 next
|
  Subject: Base64 decoder
Author: (Deleted User)
Date: 16 Sep 2009 03:47 AM
|
Good morning from the Netherlands,
I am now perfectly able to encode files to base64 format and upload them to an SQL application. This application is missing however an export functionality, so I am now trying to get the data from the database with an xquery and transform the base64 encoded field back to binary format.
I found this xsl sheet on the Internet, should I able to do the trick with this sheet? For now I am not able to run it due to a "no character data is allowed between top level elements", but I don't know what's the problem and searching on the Stylus form returns a system error since yesterday.
<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" />
<xsl:variable name="datamap" select="document('datamap.xml')" />
<xsl:template match="/">
<xsl:variable name="base64String1" select="'SGVsbG8gV29ybGQh'" />
<xsl:variable name="base64String2" select="'VGhpcyBpcyBiYXNlNjQgZW5jb2Rpbmc='" />
<xsl:variable name="base64String3" select="'Ymx1ZQ=='" />
<xsl:call-template name="convertBase64ToAscii">
<xsl:with-param name="base64String" select="$base64String1" />
</xsl:call-template>
<xsl:text>------------------------</xsl:text>
<xsl:call-template name="convertBase64ToAscii">
<xsl:with-param name="base64String" select="$base64String2" />
</xsl:call-template>
<xsl:text>------------------------</xsl:text>
<xsl:call-template name="convertBase64ToAscii">
<xsl:with-param name="base64String" select="$base64String3" />
</xsl:call-template>
<xsl:text>------------------------</xsl:text>
</xsl:template>
<!-- Template to convert the base64 string to ascii representation
-->
<xsl:template name="convertBase64ToAscii">
<xsl:param name="base64String" />
<!-- execute if last 2 characters do not contain = character
-->
<xsl:if test="not(contains(substring($base64String, string-length($base64String) - 1), '='))">
<xsl:variable name="binaryBase64String">
<xsl:call-template name="base64StringToBinary">
<xsl:with-param name="string" select="$base64String" />
</xsl:call-template>
</xsl:variable>
<xsl:call-template name="base64BinaryStringToAscii">
<xsl:with-param name="binaryString" select="$binaryBase64String" />
</xsl:call-template>
</xsl:if>
<!-- extract last two characters
-->
<xsl:variable name="secondLastChar" select="substring($base64String, string-length($base64String) - 1, 1)" />
<xsl:variable name="lastChar" select="substring($base64String, string-length($base64String), 1)" /> <!-- execute if 2nd last character is not a =, and last character is =
-->
<xsl:if test="($secondLastChar != '=') and ($lastChar = '=')">
<xsl:variable name="binaryBase64String">
<xsl:call-template name="base64StringToBinary">
<xsl:with-param name="string" select="substring($base64String, 1, string-length($base64String) - 4)" />
</xsl:call-template>
</xsl:variable>
<xsl:call-template name="base64BinaryStringToAscii">
<xsl:with-param name="binaryString" select="$binaryBase64String" />
</xsl:call-template>
<xsl:variable name="partialBinary">
<xsl:call-template name="base64StringToBinary">
<xsl:with-param name="string" select="substring($base64String, string-length($base64String) - 3, 3)" />
</xsl:call-template>
</xsl:variable>
<xsl:call-template name="base64BinaryStringToAscii">
<xsl:with-param name="binaryString" select="substring($partialBinary, 1, 8)" />
</xsl:call-template>
<xsl:call-template name="base64BinaryStringToAscii">
<xsl:with-param name="binaryString" select="substring($partialBinary, 9, 8)" />
</xsl:call-template>
</xsl:if>
<!-- execute if last 2 characters are both =
-->
<xsl:if test="($secondLastChar = '=') and ($lastChar = '=')">
<xsl:variable name="binaryBase64String">
<xsl:call-template name="base64StringToBinary">
<xsl:with-param name="string" select="substring($base64String, 1, string-length($base64String) - 4)" />
</xsl:call-template>
</xsl:variable>
- <xsl:call-template name="base64BinaryStringToAscii">
<xsl:with-param name="binaryString" select="$binaryBase64String" />
</xsl:call-template>
<xsl:variable name="partialBinary">
<xsl:call-template name="base64StringToBinary">
<xsl:with-param name="string" select="substring($base64String, string-length($base64String) - 3, 2)" />
</xsl:call-template>
</xsl:variable>
<xsl:call-template name="base64BinaryStringToAscii">
<xsl:with-param name="binaryString" select="substring($partialBinary, 1, 8)" />
</xsl:call-template>
