paypal 授权登录实现

_sanbox_flag = $flag;
        $this->_redirect_uri = $redirect_uri;
        $this->_client_id = $client_id;
        $this->_client_secret = $client_secret;
        $this->_scope = $scope;
        $this->_state = $state;
    }

	/**
     * 创建paypal request url
     * @return string
     */
    public function create_request_url()
    {
        $oauth2_auth_uri = $this->_sanbox_flag ? $this->_sanbox_oauth2_auth_uri :$this->_live_oauth2_auth_uri;
        $url =  $oauth2_auth_uri.'?'.
        http_build_query(
            array(
                'client_id' => $this->_client_id, //通过应用程序注册流程获得的唯一客户端标识符。必需。
                'response_type' =>'code', //表明授权代码被发送回应用程序返回URL。为了使访问令牌在用户代理中不可见， 建议使用code一值。如果您希望在响应中同时收到授权代码和 id_token ，请传递 code+id_token。另一个可能的 response_type 值是 token ——大部分由javascript和移动客户端等公共客户端使用。
                'scope' => $this->_scope,//;implode(',', $this->scope),
                'redirect_uri' => urlencode($this->_redirect_uri), //应用程序的返回URL。结构、主机名和端口必须与您在注册应用程序时设置的返回URL相符。
                'nonce' => time().rand(), //不透明的随机标识符，可减少重放攻击风险。简单的函数是：(timestamp + Base64 encoding (random\[16\]))。
                'state' => $this->_state, // CSRF验证码
            )
        );
        return $url;
    }

    /**
	 * get PayPal access token
	 * @param  string $code ?
	 * @return string       access token
	 */
	public function acquire_access_token($code ) {
		$accessToken = null;

		try {
			$postvals = sprintf("client_id=%s&client_secret=%s&grant_type=authorization_code&code=%s",$this->_client_id,$this->_client_secret,$code);
			if($this->_sanbox_flag)
			   $ch = curl_init($this->_token_service_sandbox_url);
		    else
		       $ch = curl_init($this->_token_service_live_url);	

			$options = array(
				CURLOPT_POST           => 1,
				CURLOPT_VERBOSE        => 1,
				CURLOPT_POSTFIELDS     => $postvals,
				CURLOPT_RETURNTRANSFER => 1,
				CURLOPT_SSL_VERIFYPEER => FALSE,
				//CURLOPT_SSLVERSION => 2
			);

			curl_setopt_array($ch, $options);
			$response = curl_exec($ch);
			$error = curl_error($ch);

			curl_close( $ch );

			if (!$response ) {
				throw new Exception( "Error retrieving access token: " . curl_error($ch));
			}
			$jsonResponse = json_decode($response );

			if ( isset( $jsonResponse->access_token) ) {
				$accessToken = $jsonResponse->access_token;
			}

		} catch( Exception $e) {
			throw new Exception($e->getMessage(), 1);
		}

		return $accessToken;
	}

    /**
     * get the PayPal user profile, decoded
     * @param  string $accessToken
     * @return object
     */
    public function acquire_paypal_user_profile($accessToken ) {
        try {
            if($this->_sanbox_flag)
               $url = $this->_acquire_user_profile_sandbox_url . $accessToken;
            else
                $url = $this->_acquire_user_profile_live_url . $accessToken;    

            $ch = curl_init( $url );
            $options = array(
                CURLOPT_RETURNTRANSFER => 1,
                CURLOPT_SSL_VERIFYPEER => FALSE,
                //CURLOPT_SSLVERSION => 2
            );
            curl_setopt_array($ch, $options);

            $response = curl_exec($ch);
            $error = curl_error( $ch);
            curl_close( $ch );

            if (!$response ) 
            {
                return false;
            }
            return json_decode($response);
        } catch( Exception $e ) {
            return false;
        }
    }

   

    

}
?>