使用Java应用程序中的Google Drive API

Question

我在使用Java将本地文件从硬盘驱动器写入Google云端硬盘时遇到问题。最终目标是将应用程序放在GAE上并直接写入Google云端硬盘。根据Drive API的文献，我有以下结构：

package com.d2d.googledrive;

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

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.HttpTransport;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.File;
import com.google.api.services.drive.model.ParentReference;


public class GDFileInsert {

private static HttpTransport    httpTransport;
private static String           APPLICATION_NAME        = "my_app_name";
private static String           USER_EMAIL_ADDRESS      = "username@gmail.com";
private static JacksonFactory   JSON_FACTORY            =  JacksonFactory.getDefaultInstance();
private static String           SERVICE_ACCOUNT_EMAIL   =  "account-1@my_app_name.iam.gserviceaccount.com";


public  static void main(String[] args) throws IOException, GeneralSecurityException {

    httpTransport = GoogleNetHttpTransport.newTrustedTransport();   

    GoogleCredential credential = new GoogleCredential.Builder()
          .setTransport(httpTransport)
          .setJsonFactory(JSON_FACTORY)
          .setServiceAccountId(SERVICE_ACCOUNT_EMAIL)
          .setServiceAccountUser(USER_EMAIL_ADDRESS)
          .setServiceAccountScopes(DriveScopes.all())
          .setServiceAccountPrivateKeyFromP12File(
                  new java.io.File("Resources/d2dloads-8d4579d34d46.p12"))
          .build();

      Drive service = new Drive.Builder(httpTransport, JSON_FACTORY, null)
          .setHttpRequestInitializer(credential).setApplicationName(APPLICATION_NAME).build();



    // File's metadata.
    File body = new File();
    body.setTitle("My File Title");
    body.setDescription("My File Description");
    body.setMimeType("text/plain");

    String parentId = "ParentDir";

    // Set the parent folder.
    if (parentId != null && parentId.length() > 0) {
      body.setParents(
          Arrays.asList(new ParentReference().setId(parentId)));
    }

    String filename = "Resources/myfile.txt";

    // File's content.
    java.io.File fileContent = new java.io.File(filename);
    FileContent mediaContent = new FileContent("text/plain", fileContent);
    try {
      File file = service.files().insert(body, mediaContent).execute();

      // Uncomment the following line to print the File ID.
      System.out.println("Inserted File ID: " + file.getId());

    } catch (IOException e) {

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

    }
}


}

当我运行程序时，它给出了如下错误：

Exception in thread "main" java.lang.NoClassDefFoundError: com/google/api/services/drive/DriveScopes
at com.d2d.googledrive.GDFileInsert.main(GDFileInsert.java:36)

基本上是＆＃34; .setServiceAccountScopes（DriveScopes.all（））＆＃34;。我尝试过将API_KEY用于其他选项的各种选项，但没有成功。我确实为我的项目激活了Google Drive API，还创建了服务帐户密钥，API密钥和OAuth2密钥。

我不确定我做错了什么。任何指导都会有所帮助我还附上了WEB-INF / Lib jars图片

..

编辑2：

@ Konqi的建议适用于上述问题。现在还有另一个错误NullPointerException @＆＃34; File file = service.files（）。insert（body，mediaContent）.execute（）＆＃34;。我已经定义了需要上传的文件。任何指导或建议。

Exception in thread "main" java.lang.NullPointerException
at com.google.api.client.repackaged.com.google.common.base.Preconditions.checkNotNull(Preconditions.java:191)
at com.google.api.client.util.Preconditions.checkNotNull(Preconditions.java:127)
at com.google.api.client.json.jackson2.JacksonFactory.createJsonParser(JacksonFactory.java:96)
at com.google.api.client.json.JsonObjectParser.parseAndClose(JsonObjectParser.java:85)
at com.google.api.client.json.JsonObjectParser.parseAndClose(JsonObjectParser.java:81)
at com.google.api.client.auth.oauth2.TokenResponseException.from(TokenResponseException.java:88)
at com.google.api.client.auth.oauth2.TokenRequest.executeUnparsed(TokenRequest.java:287)
at com.google.api.client.auth.oauth2.TokenRequest.execute(TokenRequest.java:307)
at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.executeRefreshToken(GoogleCredential.java:268)
at com.google.api.client.auth.oauth2.Credential.refreshToken(Credential.java:489)
at com.google.api.client.auth.oauth2.Credential.intercept(Credential.java:217)
at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:859)
at com.google.api.client.googleapis.media.MediaHttpUploader.executeCurrentRequestWithoutGZip(MediaHttpUploader.java:545)
at com.google.api.client.googleapis.media.MediaHttpUploader.executeCurrentRequest(MediaHttpUploader.java:562)
at com.google.api.client.googleapis.media.MediaHttpUploader.executeUploadInitiation(MediaHttpUploader.java:519)
at com.google.api.client.googleapis.media.MediaHttpUploader.resumableUpload(MediaHttpUploader.java:384)
at com.google.api.client.googleapis.media.MediaHttpUploader.upload(MediaHttpUploader.java:336)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:418)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:343)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:460)
at com.d2d.googledrive.GDFileInsert.main(GDFileInsert.java:69)