alipay.system.oauth.token (Obtain the access token)

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("Call succeeds");
} else {
System.out.println("Call fails");
}

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 = 'Please fill in the developer's private key in a line of string, moving the head, tail, and carriage return';
$aop->alipayrsaPublicKey='Please fill in Alipay public key in a line of string';
$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);

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"

  //To ensure a secure communication, verify whether the sign value in the response sample is provided by Ant finance.

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

<alipay_system_oauth_token_response>
<code>10000</code>
<msg>Success</msg>  <alipay_user_id>Obsolete. Do not use it.</alipay_user_id>
  <user_id>2088102150477652</user_id>
  <access_token>20120823ac6ffaa4d2d84e7384bf983531473993</access_token>
  <expires_in>3600</expires_in>
  <refresh_token>20120823ac6ffdsdf2d84e7384bf983531473993</refresh_token>
  <re_expires_in>3600</re_expires_in>
  <auth_token_type>permanent</auth_token_type>
</alipay_system_oauth_token_response>

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