AlipayClient alipayClient = new DefaultAlipayClient("https://openapi.alipay.com/gateway.do","app_id","your private_key","json","GBK","alipay_public_key","RSA2");
AlipaySystemOauthTokenRequest request = new AlipaySystemOauthTokenRequest();
request.setGrantType("authorization_code");
request.setCode("4b203fe6c11548bcabd8da5bb087a83b");
request.setRefreshToken("201208134b203fe6c11548bcabd8da5bb087a83b");
AlipaySystemOauthTokenResponse response = alipayClient.execute(request);
if(response.isSuccess()){
System.out.println("调用成功");
} else {
System.out.println("调用失败");
}

IAopClient client = new DefaultAopClient("https://openapi.alipay.com/gateway.do", "app_id", "merchant_private_key", "json", "1.0", "RSA2", "alipay_public_key", "GBK", false);
AlipaySystemOauthTokenRequest  request= new AlipaySystemOauthTokenRequest() ;
request.GrantType = "authorization_code";
request.Code = "4b203fe6c11548bcabd8da5bb087a83b";
request.RefreshToken = "201208134b203fe6c11548bcabd8da5bb087a83b";
AlipaySystemOauthTokenResponse response=client.execute(request);
Console.WriteLine(response.Body);

$aop = new AopClient ();
$aop->gatewayUrl = 'https://openapi.alipay.com/gateway.do';
$aop->appId = 'your app_id';
$aop->rsaPrivateKey = '请填写开发者私钥去头去尾去回车，一行字符串';
$aop->alipayrsaPublicKey='请填写支付宝公钥，一行字符串';
$aop->apiVersion = '1.0';
$aop->signType = 'RSA2';
$aop->postCharset='GBK';
$aop->format='json';
$request = new AlipaySystemOauthTokenRequest ();
$request->setGrantType("authorization_code");
$request->setCode("4b203fe6c11548bcabd8da5bb087a83b");
$request->setRefreshToken("201208134b203fe6c11548bcabd8da5bb087a83b");
$result = $aop->execute ( $request); 

$responseNode = str_replace(".", "_", $request->getApiMethodName()) . "_response";
$resultCode = $result->$responseNode->code;
if(!empty($resultCode)&&$resultCode == 10000){
echo "成功";
} else {
echo "失败";
}

https://openapi.alipay.com/gateway.do?timestamp=2013-01-01 08:08:08&method=alipay.system.oauth.token&app_id=4472&sign_type=RSA2&sign=ERITJKEIJKJHKKKKKKKHJEREEEEEEEEEEE&version=1.0&grant_type=
  "authorization_code"
&code=
  "4b203fe6c11548bcabd8da5bb087a83b"
&refresh_token=
  "201208134b203fe6c11548bcabd8da5bb087a83b"

//为确保安全通信，需自行验证响应示例中的sign值是否为蚂蚁金服所提供。

{
	"alipay_system_oauth_token_response":{
		"access_token":"20120823ac6ffaa4d2d84e7384bf983531473993",
		"refresh_token":"20120823ac6ffdsdf2d84e7384bf983531473993",
		"user_id":"2088102150477652",
		"re_expires_in":"3600",
		"expires_in":"3600"
	}
}

{
	"alipay_system_oauth_token_response":{
		"msg":"Service Currently Unavailable",
		"code":"20000",
		"sub_msg":"系统繁忙",
		"sub_code":"isp.unknow-error"
	},
	"sign":"ERITJKEIJKJHKKKKKKKHJEREEEEEEEEEEE"
}