我知道有很多PDF提取方法/技术，但我正在为PHP中的PDF提供可靠的文本提取器。我想要的只是提取单词，而不是数字而不是特殊字符。
实现这一目标的任何坚实技术的想法？
答案 0 :(得分：2)
Zend Framework提供了Zend_Pdf，一个将加载和解析pdf文档的php类。
Here is a script，显示如何从加载的Zend_Pdf对象中提取文本。
答案 1 :(得分：0)
如果您使用laravel，可以尝试我的图书馆...
<?php
namespace App\Helpers;
/*
SYNTAX:
include('class.pdf2text.php');
$a = new PDF2Text();
$a->setFilename('test.pdf');
$a->decodePDF();
echo $a->output();
*/
class PDF2Text {
// Some settings
var $multibyte = 4; // Use setUnicode(TRUE|FALSE)
var $convertquotes = ENT_QUOTES; // ENT_COMPAT (double-quotes), ENT_QUOTES (Both), ENT_NOQUOTES (None)
var $showprogress = false; // TRUE if you have problems with time-out
// Variables
var $filename = '';
var $decodedtext = '';
function setFilename($filename) {
$this->decodedtext = '';
$this->filename = $filename;
}
function output($echo = false) {
if($echo) echo $this->decodedtext;
else return $this->decodedtext;
}
function setUnicode($input) {
// 4 for unicode. But 2 should work in most cases just fine
if($input == true) $this->multibyte = 4;
else $this->multibyte = 2;
}
function decodePDF() {
// Read the data from pdf file
$infile = @file_get_contents($this->filename, FILE_BINARY);
if (empty($infile))
return "";
// Get all text data.
$transformations = array();
$texts = array();
// Get the list of all objects.
preg_match_all("#obj[\n|\r](.*)endobj[\n|\r]#ismU", $infile . "endobj\r", $objects);
$objects = @$objects[1];
// Select objects with streams.
for ($i = 0; $i < count($objects); $i++) {
$currentObject = $objects[$i];
// Prevent time-out
@set_time_limit ();
if($this->showprogress) {
flush(); ob_flush();
}
// Check if an object includes data stream.
if (preg_match("#stream[\n|\r](.*)endstream[\n|\r]#ismU", $currentObject . "endstream\r", $stream )) {
$stream = ltrim($stream[1]);
// Check object parameters and look for text data.
$options = $this->getObjectOptions($currentObject);
if (!(empty($options["Length1"]) && empty($options["Type"]) && empty($options["Subtype"])) )
continue;
unset($options["Length"]);
// So, we have text data. Decode it.
$data = $this->getDecodedStream($stream, $options);
if (strlen($data)) {
if (preg_match_all("#BT[\n|\r](.*)ET[\n|\r]#ismU", $data . "ET\r", $textContainers)) {
$textContainers = @$textContainers[1];
$this->getDirtyTexts($texts, $textContainers);
} else
$this->getCharTransformations($transformations, $data);
}
}
}
// Analyze text blocks taking into account character transformations and return results.
$this->decodedtext = $this->getTextUsingTransformations($texts, $transformations);
}
function decodeAsciiHex($input) {
$output = "";
$isOdd = true;
$isComment = false;
for($i = 0, $codeHigh = -1; $i < strlen($input) && $input[$i] != '>'; $i++) {
$c = $input[$i];
if($isComment) {
if ($c == '\r' || $c == '\n')
$isComment = false;
continue;
}
switch($c) {
case '\0': case '\t': case '\r': case '\f': case '\n': case ' ': break;
case '%':
$isComment = true;
break;
default:
$code = hexdec($c);
if($code === 0 && $c != '0')
return "";
if($isOdd)
$codeHigh = $code;
else
$output .= chr($codeHigh * 16 + $code);
$isOdd = !$isOdd;
break;
}
}
if($input[$i] != '>')
return "";
if($isOdd)
$output .= chr($codeHigh * 16);
return $output;
}
function decodeAscii85($input) {
$output = "";
$isComment = false;
$ords = array();
for($i = 0, $state = 0; $i < strlen($input) && $input[$i] != '~'; $i++) {
$c = $input[$i];
if($isComment) {
if ($c == '\r' || $c == '\n')
$isComment = false;
continue;
}
if ($c == '\0' || $c == '\t' || $c == '\r' || $c == '\f' || $c == '\n' || $c == ' ')
continue;
if ($c == '%') {
$isComment = true;
continue;
}
if ($c == 'z' && $state === 0) {
$output .= str_repeat(chr(0), 4);
continue;
}
if ($c < '!' || $c > 'u')
return "";
$code = ord($input[$i]) & 0xff;
$ords[$state++] = $code - ord('!');
if ($state == 5) {
$state = 0;
for ($sum = 0, $j = 0; $j < 5; $j++)
$sum = $sum * 85 + $ords[$j];
for ($j = 3; $j >= 0; $j--)
$output .= chr($sum >> ($j * 8));
}
}
if ($state === 1)
return "";
elseif ($state > 1) {
for ($i = 0, $sum = 0; $i < $state; $i++)
$sum += ($ords[$i] + ($i == $state - 1)) * pow(85, 4 - $i);
for ($i = 0; $i < $state - 1; $i++) {
try {
if(false == ($o = chr($sum >> ((3 - $i) * 8)))) {
throw new Exception('Error');
}
$output .= $o;
} catch (Exception $e) { /*Dont do anything*/ }
}
}
return $output;
}
function decodeFlate($data) {
return @gzuncompress($data);
}
function getObjectOptions($object) {
