utilstring.java

TinySQL是一个轻量级的纯java数据库引擎

/*
 * This class provides string manipulation methods.
 *
 * $Author: davis $
 * $Date: 2004/12/18 21:23:31 $
 * $Revision: 1.1 $
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 * Revision History:
 *
 * Written by Davis Swan in February, 2004.
 */
package com.sqlmagic.tinysql;

import java.text.*;
import java.util.*;
import java.lang.*;
import java.sql.Types;

public class UtilString
{
/*
 * Is this a quoted string?
 */
   public static boolean isQuotedString(String inputString)
   {
      String trimString;
      int trimLength;
      if ( inputString == (String)null ) return false;
      trimString = inputString.trim();
      trimLength = trimString.length();
      if ( trimString.length() == 0 ) return false;
      if ( ( trimString.charAt(0) == '\'' &
             trimString.charAt(trimLength - 1) == '\'' ) |
           ( trimString.charAt(0) == '"' & 
             trimString.charAt(trimLength - 1) == '"' ) )
      {
         return true;
      }
      return false;
   }
/*
 * Remove enclosing quotes from a string.
 */
   public static String removeQuotes(String inputString)
   {
      String trimString;
      int trimLength;
      if ( inputString == (String)null ) return inputString;
      trimString = inputString.trim();
      trimLength = trimString.length();
      if ( trimString.length() == 0 ) return inputString;
      if ( ( trimString.charAt(0) == '\'' &
             trimString.charAt(trimLength - 1) == '\'' ) |
           ( trimString.charAt(0) == '"' & 
             trimString.charAt(trimLength - 1) == '"' ) )
      {
         return trimString.substring(1,trimString.length() - 1);
      }
      return inputString;
   }
/*
 * Convert a string to a double or return a default value.
 */
   public static double doubleValue(String inputString)
   {
      return doubleValue(inputString,Double.MIN_VALUE);
   }
   public static double doubleValue(String inputString,double defaultValue )
   {
      try
      {
         return Double.parseDouble(inputString);
      } catch (Exception e) {
         return defaultValue;
      }
   }
/*
 * Convert a date string in the format YYYYMMDD to the standard
 * date output YYYY-MM-DD
 */
   public static String toStandardDate(String inputDateString)
     throws tinySQLException
   {
      String dateString,stdDateString;
      int month;
      if ( inputDateString == (String)null )
         throw new tinySQLException ("Cannot format NULL date");
      if ( inputDateString.length() < 8 )
         throw new tinySQLException("Date " + inputDateString
         + " not in YYYYMMDD format");
/*
 *    Convert the input to YYYYMMDD - this is required because 
 *    versions of tinySQL before 2.26d incorrectly stored dates in several
 *    different character string representations.
 */
      dateString = dateValue(inputDateString);
      stdDateString = dateString.substring(0,4) + "-" 
      + dateString.substring(4,6) + "-"
      + dateString.substring(6,8); 
      return stdDateString;
   }
/*
 * Convert a date string in the format DD-MON-YY, DD-MON-YYYY, or YYYYMMDD
 * to the output YYYYMMDD after checking the validity of all subfields. 
 * A tinySQLException is thrown if there are problems.
 */
   public static String dateValue(String inputString ) throws tinySQLException
   {
      String months = "-JAN-FEB-MAR-APR-MAY-JUN-JUL-AUG-SEP-OCT-NOV-DEC-";
      int[] daysInMonth = {31,29,31,30,31,30,31,31,30,31,30,31};
      String dateString,dayField,monthName,monthField,yearField;
      String[] ftFields;
      FieldTokenizer ft;
      int year,month,day,monthAt;
      dateString = inputString.toUpperCase().trim();
      if ( dateString.length() < 8 ) 
         throw new tinySQLException(dateString + " is less than 8 characters.");
/*
 *    Check for YYYY-MM-DD format - convert to YYYYMMDD if found.
 */
      if ( dateString.length() == 10 & dateString.charAt(4) == '-' &
           dateString.charAt(7) == '-' )
      {
