number</b> <i>Converter</i>
     * that throws a <code>ConversionException</code> if a error occurs.
     *
     * @param defaultType The default type this <code>Converter</code>
     * handles
     * @param allowDecimals Indicates whether decimals are allowed
     */
    public NumberConverter(Class defaultType, boolean allowDecimals) {
        super(defaultType);
        this.allowDecimals = allowDecimals;
    }

    /**
     * Construct a <code>java.lang.Number</code> <i>Converter</i> that returns
     * a default value if an error occurs.
     *
     * @param defaultType The default type this <code>Converter</code>
     * handles
     * @param allowDecimals Indicates whether decimals are allowed
     * @param defaultValue The default value to be returned
     */
    public NumberConverter(Class defaultType, boolean allowDecimals, Object defaultValue) {
        super(defaultType);
        this.allowDecimals = allowDecimals;
        setDefaultValue(defaultValue);
    }

    // --------------------------------------------------------- Public Methods

    /**
     * Return whether decimals are allowed in the number.
     *
     * @return Whether decimals are allowed in the number
     */
    public boolean isAllowDecimals() {
        return allowDecimals;
    }

    /**
     * Set whether a format should be used to convert
     * the Number.
     *
     * @param useLocaleFormat <code>true</code> if a number format
     * should be used.
     */
    public void setUseLocaleFormat(boolean useLocaleFormat) {
        this.useLocaleFormat = useLocaleFormat;
    }

    /**
     * Return the number format pattern used to convert
     * Numbers to/from a <code>java.lang.String</code>
     * (or <code>null</code> if none specified).
     * <p>
     * See <code>java.text.SimpleDateFormat</code> for details
     * of how to specify the pattern.
     *
     * @return The format pattern.
     */
    public String getPattern() {
        return pattern;
    }

    /**
     * Set a number format pattern to use to convert
     * Numbers to/from a <code>java.lang.String</code>.
     * <p>
     * See <code>java.text.SimpleDateFormat</code> for details
     * of how to specify the pattern.
     *
     * @param pattern The format pattern.
     */
    public void setPattern(String pattern) {
        this.pattern = pattern;
        setUseLocaleFormat(true);
    }

    /**
     * Return the Locale for the <i>Converter</i>
     * (or <code>null</code> if none specified).
     *
     * @return The locale to use for conversion
     */
    public Locale getLocale() {
        return locale;
    }

    /**
     * Set the Locale for the <i>Converter</i>.
     *
     * @param locale The locale to use for conversion
     */
    public void setLocale(Locale locale) {
        this.locale = locale;
        setUseLocaleFormat(true);
    }

    // ------------------------------------------------------ Protected Methods

    /**
     * Convert an input Number object into a String.
     *
     * @param value The input value to be converted
     * @return the converted String value.
     * @throws Throwable if an error occurs converting to a String
     */
    protected String convertToString(Object value) throws Throwable {

        String result = null;
        if (useLocaleFormat && value instanceof Number) {
            NumberFormat format = getFormat();
            format.setGroupingUsed(false);
            result = format.format(value);
            if (log().isDebugEnabled()) {
                log().debug("    Converted  to String using format '" + result + "'");
            }

        } else {
            result = value.toString();
            if (log().isDebugEnabled()) {
                log().debug("    Converted  to String using toString() '" + result + "'");
            }
        }
        return result;

    }

    /**
     * Convert the input object into a Number object of the
     * specified type.
     *
     * @param targetType Data type to which this value should be converted.
     * @param value The input value to be converted.
     * @return The converted value.
     * @throws Throwable if an error occurs converting to the specified type
     */
    protected Object convertToType(Class targetType, Object value) throws Throwable {

        Class sourceType = value.getClass();
        // Handle Number
        if (value instanceof Number) {
            return toNumber(sourceType, targetType, (Number)value);
        }

        // Handle Boolean
        if (value instanceof Boolean) {
            return toNumber(sourceType, targetType, ((Boolean)value).booleanValue() ? ONE : ZERO);
        }

        // Handle Date --> Long
        if (value instanceof Date && Long.class.equals(targetType)) {
            return new Long(((Date)value).getTime());
        }

        // Handle Calendar --> Long
        if (value instanceof Calendar  && Long.class.equals(targetType)) {
            return new Long(((Calendar)value).getTime().getTime());
        }

        // Convert all other types to String & handle
        String stringValue = value.toString().trim();
        if (stringValue.length() == 0) {
            return handleMissing(targetType);
        }

        // Convert/Parse a String
        Number number = null;
        if (useLocaleFormat) {
            NumberFormat format = getFormat();
            number = parse(sourceType, targetType, stringValue, format);
        } else {
            if (log().isDebugEnabled()) {
                log().debug("    No NumberFormat, using default conversion");
            }
            number = toNumber(sourceType, targetType, stringValue);
        }

        // Ensure the correct number type is returned
        return toNumber(sourceType, targetType, number);

    }

    /**
     * Convert any Number object to the specified type for this