本文实例讲述了PHP实现的一致性HASH算法。分享给大家供大家参考，具体如下：

<?php// +----------------------------------------------------------------------// | Perfect Is Shit// +----------------------------------------------------------------------// | PHP实现：一致性HASH算法// +----------------------------------------------------------------------// | Author: alexander <gt199899@gmail.com>// +----------------------------------------------------------------------// | Datetime: 2017-01-11 16:01:36// +----------------------------------------------------------------------// | Copyright: Perfect Is Shit// +----------------------------------------------------------------------class ConsistentHashing{  // 圆环  // hash -> 节点  private $_ring = array();  // 所有节点  // 节点 -> hash  public $nodes = array();  // 每个节点的虚拟节点  public $virtual = 64;  /**   * 构造   * @param array $nodes 初始化的节点列表   */  public function __construct($nodes = array())  {    if (!empty($nodes)) {      foreach ($nodes as $value) {        $this->addNode($value);      }    }  }  /**   * 获取圆环内容   * @return array $this->_ring   */  public function getRing()  {    return $this->_ring;  }  /**   * time33 函数   * @param string $str   * @return 32位正整数   * @author 大神们   */  public function time33($str)  {    // hash(i) = hash(i-1) * 33 + str[i]    // $hash = 5381; ## 将hash设置为0，竟然比设置为5381分布效果更好！！！    $hash = 0;    $s  = md5($str); //相比其它版本，进行了md5加密    $seed = 5;    $len = 32;//加密后长度32    for ($i = 0; $i < $len; $i++) {      // (hash << 5) + hash 相当于 hash * 33      //$hash = sprintf("%u", $hash * 33) + ord($s{$i});      //$hash = ($hash * 33 + ord($s{$i})) & 0x7FFFFFFF;      $hash = ($hash << $seed) + $hash + ord($s{$i});    }    return $hash & 0x7FFFFFFF;  }  /**   * 增加节点   * @param string $node 节点名称   * @return object $this   */  public function addNode($node)  {    if (in_array($node, array_keys($this->nodes))) {      return;    }    for ($i = 1; $i <= $this->virtual; $i++) {      $key         = $this->time33($node . "-" . $i);      $this->_ring[$key]  = $node;      $this->nodes[$node][] = $key;    }    ksort($this->_ring, SORT_NUMERIC);    return $this;  }  /**   * 获取字符串的HASH在圆环上面映射到的节点   * @param string $key   * @return string $node   */  public function getNode($key)  {    $node = current($this->_ring);    $hash = $this->time33($key);    foreach ($this->_ring as $key => $value) {      if ($hash <= $key) {        $node = $value;        break;      }    }    return $node;  }  /**   * 获取映射到特定节点的KEY   * 此方法需手动调用，非特殊情况不建议程序中使用此方法   * @param string $node   * @param string $keyPre   * @return mixed   */  public function getKey($node, $keyPre = ""){    if(!in_array($node, array_keys($this->nodes))){      return false;    }    $result = false;    for($i=1;$i<=10000;$i++){      $key = $keyPre . md5(rand(1000, 9999));      if($this->getNode($key) == $node){        $result = true;        break;      }    }    return $result ? $key : false;  }}$ch_obj = new ConsistentHashing();$ch_obj->addNode("node_1");$ch_obj->addNode("node_2");$ch_obj->addNode("node_3");$ch_obj->addNode("node_4");$ch_obj->addNode("node_5");$ch_obj->addNode("node_6");// +----------------------------------------------------------------------// | 查看key映射到的节点// +----------------------------------------------------------------------$key1 = "asofiwjamfdalksjfkasasdflasfja";$key2 = "jaksldfjlasfjsdjfioafaslkjflsadkjfl";$key3 = "asjldflkjasfsdjflkajkldsjfksajdlflajs";$key4 = "iowanfasijfmasdnfoas";$key5 = "pqkisndfhoalnfiewlkl";$key6 = "qjklasjdifoajfalsjflsa";echo sprintf("%-50s 映射到节点 %s", $key1, $ch_obj->getNode($key1));echo sprintf("%-50s 映射到节点 %s", $key2, $ch_obj->getNode($key2));echo sprintf("%-50s 映射到节点 %s", $key3, $ch_obj->getNode($key3));echo sprintf("%-50s 映射到节点 %s", $key4, $ch_obj->getNode($key4));echo sprintf("%-50s 映射到节点 %s", $key5, $ch_obj->getNode($key5));echo sprintf("%-50s 映射到节点 %s", $key6, $ch_obj->getNode($key6));// +----------------------------------------------------------------------// | 查看圆环和节点信息// +----------------------------------------------------------------------// var_dump($ch_obj->getRing());// var_dump($ch_obj->nodes);// +----------------------------------------------------------------------// | 获取特定节点的KEY// +----------------------------------------------------------------------// $key1 = $ch_obj->getKey("node_1", "pre_");// var_dump($key1);// +----------------------------------------------------------------------// | 测试分布// +----------------------------------------------------------------------// $keys = array();// $rings = array();// for ($i = 1; $i <= 60000; $i++) {//   $key = sha1(rand(1000000,9999999));//   $node = $ch_obj->getNode($key);//   $rings[$node] = isset($rings[$node]) ? ++$rings[$node] : 1;// }// var_dump($rings);

运行结果：

asofiwjamfdalksjfkasasdflasfja           映射到节点 node_1jaksldfjlasfjsdjfioafaslkjflsadkjfl        映射到节点 node_2asjldflkjasfsdjflkajkldsjfksajdlflajs       映射到节点 node_1iowanfasijfmasdnfoas                映射到节点 node_2pqkisndfhoalnfiewlkl                映射到节点 node_3qjklasjdifoajfalsjflsa               映射到节点 node_5

PS：这里再为大家提供2款hash相关在线工具供大家参考使用：

在线散列/哈希算法加密工具：http://tools.jb51.net/password/hash_encrypt

在线MD5/hash/SHA-1/SHA-2/SHA-256/SHA-512/SHA-3/RIPEMD-160加密工具：http://tools.jb51.net/password/hash_md5_sha

更多关于PHP相关内容感兴趣的读者可查看本站专题：《php加密方法总结》、《PHP编码与转码操作技巧汇总》、《PHP数学运算技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》、《PHP数据结构与算法教程》、《php程序设计算法总结》及《php正则表达式用法总结》

希望本文所述对大家PHP程序设计有所帮助。