Java tutorial
package org.springframework.data.simpledb.attributeutil; /** * ***************************************************************************** * Copyright 2007 Amazon Technologies, Inc. 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://aws.amazon.com/apache2.0 This file 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. * ***************************************************************************** __ _ _ ___ ( )( \/\/ )/ __) /__\ \ / \__ \ (_)(_) \/\/ (___/ * * Amazon Simple DB Java Library API Version: 2007-11-07 Generated: Fri Jan 18 01:13:17 PST 2008 * */ import java.io.UnsupportedEncodingException; import java.math.BigDecimal; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; import java.util.TimeZone; import org.apache.commons.codec.binary.Base64; import org.springframework.data.mapping.model.MappingException; /** * Provides collection of static functions for conversion of various values into strings that may be compared * lexicographically. * */ public final class AmazonSimpleDBUtil { private static final String UTC_TZ_ID = "UTC"; /** * static value hardcoding date format used for conversation of Date into String */ private static String dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"; private static final int LONG_DIGITS = 20; private static final BigDecimal OFFSET_VALUE = new BigDecimal(Long.MIN_VALUE).negate(); private static final String UTF8_ENCODING = "UTF-8"; private static final int BASE = 10; private static final int ENCODE_DATE_COLONS_INDEX = 2; private static final int DECODE_DATE_COLONS_INDEX = 3; private AmazonSimpleDBUtil() { /* utility class */ } /** * Unsed to encode an Integer {@link Number}. */ public static String encodeAsIntegerNumber(Object ob) { BigDecimal integerBigDecimal = AmazonSimpleDBUtil.tryToStoreAsIntegerBigDecimal(ob); if (integerBigDecimal != null) { return AmazonSimpleDBUtil.encodeRealNumberRange(integerBigDecimal, AmazonSimpleDBUtil.LONG_DIGITS, OFFSET_VALUE); } return null; } public static BigDecimal decodeIntegerNumber(String value) { return AmazonSimpleDBUtil.decodeRealNumberRange(value, OFFSET_VALUE); } /** * Unsed to encode a Not Integer {@link Number}. */ public static String encodeAsRealNumber(Object ob) { if (AmazonSimpleDBUtil.isNaN(ob) || AmazonSimpleDBUtil.isInfinite(ob)) { throw new MappingException("Could not serialize NaN or Infinity values"); } BigDecimal realBigDecimal = AmazonSimpleDBUtil.tryToStoreAsRealBigDecimal(ob); if (realBigDecimal != null) { return AmazonSimpleDBUtil.encodeRealNumberRange(realBigDecimal, AmazonSimpleDBUtil.LONG_DIGITS, AmazonSimpleDBUtil.LONG_DIGITS, OFFSET_VALUE); } return null; } public static BigDecimal decodeRealNumber(String value) { if (value.matches(".*Infinity|NaN")) { throw new MappingException("Could not serialize NaN or Infinity values"); } return AmazonSimpleDBUtil.decodeRealNumberRange(value, AmazonSimpleDBUtil.LONG_DIGITS, OFFSET_VALUE); } public static String encodeRealNumberRange(BigDecimal number, int maxNumDigits, BigDecimal offsetValue) { final BigDecimal offsetNumber = number.add(offsetValue); final String longString = offsetNumber.toString(); final int numZeroes = maxNumDigits - longString.length(); final int paddedSize = numZeroes + longString.length(); final StringBuilder strBuffer = new StringBuilder(paddedSize); for (int i = 0; i < numZeroes; i++) { strBuffer.insert(i, '0'); } strBuffer.append(longString); return strBuffer.toString(); } public static String encodeRealNumberRange(BigDecimal number, int maxDigitsLeft, int maxDigitsRight, BigDecimal offsetValue) { BigDecimal shiftMultiplier = new BigDecimal(Math.pow(BASE, maxDigitsRight)); BigDecimal shiftedNumber = number.multiply(shiftMultiplier); shiftedNumber = shiftedNumber.setScale(0, BigDecimal.ROUND_HALF_UP); final BigDecimal shiftedOffset = offsetValue.multiply(shiftMultiplier); final BigDecimal offsetNumber = shiftedNumber.add(shiftedOffset); String longString = offsetNumber.toString(); final int numBeforeDecimal = longString.length(); final