Eclipse-Cannot instantiate the type JsonFactory-CodePudding

I am working in a project, which needs to be logged in with google. Where I use a servlet to authenticate the user. In my servlet , I am getting the error Cannot instantiate the type JsonFactory.

Here is my code:

import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdTokenVerifier;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;

public class IdTokenVerifierAndParser {
private static final String GOOGLE_CLIENT_ID = "_id_";

public static GoogleIdToken.Payload getPayload (String tokenString) throws Exception {

    JsonFactory jacksonFactory = new JsonFactory();
    
    GoogleIdTokenVerifier googleIdTokenVerifier = new GoogleIdTokenVerifier(new NetHttpTransport(), jacksonFactory);

    GoogleIdToken token = GoogleIdToken.parse(jacksonFactory, tokenString);

    if (googleIdTokenVerifier.verify(token)) {
        GoogleIdToken.Payload payload = token.getPayload();
        if (!GOOGLE_CLIENT_ID.equals(payload.getAudience())) {
            throw new IllegalArgumentException("Audience mismatch");
        } else if (!GOOGLE_CLIENT_ID.equals(payload.getAuthorizedParty())) {
            throw new IllegalArgumentException("Client ID mismatch");
        }
        return payload;
    } else {
        throw new IllegalArgumentException("id token cannot be verified");
    }
}
}

CodePudding user response：

JsonFactory is an abstract class. Abstract classes in Java can't be instantiated. You need to instantiate some concrete class that extends it.

Also, by the variable name jacksonFactory I assume you wanted to use the Jackson implementation of this factory. It's marked as deprecated in the documentation, with the recommendation to use GsonFactory implementation instead.

import com.google.api.client.json.gson.GsonFactory;

...

JsonFactory gsonFactory = new GsonFactory();