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Google PageRank的计算源代码

发布时间:2017-01-04 | 发布者: 东东工作室 | 浏览次数:

  最近对google的PageRank(网页等级)比较感兴趣,一直想知道如何不用google toolbar来获取pr值。苦苦搜索之后,找到如下代码:
  <?php
  /**
  This code is released unto the public domain
  */
  //header("Content-Type: text/plain; charset=utf-8");
  define('GOOGLE_MAGIC', 0xE6359A60);
  //unsigned shift right
  function zeroFill($a, $b)
  {
  $z = hexdec(80000000);
  if ($z & $a)
  {
  $a = ($a>>1);
  $a &= (~$z);
  $a |= 0x40000000;
  $a = ($a>>($b-1));
  }
  else
  {
  $a = ($a>>$b);
  }
  return $a;
  }
  function mix($a,$b,$c) {
  $a -= $b; $a -= $c; $a ^= (zeroFill($c,13));
  $b -= $c; $b -= $a; $b ^= ($a<<8);
  $c -= $a; $c -= $b; $c ^= (zeroFill($b,13));
  $a -= $b; $a -= $c; $a ^= (zeroFill($c,12));
  $b -= $c; $b -= $a; $b ^= ($a<<16);
  $c -= $a; $c -= $b; $c ^= (zeroFill($b,5));
  $a -= $b; $a -= $c; $a ^= (zeroFill($c,3));
  $b -= $c; $b -= $a; $b ^= ($a<<10);
  $c -= $a; $c -= $b; $c ^= (zeroFill($b,15));
  return array($a,$b,$c);
  }
  function GoogleCH($url, $length=null, $init=GOOGLE_MAGIC) {
  if(is_null($length)) {
  $length = sizeof($url);
  }
  $a = $b = 0x9E3779B9;
  $c = $init;
  $k = 0;
  $len = $length;
  while($len >= 12) {
  $a += ($url[$k+0] +($url[$k+1]<<8) +($url[$k+2]<<16) +($url[$k+3]<<24));
  $b += ($url[$k+4] +($url[$k+5]<<8) +($url[$k+6]<<16) +($url[$k+7]<<24));
  $c += ($url[$k+8] +($url[$k+9]<<8) +($url[$k+10]<<16)+($url[$k+11]<<24));
  $mix = mix($a,$b,$c);
  $a = $mix[0]; $b = $mix[1]; $c = $mix[2];
  $k += 12;
  $len -= 12;
  }
  $c += $length;
  switch($len)              /* all the case statements fall through */
  {
  case 11: $c+=($url[$k+10]<<24);
  case 10: $c+=($url[$k+9]<<16);
  case 9 : $c+=($url[$k+8]<<8);
  /* the first byte of c is reserved for the length */
  case 8 : $b+=($url[$k+7]<<24);
  case 7 : $b+=($url[$k+6]<<16);
  case 6 : $b+=($url[$k+5]<<8);
  case 5 : $b+=($url[$k+4]);
  case 4 : $a+=($url[$k+3]<<24);
  case 3 : $a+=($url[$k+2]<<16);
  case 2 : $a+=($url[$k+1]<<8);
  case 1 : $a+=($url[$k+0]);
  /* case 0: nothing left to add */
  }
  $mix = mix($a,$b,$c);
  /*-------------------------------------------- report the result */
  return $mix[2];
  }
  //converts a string into an array of integers containing the numeric value of the char
  function strord($string) {
  for($i=0;$i<strlen($string);$i++) {
  $result[$i] = ord($string{$i});
  }
  return $result;
  }
  // http://www.example.com/ - Checksum: 6540747202
  $url = 'info:'.$_GET['url'];
  $ch = GoogleCH(strord($url));
  $url='info:'.urlencode($_GET['url']);
  echo file_get_contents("http://www.google.com/search?client=navclient-auto&ch=6$ch&ie=UTF-8&oe=UTF-8&features=Rank&q=$url");
  /* use curl send the user angent
  $curl = curl_init("http://www.google.com/search?client=navclient-auto&ch=6$ch&ie=UTF-8&oe=UTF-8&features=Rank&q=$url");
  curl_setopt ($curl, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; GoogleToolbar 2.0.110-big; Windows 2000 5.0)");
  curl_exec($curl);
  */
  ?>
  </></>
    来源:月光博客

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