CI框架实现控制器作为域名或者二级域名访问

Codeigniter的URI还没那么强大，要实现将二级域名绑定到某个控制器上，还得动点手脚。要实现的结果是将
http://www.z1988.com/admin => http://admin.z1988.com
http://www.z1988.com/member => http://m.z1988.com
来访问。 首先你要确保域名泛解析了。泛域名解析是存在一定危害的，所以你要：

在application/config/下建立一个domain.php文件，这里面放你要解析的子域名（对应CI控制器）

$domain = array(
    'admin.z1988.com'=>'admin',
    'm.z1988.com'=>'member',
);

然后修改system/core/URI.php的_set_uri_string方法：
如果配置中二级域名或域名不存在就404错误吧，这样就避免了泛解析的危害。

	protected function _set_uri_string($str)
	{
		// Filter out control characters and trim slashes
		$this->uri_string = trim(remove_invisible_characters($str, FALSE), '/');
		//绑定域名访问url
		include(APPPATH.'config/domain.php');
		$server_name = $_SERVER['SERVER_NAME'];
		if (isset($domain[$server_name])) {
			if( $domain[$server_name] != ''  ){
				$this->uri_string = '' . $domain[ $server_name ] .'/'. $this->uri_string;
			}
		}else{
			show_404();
		}

		if ($this->uri_string !== '')
		{
			// Remove the URL suffix, if present
			if (($suffix = (string) $this->config->item('url_suffix')) !== '')
			{
				$slen = strlen($suffix);

				if (substr($this->uri_string, -$slen) === $suffix)
				{
					$this->uri_string = substr($this->uri_string, 0, -$slen);
				}
			}

			$this->segments[0] = NULL;
			// Populate the segments array
			foreach (explode('/', trim($this->uri_string, '/')) as $val)
			{
				$val = trim($val);
				// Filter segments for security
				$this->filter_uri($val);

				if ($val !== '')
				{
					$this->segments[] = $val;
				}
			}

			unset($this->segments[0]);
		}
	}