android - 无法实例化类型 JsonFactory

Question

我正在尝试使用 GoogleAuthUtil 验证我从 Google 收到的 JWT。我正在尝试使用 this page 底部的代码.这是我的确切源代码:

import java.io.IOException;
import java.security.GeneralSecurityException;
import java.util.Arrays;
import java.util.List;

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 Checker {

    private final List mClientIDs;
    private final String mAudience;
    private final GoogleIdTokenVerifier mVerifier;
    private final JsonFactory mJFactory;
    private String mProblem = "Verification failed. (Time-out?)";

    public Checker(String[] clientIDs, String audience) {
        mClientIDs = Arrays.asList(clientIDs);
        mAudience = audience;
        NetHttpTransport transport = new NetHttpTransport();
        mJFactory = new JsonFactory();
        mVerifier = new GoogleIdTokenVerifier(transport, mJFactory);
    }

    public GoogleIdToken.Payload check(String tokenString) {
        GoogleIdToken.Payload payload = null;
        try {
            GoogleIdToken token = GoogleIdToken.parse(mJFactory, tokenString);
            if (mVerifier.verify(token)) {
                GoogleIdToken.Payload tempPayload = token.getPayload();
                if (!tempPayload.getAudience().equals(mAudience))
                    mProblem = "Audience mismatch";
                else if (!mClientIDs.contains(tempPayload.getIssuee()))
                    mProblem = "Client ID mismatch";
                else
                    payload = tempPayload;
            }
        } catch (GeneralSecurityException e) {
            mProblem = "Security issue: " + e.getLocalizedMessage();
        } catch (IOException e) {
            mProblem = "Network problem: " + e.getLocalizedMessage();
        }
        return payload;
    }

    public String problem() {
        return mProblem;
    }
}

我遇到的问题是在这一行:mJFactory = new JsonFactory();，我收到错误 Cannot instantiate the type JsonFactory。我很确定我正在正确调用构造函数并且我已正确导入所有库，所以我不知道为什么会出现此错误。如果有人可以帮助我，那就太好了!如果有任何其他有用的信息，请告诉我。

编辑:这是 the Javadoc 的链接

Answer 1

好的，问题是我在复制代码时犯了一个小错误。 JsonFactory是一个抽象类，所以需要使用子类GsonFactory来提供实现。