$options = array();
if (preg_match("#<<(.*)>>#ismU", $object, $options)) {
$options = explode("/", $options[1]);
@array_shift($options);
$o = array();
for ($j = 0; $j < @count($options); $j++) {
$options[$j] = preg_replace("#\s+#", " ", trim($options[$j]));
if (strpos($options[$j], " ") !== false) {
$parts = explode(" ", $options[$j]);
$o[$parts[0]] = $parts[1];
} else
$o[$options[$j]] = true;
}
$options = $o;
unset($o);
}
return $options;
}
function getDecodedStream($stream, $options) {
$data = "";
if (empty($options["Filter"]))
$data = $stream;
else {
$length = !empty($options["Length"]) ? $options["Length"] : strlen($stream);
$_stream = substr($stream, 0, $length);
foreach ($options as $key => $value) {
if ($key == "ASCIIHexDecode")
$_stream = $this->decodeAsciiHex($_stream);
elseif ($key == "ASCII85Decode")
$_stream = $this->decodeAscii85($_stream);
elseif ($key == "FlateDecode")
$_stream = $this->decodeFlate($_stream);
elseif ($key == "Crypt") { // TO DO
}
}
$data = $_stream;
}
return $data;
}
function getDirtyTexts(&$texts, $textContainers) {
for ($j = 0; $j < count($textContainers); $j++) {
if (preg_match_all("#\[(.*)\]\s*TJ[\n|\r]#ismU", $textContainers[$j], $parts))
$texts = array_merge($texts, array(@implode('', $parts[1])));
elseif (preg_match_all("#T[d|w|m|f]\s*(\(.*\))\s*Tj[\n|\r]#ismU", $textContainers[$j], $parts))
$texts = array_merge($texts, array(@implode('', $parts[1])));
elseif (preg_match_all("#T[d|w|m|f]\s*(\[.*\])\s*Tj[\n|\r]#ismU", $textContainers[$j], $parts))
$texts = array_merge($texts, array(@implode('', $parts[1])));
}
}
function getCharTransformations(&$transformations, $stream) {
preg_match_all("#([0-9]+)\s+beginbfchar(.*)endbfchar#ismU", $stream, $chars, PREG_SET_ORDER);
preg_match_all("#([0-9]+)\s+beginbfrange(.*)endbfrange#ismU", $stream, $ranges, PREG_SET_ORDER);
for ($j = 0; $j < count($chars); $j++) {
$count = $chars[$j][1];
$current = explode("\n", trim($chars[$j][2]));
for ($k = 0; $k < $count && $k < count($current); $k++) {
if (preg_match("#<([0-9a-f]{2,4})>\s+<([0-9a-f]{4,512})>#is", trim($current[$k]), $map))
$transformations[str_pad($map[1], 4, "0")] = $map[2];
}
}
for ($j = 0; $j < count($ranges); $j++) {
$count = $ranges[$j][1];
$current = explode("\n", trim($ranges[$j][2]));
for ($k = 0; $k < $count && $k < count($current); $k++) {
if (preg_match("#<([0-9a-f]{4})>\s+<([0-9a-f]{4})>\s+<([0-9a-f]{4})>#is", trim($current[$k]), $map)) {
$from = hexdec($map[1]);
$to = hexdec($map[2]);
$_from = hexdec($map[3]);
for ($m = $from, $n = 0; $m <= $to; $m++, $n++)
$transformations[sprintf("%04X", $m)] = sprintf("%04X", $_from + $n);
} elseif (preg_match("#<([0-9a-f]{4})>\s+<([0-9a-f]{4})>\s+\[(.*)\]#ismU", trim($current[$k]), $map)) {
$from = hexdec($map[1]);
$to = hexdec($map[2]);
$parts = preg_split("#\s+#", trim($map[3]));
for ($m = $from, $n = 0; $m <= $to && $n < count($parts); $m++, $n++)
$transformations[sprintf("%04X", $m)] = sprintf("%04X", hexdec($parts[$n]));
}
}
}
}
function getTextUsingTransformations($texts, $transformations) {
$document = "";
for ($i = 0; $i < count($texts); $i++) {
$isHex = false;
$isPlain = false;
$hex = "";
$plain = "";
for ($j = 0; $j < strlen($texts[$i]); $j++) {
$c = $texts[$i][$j];
switch($c) {
case "<":
$hex = "";
$isHex = true;
$isPlain = false;
break;
case ">":
$hexs = str_split($hex, $this->multibyte); // 2 or 4 (UTF8 or ISO)
for ($k = 0; $k < count($hexs); $k++) {
$chex = str_pad($hexs[$k], 4, "0"); // Add tailing zero
if (isset($transformations[$chex]))
$chex = $transformations[$chex];
$document .= html_entity_decode("&#x".$chex.";");
}
$isHex = false;
break;
case "(":
$plain = "";
$isPlain = true;
$isHex = false;
break;
case ")":
$document .= $plain;
$isPlain = false;
break;
case "\\":
$c2 = $texts[$i][$j + 1];
if (in_array($c2, array("\\", "(", ")"))) $plain .= $c2;
elseif ($c2 == "n") $plain .= '\n';
elseif ($c2 == "r") $plain .= '\r';
elseif ($c2 == "t") $plain .= '\t';
elseif ($c2 == "b") $plain .= '\b';
elseif ($c2 == "f") $plain .= '\f';
elseif ($c2 >= '0' && $c2 <= '9') {
$oct = preg_replace("#[^0-9]#", "", substr($texts[$i], $j + 1, 3));
$j += strlen($oct) - 1;
$plain .= html_entity_decode("&#".octdec($oct).";", $this->convertquotes);
}
$j++;
break;
default:
if ($isHex)
$hex .= $c;
elseif ($isPlain)
$plain .= $c;
break;
}
}
$document .= "\n";
//$document .= "<br>";
}
return $document;
}
}