svfractionalformat.java

Office格式转换代码

/*
 *  ====================================================================
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2003 The Apache Software Foundation.  All rights
 *  reserved.
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 *  if any, must include the following acknowledgment:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
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package org.apache.poi.hssf.contrib.view;

import java.text.*;

/**
 * This class is used to format cells into their fractional format.
 *
 * I cant be 100% sure that the same fractional value will be displayed as in
 * excel but then again it is a lossy formating mode anyway
 *
 * @author     Jason Height
 * @created    15 July 2002
 */
public class SVFractionalFormat extends Format {
  private short ONE_DIGIT = 1;
  private short TWO_DIGIT = 2;
  private short THREE_DIGIT = 3;
  private short UNITS = 4;
  private int units = 1;
  private short mode = -1;

  /** Constructs a new FractionalFormatter
   *
   *  The formatStr defines how the number will be formatted
   *  # ?/? Up to one digit
   *  # ??/?? Up to two digits
   *  # ???/??? Up to three digits
   *  # ?/2 In halves
   *  # ?/4 In quarters
   *  # ?/8 In eighths
   *  # ?/16 In sixteenths
   *  # ?/10 In tenths
   *  # ?/100 In hundredths
   */
  public SVFractionalFormat(String formatStr) {
    if ("# ?/?".equals(formatStr))
      mode = ONE_DIGIT;
    else if ("# ??/??".equals(formatStr))
      mode = TWO_DIGIT;
    else if ("# ???/???".equals(formatStr))
      mode = THREE_DIGIT;
    else if ("# ?/2".equals(formatStr)) {
      mode = UNITS;
      units = 2;
    } else if ("# ?/4".equals(formatStr)) {
      mode = UNITS;
      units = 4;
    } else if ("# ?/8".equals(formatStr)) {
      mode = UNITS;
      units = 8;
    } else if ("# ?/16".equals(formatStr)) {
      mode = UNITS;
      units = 16;
    } else if ("# ?/10".equals(formatStr)) {
      mode = UNITS;
      units = 10;
    } else if ("# ?/100".equals(formatStr)) {
      mode = UNITS;
      units = 100;
    }
  }

  /**
   *  Returns a fractional string representation of a double to a maximum denominator size
   *
   * This code has been translated to java from the following web page.
   * http://www.codeproject.com/cpp/fraction.asp
   * Originally coded in c++ By Dean Wyant  [e-mail]
   * The code on the web page is freely available.
   *
   * @param  f       Description of the Parameter
   * @param  MaxDen  Description of the Parameter
   * @return         Description of the Return Value
   */
  private String format(final double f, final int MaxDen) {
    long Whole = (long)f;
    int sign = 1;
    if (f < 0) {
      sign = -1;
    }
    double Precision = 0.00001;
    double AllowedError = Precision;
    double d = Math.abs(f);
    d -= Whole;
    double Frac = d;
    double Diff = Frac;
    long Num = 1;
    long Den = 0;
    long A = 0;
    long B = 0;
    long i = 0;
    if (Frac > Precision) {
      while (true) {
        d = 1.0 / d;
        i = (long) (d + Precision);
        d -= i;
        if (A > 0) {
          Num = i * Num + B;
        }
        Den = (long) (Num / Frac + 0.5);
        Diff = Math.abs((double) Num / Den - Frac);
        if (Den > MaxDen) {
          if (A > 0) {
            Num = A;
            Den = (long) (Num / Frac + 0.5);
            Diff = Math.abs((double) Num / Den - Frac);
          } else {
            Den = MaxDen;
            Num = 1;
            Diff = Math.abs((double) Num / Den - Frac);
            if (Diff > Frac) {
              Num = 0;
              Den = 1;
              // Keeps final check below from adding 1 and keeps Den from being 0
              Diff = Frac;
            }
          }
          break;
        }
        if ((Diff <= AllowedError) || (d < Precision)) {
          break;
        }
        Precision = AllowedError / Diff;
        // This calcualtion of Precision does not always provide results within
        // Allowed Error. It compensates for loss of significant digits that occurs.
        // It helps to round the inprecise reciprocal values to i.
        B = A;
        A = Num;
      }
    }
    if (Num == Den) {
      Whole++;
      Num = 0;
      Den = 0;
    } else if (Den == 0) {
      Num = 0;
    }
    if (sign < 0) {
      if (Whole == 0) {
        Num = -Num;
      } else {
        Whole = -Whole;
      }
    }
    return new StringBuffer().append(Whole).append(" ").append(Num).append("/").append(Den).toString();
  }

  /** This method formats the double in the units specified.
   *  The usints could be any number but in this current implementation it is
   *  halves (2), quaters (4), eigths (8) etc
   */
  private String formatUnit(double f, int units) {
    long Whole = (long)f;
    f -= Whole;
    long Num = Math.round(f * units);

    return new StringBuffer().append(Whole).append(" ").append(Num).append("/").append(units).toString();
  }

  public final String format(double val) {
    if (mode == ONE_DIGIT) {
      return format(val, 9);
    } else if (mode == TWO_DIGIT) {
      return format(val, 99);
    } else if (mode == THREE_DIGIT) {
      return format(val, 999);
    } else if (mode == UNITS) {
      return formatUnit(val , units);
    }
    throw new RuntimeException("Unexpected Case");
  }

  public StringBuffer format(Object obj,
                                      StringBuffer toAppendTo,
                                      FieldPosition pos) {
    if (obj instanceof Number) {
      toAppendTo.append(format(((Number)obj).doubleValue()));
      return toAppendTo;
    }
    else throw new IllegalArgumentException("Can only handle Numbers");
  }

  public Object parseObject(String source,
                                   ParsePosition status) {
    //JMH TBD
    return null;
  }

  public Object parseObject(String source)
                   throws ParseException {
    //JMH TBD
    return null;
  }

  public Object clone() {
    //JMH TBD
    return null;
  }


}