Page Summary
-
All requests to Google Pay's Omnichannel API must be authorized using OAuth 2.0 with a service account.
-
The provided Java code demonstrates how to authorize requests using a service account key file and make API calls.
-
To use the code, you need to add specific Maven dependencies for Google API Client, HTTP Client, and Gson libraries.
-
Further information on OAuth 2.0 and Google API client libraries is available through provided links.
All requests to Google Pay APIs must be authorized by an authenticated user. Your application must include the following code to authorize the Omnichannel API.
import
com.google.api.client.googleapis.auth.oauth2.GoogleCredential
;
import
com.google.api.client.googleapis.javanet.GoogleNetHttpTransport
;
import
com.google.api.client.http.FileContent
;
import
com.google.api.client.http.GenericUrl
;
import
com.google.api.client.http.HttpContent
;
import
com.google.api.client.http.HttpRequest
;
import
com.google.api.client.http.HttpRequestFactory
;
import
com.google.api.client.http.HttpResponse
;
import
com.google.api.client.http.HttpTransport
;
import
com.google.api.client.json.jackson2.JacksonFactory
;
import
com.google.common.io.CharStreams
;
import
com.google.gson.JsonObject
;
import
com.google.gson.JsonParser
;
import
java.io.File
;
import
java.io.FileInputStream
;
import
java.io.FileNotFoundException
;
import
java.io.IOException
;
import
java.io.InputStream
;
import
java.io.InputStreamReader
;
import
java.nio.charset.Charset
;
import
java.security.GeneralSecurityException
;
import
java.util.Collections
;
public
class
OauthClient
{
private
static
final
String
JWT_PATH
=
"service-account-key.json"
;
private
static
final
String
API_SCOPE
=
"https://www.googleapis.com/auth/nbupaymentsmerchants"
;
private
static
final
String
POST_JSON
=
"initiate.json"
;
private
static
final
String
API_URL
=
"https://nbupayments.googleapis.com/v1/merchantPayments:initiate"
;
public
static
final
Charset
UTF8
=
Charset
.
forName
(
"UTF-8"
);
public
static
final
int
HTTP_TIMEOUT_MS
=
10000
;
public
static
void
main
(
String
args
[])
{
HttpTransport
httpTransport
;
HttpRequestFactory
httpRequestFactory
;
try
{
httpTransport
=
GoogleNetHttpTransport
.
newTrustedTransport
();
GoogleCredential
credential
=
getGoogleCredential
(
httpTransport
);
httpRequestFactory
=
httpTransport
.
createRequestFactory
(
credential
);
doPostApplication
(
httpRequestFactory
);
}
catch
(
IOException
|
GeneralSecurityException
e
)
{
System
.
out
.
println
(
"Error in posting data."
);
}
}
/**
Creates
a
{
@link
HttpContent
}
from
the
json
file
.
*/
private
static
HttpContent
getContent
()
{
return
new
FileContent
(
"application/json"
,
new
File
(
POST_JSON
));
}
/**
Creates
a
new
credential
using
the
service
account
json
file
and
Oauth
scope
.
*/
private
static
GoogleCredential
getGoogleCredential
(
HttpTransport
httpTransport
)
throws
FileNotFoundException
,
IOException
{
return
GoogleCredential
.
fromStream
(
new
FileInputStream
(
new
File
(
JWT_PATH
)),
httpTransport
,
JacksonFactory
.
getDefaultInstance
())
.
createScoped
(
Collections
.
singleton
(
API_SCOPE
));
}
/**
Gets
the
specification
of
an
application
from
the
Google
servers
.
*/
private
static
void
doPostApplication
(
HttpRequestFactory
requestFactory
)
throws
IOException
{
GenericUrl
url
=
new
GenericUrl
(
API_URL
);
HttpRequest
httpRequest
=
requestFactory
.
buildPostRequest
(
url
,
getContent
());
doHttpRequest
(
httpRequest
);
}
/**
Executes
HTTP
request
against
the
API
and
prints
response
.
*/
private
static
void
doHttpRequest
(
HttpRequest
httpRequest
)
throws
IOException
{
//
Set
read
timeout
.
httpRequest
.
setReadTimeout
(
HTTP_TIMEOUT_MS
)
.
setThrowExceptionOnExecuteError
(
false
);
HttpResponse
httpResponse
=
httpRequest
.
execute
();
System
.
out
.
println
(
"Status code: "
+
httpResponse
.
getStatusCode
());
String
responseContent
=
inputStreamToString
(
httpResponse
.
getContent
());
//
Parse
and
print
formatted
response
.
JsonObject
response
=
new
JsonParser
()
.
parse
(
responseContent
)
.
getAsJsonObject
();
System
.
out
.
println
(
"response: "
+
response
);
}
/**
Reads
input
stream
contents
using
the
UTF
-
8
charset
into
a
string
.
*/
private
static
String
inputStreamToString
(
InputStream
in
)
throws
IOException
{
return
CharStreams
.
toString
(
new
InputStreamReader
(
in
,
UTF8
));
}
}
Maven dependencies
To make your code work, you must add the following Maven dependencies while building the app.
<dependencies>
<dependency>
<groupId>com.google.api-client</groupId>
<artifactId>google-api-client</artifactId>
<version>1.22.0</version>
</dependency>
<dependency>
<groupId>com.google.http-client</groupId>
<artifactId>google-http-client</artifactId>
<version>1.22.0</version>
</dependency>
<dependency>
<groupId>com.google.http-client</groupId>
<artifactId>google-http-client-jackson</artifactId>
<version>1.22.0</version>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.0</version>
</dependency>
</dependencies>
Oauth 2.0 References
-
https://developers.google.com/identity/protocols/OAuth2#serviceaccount
-
https://developers.google.com/identity/protocols/OAuth2ServiceAccount
The following client libraries integrate with popular frameworks, which makes implementing OAuth 2.0 simpler.
- Google-api-client
- Google-http-java-client
