Implementing Server-Side Authorization - Drive REST API — Google Developers

XDrive RE

Implementing Server-Side Authorization - Drive REST API Google ... https://developers.google.com/drive/web/auth/web-server

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offline

approval_prompt force

offline

CLIENTSECRET_LOCATION client_secret.json

import com.google.api.client.auth.oauth2.Credential;


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import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;

import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeRequestUrl;

import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;

import com.google.api.client.googleapis.auth.oauth2.GoogleTokenResponse;

import com.google.api.client.http.HttpTransport;

import com.google.api.client.http.javanet.NetHttpTransport;

import com.google.api.client.json.jackson2.JacksonFactory;

import com.google.api.services.oauth2.Oauth2;

import com.google.api.services.oauth2.model.Userinfoplus;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.util.Arrays;

import java.util.List;

// ...

class MyClass {

// Path to client_secret.json which should contain a JSON document such as:

// {

// "web": {

// "client_id": "[[YOUR_CLIENT_ID]]",

// "client_secret": "[[YOUR_CLIENT_SECRET]]",

// "auth_uri": "https://accounts.google.com/o/oauth2/auth",

// "token_uri": "https://accounts.google.com/o/oauth2/token"

// }

// }

private static final String CLIENTSECRET_LOCATION = "/client_secret.json";

private static final String APPLICATION_NAME = "Your app name";

private static final String REDIRECT_URI = "urn:ietf:wg:oauth:2.0:oob";

private static final List SCOPES = Arrays.asList(

"https://www.googleapis.com/auth/drive.file",

"email",

"profile");

private static GoogleAuthorizationCodeFlow flow = null;

private static final JacksonFactory JSON_FACTORY =

JacksonFactory.getDefaultInstance();

private static final HttpTransport HTTP_TRANSPORT = new NetHttpTransport();

/**

* Exception thrown when an error occurred while retrieving credentials.

*/

public static class GetCredentialsException extends Exception {

protected String authorizationUrl;

/**

* Construct a GetCredentialsException.

*

* @param authorizationUrl The authorization URL to redirect the user to.

*/

public GetCredentialsException(String authorizationUrl) {

this.authorizationUrl = authorizationUrl;

}


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/**

* Set the authorization URL.

*/

public void setAuthorizationUrl(String authorizationUrl) {

this.authorizationUrl = authorizationUrl;

}

/**

* @return the authorizationUrl

*/

public String getAuthorizationUrl() {

return authorizationUrl;

}

}

/**

* Exception thrown when a code exchange has failed.

*/

public static class CodeExchangeException extends GetCredentialsException {

/**

* Construct a CodeExchangeException.

*


*/

public CodeExchangeException(String authorizationUrl) {

super(authorizationUrl);

}

}

/**

* Exception thrown when no refresh token has been found.

*/

public static class NoRefreshTokenException extends GetCredentialsException {

/**

* Construct a NoRefreshTokenException.

*


*/

public NoRefreshTokenException(String authorizationUrl) {

super(authorizationUrl);

}

}

/**

* Exception thrown when no user ID could be retrieved.

*/

private static class NoUserIdException extends Exception {

}

/**

* Retrieved stored credentials for the provided user ID.

*

* @param userId User's ID.

* @return Stored Credential if found, {@code null} otherwise.

*/

static Credential getStoredCredentials(String userId) {


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// TODO: Implement this method to work with your database. Instantiate a new

// Credential instance with stored accessToken and refreshToken.

throw new UnsupportedOperationException();

}

/**

* Store OAuth 2.0 credentials in the application's database.

*

* @param userId User's ID.

* @param credentials The OAuth 2.0 credentials to store.

*/

static void storeCredentials(String userId, Credential credentials) {

// TODO: Implement this method to work with your database.

// Store the credentials.getAccessToken() and credentials.getRefreshToken()

// string values in your database.


}

/**

* Build an authorization flow and store it as a static class attribute.

*

* @return GoogleAuthorizationCodeFlow instance.

* @throws IOException Unable to load client_secret.json.

*/

static GoogleAuthorizationCodeFlow getFlow() throws IOException {

if (flow == null) {

InputStream in =

MyClass.class.getResourceAsStream(CLIENTSECRET_LOCATION);

GoogleClientSecrets clientSecret =

GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

flow = new GoogleAuthorizationCodeFlow.Builder(

HTTP_TRANSPORT, JSON_FACTORY, clientSecret, SCOPES)

.setAccessType("offline")

.setApprovalPrompt("force")

.build();

}

return flow;

}

/**

* Exchange an authorization code for OAuth 2.0 credentials.

*

* @param authorizationCode Authorization code to exchange for OAuth 2.0

* credentials.

* @return OAuth 2.0 credentials.

* @throws CodeExchangeException An error occurred.

*/

static Credential exchangeCode(String authorizationCode)

throws CodeExchangeException {

try {

GoogleAuthorizationCodeFlow flow = getFlow();

GoogleTokenResponse response = flow

.newTokenRequest(authorizationCode)

.setRedirectUri(REDIRECT_URI)

.execute();

return flow.createAndStoreCredential(response, null);

} catch (IOException e) {


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System.err.println("An error occurred: " + e);

throw new CodeExchangeException(null);

}

}

/**

* Send a request to the UserInfo API to retrieve the user's information.

