FormattedStringToNumber.java :  » J2EE » spring-ide_2.3.0 » org » springframework » binding » convert » converters » Java Open Source

/*
 * Copyright 2004-2008 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 org.springframework.binding.convert.converters;

import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.Locale;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.binding.format.DefaultNumberFormatFactory;
import org.springframework.binding.format.NumberFormatFactory;
import org.springframework.util.NumberUtils;

/**
 * A converter for common number types such as integers and big decimals. Allows the configuration of an explicit number
 * pattern and locale.
 * 
 * Works with a general purpose {@link DecimalFormat} instance returned by calling
 * {@link NumberFormat#getInstance(Locale)} by default. This instance supports parsing any number type generally and
 * will not perform special type-specific logic such as rounding or truncation. Subclasses may override.
 * 
 * Will coerse parsed Numbers to the desired numberClass as necessary. If type-coersion results in an overflow
 * condition; for example, what can occur with a Long being coersed to a Short, an exception will be thrown.
 * 
 * @see NumberFormat
 * @see DecimalFormat
 * 
 * @author Keith Donald
 */
public class FormattedStringToNumber extends StringToObject {

  private static Log logger = LogFactory.getLog(FormattedStringToNumber.class);

  private NumberFormatFactory numberFormatFactory = new DefaultNumberFormatFactory();

  private boolean lenient;

  public FormattedStringToNumber() {
    super(Number.class);
  }

  public FormattedStringToNumber(Class numberClass) {
    super(numberClass);
  }

  /**
   * Sets the factory that returns the {@link NumberFormat} instance that will format numbers handled by this
   * converter.
   * @param numberFormatFactory the number format factory
   */
  public void setNumberFormatFactory(NumberFormatFactory numberFormatFactory) {
    this.numberFormatFactory = numberFormatFactory;
  }

  /**
   * If this Converter is "lenient" in parsing number strings. A lenient converter does not require that all
   * characters in the String be parsed successfully. Default is false.
   * @return the lenient flag
   */
  public boolean getLenient() {
    return lenient;
  }

  /**
   * Sets if this Converter should parse leniently.
   * @param lenient the lenient flag
   */
  public void setLenient(boolean lenient) {
    this.lenient = lenient;
  }

  protected Object toObject(String string, Class targetClass) throws Exception {
    ParsePosition parsePosition = new ParsePosition(0);
    NumberFormat format = numberFormatFactory.getNumberFormat();
    Number number = format.parse(string, parsePosition);
    if (number == null) {
      // no object could be parsed
      throw new InvalidFormatException(string, getPattern(format));
    }
    if (!lenient) {
      if (string.length() != parsePosition.getIndex()) {
        // indicates a part of the string that was not parsed; e.g. ".5" in 1234.5 when parsing an Integer
        throw new InvalidFormatException(string, getPattern(format));
      }
    }
    return convertToNumberClass(number, targetClass);
  }

  protected String toString(Object object) throws Exception {
    Number number = (Number) object;
    return numberFormatFactory.getNumberFormat().format(number);
  }

  /**
   * Coerces the Number object returned by NumberFormat to the desired numberClass. Subclasses may override.
   * @param number the parsed number
   * @return the coersed number
   * @throws IllegalArgumentException when an overflow condition occurs during coersion
   */
  protected Number convertToNumberClass(Number number, Class numberClass) throws IllegalArgumentException {
    return NumberUtils.convertNumberToTargetClass(number, numberClass);
  }

  // internal helpers

  private String getPattern(NumberFormat format) {
    if (format instanceof DecimalFormat) {
      return ((DecimalFormat) format).toPattern();
    } else {
      logger.warn("Pattern string cannot be determined because NumberFormat is not a DecimalFormat");
      return "defaultNumberFormatInstance";
    }
  }
}