I have created one poc using Gmail API which read all email and print on console. I have take refrence from Gmail api Java quickstart.
I have follows all the steps like create project, Gmail API enable, OAuth credentials in google cloud console
The problem is, when I run the code all the labels are printed successfully but I'm not able to read mail messages. Some an error are getting which are below:
> Task :GmailQuickstart.main()
Labels:
- CHAT
- SENT
- INBOX
- IMPORTANT
- TRASH
- DRAFT
- SPAM
- CATEGORY_FORUMS
- CATEGORY_UPDATES
- CATEGORY_PERSONAL
- CATEGORY_PROMOTIONS
- CATEGORY_SOCIAL
- STARRED
- UNREAD
Exception in thread "main" com.google.api.client.googleapis.json.GoogleJsonResponseException: 403 Forbidden
GET https://gmail.googleapis.com/gmail/v1/users/me/messages
{
"code": 403,
"details": [
{
"@type": "type.googleapis.com/google.rpc.ErrorInfo",
"reason": "ACCESS_TOKEN_SCOPE_INSUFFICIENT"
}
],
"errors": [
{
"domain": "global",
"message": "Insufficient Permission",
"reason": "insufficientPermissions"
}
],
"message": "Request had insufficient authentication scopes.",
"status": "PERMISSION_DENIED"
}
at com.google.api.client.googleapis.json.GoogleJsonResponseException.from(GoogleJsonResponseException.java:146)
at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:118)
at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:37)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest$1.interceptResponse(AbstractGoogleClientRequest.java:439)
at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1111)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:525)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:466)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:576)
at GmailQuickstart.main(GmailQuickstart.java:80)
> Task :GmailQuickstart.main() FAILED
Execution failed for task ':GmailQuickstart.main()'.
> Process 'command '/home/bhautik/Downloads/jdk-11.0.15.1_linux-x64_bin/data/usr/lib/jvm/jdk-11/bin/java'' finished with non-zero exit value 1
* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
And my code was below:
import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.GmailScopes;
import com.google.api.services.gmail.model.Label;
import com.google.api.services.gmail.model.ListLabelsResponse;
import com.google.api.services.gmail.model.ListMessagesResponse;
import com.google.api.services.gmail.model.Message;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.GeneralSecurityException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/* class to demonstrate use of Gmail list labels API */
public class GmailQuickstart {
private static final String APPLICATION_NAME = "Gmail API Java Quickstart";
private static final JsonFactory JSON_FACTORY = GsonFactory.getDefaultInstance();
private static final String TOKENS_DIRECTORY_PATH = "tokens";
private static final List<String> SCOPES = Collections.singletonList(GmailScopes.GMAIL_LABELS);
private static final String CREDENTIALS_FILE_PATH = "/credentials.json";
private static final String USER_ID = "me";
private static Credential getCredentials(final NetHttpTransport HTTP_TRANSPORT)
throws IOException {
// Load client secrets.
InputStream in = GmailQuickstart.class.getResourceAsStream(CREDENTIALS_FILE_PATH);
if (in == null) {
throw new FileNotFoundException("Resource not found: " + CREDENTIALS_FILE_PATH);
}
GoogleClientSecrets clientSecrets =
GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));
// Build flow and trigger user authorization request.
GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
.setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKENS_DIRECTORY_PATH)))
.setAccessType("offline")
.build();
LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(8888).build();
Credential credential = new AuthorizationCodeInstalledApp(flow, receiver).authorize("user");
//returns an authorized Credential object.
return credential;
}
public static void main(String... args) throws IOException, GeneralSecurityException {
// Build a new authorized API client service.
final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
Gmail service = new Gmail.Builder(HTTP_TRANSPORT, JSON_FACTORY, getCredentials(HTTP_TRANSPORT))
.setApplicationName(APPLICATION_NAME)
.build();
// Print the labels in the user's account.
String user = "me";
ListLabelsResponse listResponse = service.users().labels().list(user).execute();
List<Label> labels = listResponse.getLabels();
if (labels.isEmpty()) {
System.out.println("No labels found.");
} else {
System.out.println("Labels:");
for (Label label : labels) {
System.out.printf("- %s\n", label.getName());
}
}
// Print the message
ListMessagesResponse response = service.users().messages().list(USER_ID).execute();
// List<Message> messages = response.getMessages();
List<Message> messages = new ArrayList<Message>();
while (response.getMessages() != null) {
messages.addAll(response.getMessages());
if (response.getNextPageToken() != null) {
String pageToken = response.getNextPageToken();
response = service.users().messages().list(USER_ID).setPageToken(pageToken).execute();
} else {
break;
}
}
for (Message message : messages) {
System.out.println(message.getId());
System.out.println(message.getPayload());
Message test = service.users().messages().get("me", message.getId()).execute();
System.out.println(test.getSnippet());
}
}
}