int numZeroes = maxDigitsLeft + maxDigitsRight - numBeforeDecimal; final int paddedSize = numZeroes + longString.length(); final StringBuilder strBuffer = new StringBuilder(paddedSize); for (int i = 0; i < numZeroes; i++) { strBuffer.insert(i, '0'); } strBuffer.append(longString); return strBuffer.toString(); } public static BigDecimal decodeRealNumberRange(String value, BigDecimal offsetValue) { BigDecimal offsetNumber = new BigDecimal(value); return (offsetNumber.subtract(offsetValue)); } public static BigDecimal decodeRealNumberRange(String value, int maxDigitsRight, BigDecimal offsetValue) { BigDecimal offsetNumber = new BigDecimal(value); BigDecimal shiftMultiplier = new BigDecimal(Math.pow(BASE, maxDigitsRight)); BigDecimal tempVal0 = offsetValue.multiply(shiftMultiplier); BigDecimal tempVal = (offsetNumber.subtract(tempVal0)); return (tempVal.divide(shiftMultiplier)); } /** * Encodes date value into string format that can be compared lexicographically * * @param date * date value to be encoded * @return string representation of the date value */ public static String encodeDate(Date date) { SimpleDateFormat dateFormatter = new SimpleDateFormat(dateFormat); dateFormatter.setTimeZone(TimeZone.getTimeZone(UTC_TZ_ID)); /* Java doesn't handle ISO8601 nicely: need to add ':' manually */ String result = dateFormatter.format(date); return result.substring(0, result.length() - ENCODE_DATE_COLONS_INDEX) + ":" + result.substring(result.length() - ENCODE_DATE_COLONS_INDEX); } /** * Decodes date value from the string representation created using encodeDate(..) function. * * @param value * string representation of the date value * @return original date value */ public static Date decodeDate(String value) throws ParseException { String javaValue = value.substring(0, value.length() - DECODE_DATE_COLONS_INDEX) + value.substring(value.length() - ENCODE_DATE_COLONS_INDEX); SimpleDateFormat dateFormatter = new SimpleDateFormat(dateFormat); dateFormatter.setTimeZone(TimeZone.getTimeZone(UTC_TZ_ID)); return dateFormatter.parse(javaValue); } /** * Encodes byteArray value into a base64-encoded string. * * @return string representation of the date value */ public static String encodeByteArray(byte[] byteArray) { try { return new String(Base64.encodeBase64(byteArray), UTF8_ENCODING); } catch (UnsupportedEncodingException e) { throw new MappingException("Could not encode byteArray to UTF8 encoding", e); } } /** * Decodes byte[] value from the string representation created using encodeDate(..) function. * * @param value * string representation of the date value * @return original byte[] value */ public static byte[] decodeByteArray(String value) throws ParseException { try { return Base64.decodeBase64(value.getBytes(UTF8_ENCODING)); } catch (UnsupportedEncodingException e) { throw new MappingException("Could not decode byteArray to UTF8 encoding", e); } } private static BigDecimal tryToStoreAsRealBigDecimal(Object ob) { BigDecimal bigDecimal = null; if (canBeStoredAsRealBigDecimal(ob)) { bigDecimal = new BigDecimal(ob.toString()); } else if (ob instanceof BigDecimal) { bigDecimal = (BigDecimal) ob; } return bigDecimal; } private static BigDecimal tryToStoreAsIntegerBigDecimal(Object ob) { BigDecimal bigDecimal = null; if (canBeStoredAsIntegerBigDecimal(ob)) { bigDecimal = new BigDecimal(ob.toString()); } return bigDecimal; } private static boolean canBeStoredAsRealBigDecimal(Object ob) { if (isNaN(ob) || isInfinite(ob)) { return false; } return ob instanceof Double || ob instanceof Float; } private static boolean canBeStoredAsIntegerBigDecimal(Object ob) { return ob instanceof Number && !(ob instanceof Float || ob instanceof Double); } public static boolean isNaN(Object ob) { return (ob instanceof Double && ((Double) ob).isNaN()) || (ob instanceof Float && ((Float) ob).isNaN()); } public static boolean isInfinite(Object ob) { return (ob instanceof Double && ((Double) ob).isInfinite()) || (ob instanceof Float && ((Float) ob).isInfinite()); } }