         dateString = dateString.substring(0,4) + dateString.substring(5,7)
         + dateString.substring(8,10);
      }
/*
 *    First check for an 8 character field properly formatted.
 */
      if ( dateString.length() == 8 & isInteger(dateString) )
      {
         try
         {
            year = Integer.parseInt(dateString.substring(0,4));
            if ( year < 0 | year > 2100 ) 
               throw new tinySQLException(dateString + " year not " 
               + "recognized.");
            month = Integer.parseInt(dateString.substring(4,6));
            if ( month < 1 | month > 12 ) 
               throw new tinySQLException(dateString + " month not " 
               + "recognized.");
            day = Integer.parseInt(dateString.substring(6,8));
            if ( day < 1 | day > daysInMonth[month-1] ) 
               throw new tinySQLException(dateString + " day not " 
               + "recognized.");
            return dateString;
         } catch ( Exception dateEx ) {
            throw new tinySQLException( dateEx.getMessage());
         }
      }
/*
 *    Check for dd-MON-YY formats - strip off TO_DATE if it exists.
 */
      if ( dateString.startsWith("TO_DATE") )
      {
         dateString = dateString.substring(8,dateString.length()-1);
         dateString = removeQuotes(dateString);
      }
      ft = new FieldTokenizer(dateString,'-',false);
      ftFields = ft.getFields();
      if ( ftFields.length < 3 )
      { 
         throw new tinySQLException(dateString + " is not a date with "
         + "format DD-MON-YY!");
      } else {
         try 
         {
            day = Integer.parseInt(ftFields[0]);
            monthName = ftFields[1];
            monthAt = months.indexOf("-" + monthName + "-");
            if ( monthAt == -1 )
               throw new tinySQLException(dateString + " month not " 
               + "recognized.");
            month = (monthAt + 4)/4;
            if ( day < 1 | day > daysInMonth[month-1] )
               throw new tinySQLException(dateString + " day not " 
               + "between 1 and " + daysInMonth[month-1]);
            year = Integer.parseInt(ftFields[2]);
            if ( year < 0 | year > 2100 ) 
               throw new tinySQLException(dateString + " year not " 
               + "recognized.");
/*
 *          Assume that years < 50 are in the 21st century, otherwise 
 *          the 20th.
 */
            if ( year < 50 ) year = 2000 + year;
            else year = 1900 + year;
            dayField = Integer.toString(day);
            if ( dayField.length() < 2 ) dayField = "0" + dayField;
            monthField = Integer.toString(month);
            if ( monthField.length() < 2 ) monthField = "0" + monthField;
            yearField = Integer.toString(year);
            return yearField + monthField + dayField; 
         } catch (Exception dayEx ) {
            throw new tinySQLException(dateString + " exception " 
            + dayEx.getMessage());
         }
      }
   }
/*
 * The following method replaces all occurrences of oldString with newString
 * in the inputString.  This function can be replaced with the native
 * String method replaceAll in JDK 1.4 and above but is provide to support
 * earlier versions of the JRE.
 */
   public static String replaceAll(String inputString,String oldString,
      String newString)
   {
      StringBuffer outputString = new StringBuffer(100);
      int startIndex=0,nextIndex;
      while ( inputString.substring(startIndex).indexOf(oldString) > -1 )
      {
         nextIndex = startIndex + inputString.substring(startIndex).indexOf(oldString);
         if ( nextIndex > startIndex )
         { 
            outputString.append(inputString.substring(startIndex,nextIndex));
         }
         outputString.append(newString);
         startIndex = nextIndex + oldString.length();
      }
      if ( startIndex <= inputString.length() - 1 )
      {
         outputString.append(inputString.substring(startIndex));
      }
      return outputString.toString();