php获取微信openid

1 让用户访问此链接

https://open.weixin.qq.com/connect/oauth2/authorize?appid=你的appid&redirect_uri=回调url&response_type=code&scope=snsapi_base&state=STATE#wechat_redirect

2 在回调函数用get方法获取code

	public function actionGetAccessToken($code){
		if(!isset($_SESSION["openid"])){
			$url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=APPID&secret=SECRET&code=".$code."&grant_type=authorization_code";
//获取授权tooken			
$openid = $this->request_get($url);
			$_SESSION["openid"] = $openid;
		}
		return  $openid;
	}
	function request_get($url)
	{
		// 关闭句柄
		$curl = curl_init(); // 启动一个CURL会话
		curl_setopt($curl, CURLOPT_URL, $url);
		curl_setopt($curl, CURLOPT_HEADER, 0);
		curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
		curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false); // 跳过证书检查
		curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false); // 从证书中检查SSL加密算法是否存在
		$tmpInfo = curl_exec($curl); //返回api的json对象
		if(curl_exec($curl) === false)
		{
		return 'Curl error: ' . curl_error($ch);
		}
		//关闭URL请求
		curl_close($curl);
		return json_decode($tmpInfo)->openid; //返回json对象
	}