*

* @param credentials OAuth 2.0 credentials to authorize the request.

* @return User's information.

* @throws NoUserIdException An error occurred.

*/

static Userinfoplus getUserInfo(Credential credentials)

throws NoUserIdException {

Oauth2 userInfoService = new Oauth2.Builder(

HTTP_TRANSPORT, JSON_FACTORY, credentials)

.setApplicationName(APPLICATION_NAME)

.build();

Userinfoplus userInfo = null;

try {

userInfo = userInfoService.userinfo().get().execute();


System.err.println("An error occurred: " + e);

}

if (userInfo != null && userInfo.getId() != null) {

return userInfo;

} else {

throw new NoUserIdException();

}

}

/**

* Retrieve the authorization URL.

*

* @param emailAddress User's e-mail address.

* @param state State for the authorization URL.

* @return Authorization URL to redirect the user to.


*/

public static String getAuthorizationUrl(String emailAddress, String state)

throws IOException {

GoogleAuthorizationCodeRequestUrl urlBuilder = getFlow()

.newAuthorizationUrl()

.setRedirectUri(REDIRECT_URI)

.setState(state);

urlBuilder.set("user_id", emailAddress);

return urlBuilder.build();

}

/**

* Retrieve credentials using the provided authorization code.

*

* This function exchanges the authorization code for an access token and

* queries the UserInfo API to retrieve the user's e-mail address. If a

* refresh token has been retrieved along with an access token, it is stored

* in the application database using the user's e-mail address as key. If no

* refresh token has been retrieved, the function checks in the application


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* database for one and returns it if found or throws a NoRefreshTokenException

* with the authorization URL to redirect the user to.

*

* @param authorizationCode Authorization code to use to retrieve an access

* token.

* @param state State to set to the authorization URL in case of error.

* @return OAuth 2.0 credentials instance containing an access and refresh

* token.

* @throws NoRefreshTokenException No refresh token could be retrieved from

* the available sources.


*/

public static Credential getCredentials(String authorizationCode, String state)

throws CodeExchangeException, NoRefreshTokenException, IOException {

String emailAddress = "";

try {

Credential credentials = exchangeCode(authorizationCode);

Userinfoplus userInfo = getUserInfo(credentials);

String userId = userInfo.getId();

emailAddress = userInfo.getEmail();

if (credentials.getRefreshToken() != null) {

storeCredentials(userId, credentials);

return credentials;

} else {

credentials = getStoredCredentials(userId);

if (credentials != null && credentials.getRefreshToken() != null) {

return credentials;

}

}

} catch (CodeExchangeException e) {

e.printStackTrace();

// Drive apps should try to retrieve the user and credentials for the

// current session.

// If none is available, redirect the user to the authorization URL.

e.setAuthorizationUrl(getAuthorizationUrl(emailAddress, state));

throw e;

} catch (NoUserIdException e) {

e.printStackTrace();

}

// No refresh token has been retrieved.

String authorizationUrl = getAuthorizationUrl(emailAddress, state);

throw new NoRefreshTokenException(authorizationUrl);

}

}


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File

import com.google.api.client.auth.oauth2.Credential;

import com.google.api.client.http.HttpTransport;

import com.google.api.client.http.javanet.NetHttpTransport;

import com.google.api.client.json.jackson2.JacksonFactory;

import com.google.api.services.drive.Drive;

// ...

public class MyClass {

private static final String APPLICATION_NAME = "Your app name";

private static final JacksonFactory JSON_FACTORY =

JacksonFactory.getDefaultInstance();

private static final HttpTransport HTTP_TRANSPORT =

new NetHttpTransport();

// ...

/**

* Build a Drive service object.

*

* @param credentials OAuth 2.0 credentials.

* @return Drive service object.

*/

static Drive buildService(Credential credentials) {

return new Drive.Builder(HTTP_TRANSPORT, JSON_FACTORY, credentials)

.setApplicationName(APPLICATION_NAME)

.build();

}

// ...

}


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GET

File

401

import com.google.api.client.http.HttpResponse;

import com.google.api.client.http.HttpResponseException;

import com.google.api.services.drive.Drive;

import com.google.api.services.drive.model.File;

import java.io.IOException;

// ...

public class MyClass {

// ...

/**

* Print a file's metadata.

*

* @param service Drive API service instance.

* @param fileId ID of the file to print metadata for.

*/

static void printFile(Drive service, String fileId) {

try {

File file = service.files().get(fileId).execute();

System.out.println("Title: " + file.getTitle());

System.out.println("Description: " + file.getDescription());

System.out.println("MIME type: " + file.getMimeType());

} catch (HttpResponseException e) {

if (e.getStatusCode() == 401) {

// Credentials have been revoked.

// TODO: Redirect the user to the authorization URL.


}


System.out.println("An error occurred: " + e);

}

}

// ...

}


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Documents

Implementing Server-Side Authorization - Drive REST API — Google Developers