</xsl:if>
</xsl:template>
<!-- Template to convert the base64 binary string to ascii representation
-->
<xsl:template name="base64BinaryStringToAscii">
<xsl:param name="binaryString" />
<xsl:if test="substring($binaryString, 1, 8) != ''">
<xsl:variable name="asciiDecimal">
<xsl:call-template name="binaryToDecimal">
<xsl:with-param name="binary" select="substring($binaryString, 1, 8)" />
<xsl:with-param name="sum" select="0" />
<xsl:with-param name="index" select="0" />
</xsl:call-template>
</xsl:variable>
<xsl:value-of select="$datamap/datamap/asciidecimal/char[decimal = $asciiDecimal]/ascii" />
<xsl:call-template name="base64BinaryStringToAscii">
<xsl:with-param name="binaryString" select="substring($binaryString, 9)" />
</xsl:call-template>
</xsl:if>
</xsl:template>
<!-- Template to convert a binary number to decimal representation; this template calls template pow
-->
<xsl:template name="binaryToDecimal">
<xsl:param name="binary" />
<xsl:param name="sum" />
<xsl:param name="index" />
<xsl:if test="substring($binary,string-length($binary) - 1) != ''">
<xsl:variable name="power">
<xsl:call-template name="pow">
<xsl:with-param name="m" select="2" />
<xsl:with-param name="n" select="$index" />
<xsl:with-param name="result" select="1" />
</xsl:call-template>
</xsl:variable>
<xsl:call-template name="binaryToDecimal">
<xsl:with-param name="binary" select="substring($binary, 1, string-length($binary) - 1)" />
<xsl:with-param name="sum" select="$sum + substring($binary,string-length($binary)) * $power" />
<xsl:with-param name="index" select="$index + 1" />
</xsl:call-template>
</xsl:if>
<xsl:if test="substring($binary,string-length($binary) - 1) = ''">
<xsl:value-of select="$sum" />
</xsl:if>
</xsl:template>
<!-- Template to calculate m to the power n
-->
<xsl:template name="pow">
<xsl:param name="m" />
<xsl:param name="n" />
<xsl:param name="result" />
<xsl:if test="$n >= 1">
<xsl:call-template name="pow">
<xsl:with-param name="m" select="$m" />
<xsl:with-param name="n" select="$n - 1" />
<xsl:with-param name="result" select="$result * $m" />
</xsl:call-template>
</xsl:if>
<xsl:if test="$n = 0">
<xsl:value-of select="$result" />
</xsl:if>
</xsl:template>
<!-- Template to convert a base64 string to binary representation; this template calls template decimalToBinary
-->
<xsl:template name="base64StringToBinary">
<xsl:param name="string" />
<xsl:if test="substring($string, 1, 1) != ''">
<xsl:variable name="binary">
<xsl:call-template name="decimalToBinary">
<xsl:with-param name="decimal" select="$datamap/datamap/decimalbase64/char[base64 = substring($string, 1, 1)]/value" />
<xsl:with-param name="prev" select="''" />
</xsl:call-template>
</xsl:variable>
<xsl:call-template name="padZeros">
<xsl:with-param name="string" select="$binary" />
<xsl:with-param name="no" select="6 - string-length($binary)" />
</xsl:call-template>
</xsl:if>
<xsl:if test="substring($string, 2) != ''">
<xsl:call-template name="base64StringToBinary">
<xsl:with-param name="string" select="substring($string, 2)" />
</xsl:call-template>
</xsl:if>
</xsl:template>
<!-- Template to left pad a binary string, with the specified no of 0s, to make it of length 6
-->
- <xsl:template name="padZeros">
<xsl:param name="string" />
<xsl:param name="no" />
<xsl:if test="$no > 0">
<xsl:call-template name="padZeros">
<xsl:with-param name="string" select="concat('0', $string)" />
<xsl:with-param name="no" select="6 - string-length($string) - 1" />
</xsl:call-template>
</xsl:if>
<xsl:if test="$no = 0">
<xsl:value-of select="$string" />
</xsl:if>
</xsl:template>
<!-- Template to convert a decimal number to binary representation
-->
<xsl:template name="decimalToBinary">
<xsl:param name="decimal" />
<xsl:param name="prev" />
<xsl:variable name="divresult" select="floor($decimal div 2)" />
<xsl:variable name="modresult" select="$decimal mod 2" />
<xsl:choose>
<xsl:when test="$divresult > 1">
<xsl:call-template name="decimalToBinary">
<xsl:with-param name="decimal" select="$divresult" />
<xsl:with-param name="prev" select="concat($modresult, $prev)" />
</xsl:call-template>
</xsl:when>
<xsl:when test="$divresult = 0">
<xsl:value-of select="concat($modresult, $prev)" />
</xsl:when>
<xsl:when test="$divresult = 1">
<xsl:text>1</xsl:text>
<xsl:value-of select="concat($modresult, $prev)" />
</xsl:when>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>
Thanks again,
Cynthia
|
|
top