在我的应用中访问Google云端硬盘数据

Question

我需要在我的应用上访问一个共享文件夹，这是在google驱动器“drive.google.com”上创建的共享文件夹。这将包括我的应用程序上的所有子文件和文件夹。我试图使用谷歌驱动器api来访问数据，但它没有显示我在驱动器上的任何数据。  我使用了this链接来访问该文件夹。

请帮我解决这个问题。请提供有效的参考链接。

Answer 1

虽然没有明确记录，但可以将Android应用程序连接到公共云端硬盘文件夹。

先决条件

1. 在适用于您应用的开发者控制台中设置项目
2. 使用Keytool实用程序生成签名证书指纹
3. 使用您的应用程序包名称和步骤2中生成的指纹添加API密钥标识符（Android）。
4. 创建服务帐户。
5. 将您在上一步下载的JSon文件添加到项目的raw文件夹中。由于Android资源名称策略，您可能需要重命名它。
6. 获取您要访问的共享文件夹的ID（不确定您是否需要它）。

前三个步骤描述为here。第四步描述there。您可能需要Drive REST API文档。

然后代码......

我是在片段中做到的。我只是把重要的东西放在这里。我正在请求公用文件夹的文件列表。

import android.app.ProgressDialog;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBar;
import android.support.v7.widget.RecyclerView;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.File;
import com.google.api.services.drive.model.FileList;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;


public class FragmentDownload extends Fragment {

    GoogleCredential aCredential;
    ProgressDialog mProgress;

    /**
     * Required empty public constructor
     */
    public FragmentDownload() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_download, container, false);
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);    

        mProgress = new ProgressDialog(getContext());
        mProgress.setMessage("Calling Drive API ...");

        // Initialize credentials object.
        try {
            aCredential = GoogleCredential
                    .fromStream(getContext().getResources().openRawResource(R.raw.json_file))
                    .createScoped(DriveScopes.all());
        } catch (Exception e) {
            e.printStackTrace();
        }

        getResultsFromApi();
    }

    /**
     * Checks whether the device currently has a network connection.
     * @return true if the device has a network connection, false otherwise.
     */
    private boolean isDeviceOnline() {
        ConnectivityManager connMgr =
                (ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
        return (networkInfo != null && networkInfo.isConnected());
    }

    /**
     * Attempt to call the API, after verifying that all the preconditions are
     * satisfied. The preconditions are: Google Play Services installed, an
     * account was selected and the device currently has online access. If any
     * of the preconditions are not satisfied, the app will prompt the user as
     * appropriate.
     */
    private void getResultsFromApi() {
        if (! isDeviceOnline()) {
            Toast.makeText(getContext(), "No network connection available.", Toast.LENGTH_LONG).show();
        } else {
            new MakeRequestTask(aCredential).execute();
        }
    }

    /**
     * An asynchronous task that handles the Drive API call.
     * Placing the API calls in their own task ensures the UI stays responsive.
     */
    private class MakeRequestTask extends AsyncTask<Void, Void, List<String>> {
        private com.google.api.services.drive.Drive mService = null;
        private Exception mLastError = null;

        public MakeRequestTask(GoogleCredential credential) {
            HttpTransport transport = AndroidHttp.newCompatibleTransport();
            JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
            mService = new com.google.api.services.drive.Drive.Builder(
                    transport, jsonFactory, credential)
                    .setApplicationName("appName")
                    .build();

        }

        /**
         * Background task to call Drive API.
         * @param params no parameters needed for this task.
         */
        @Override
        protected List<String> doInBackground(Void... params) {
            try {
                return getDataFromApi();
            } catch (Exception e) {
                mLastError = e;
                cancel(true);
                return null;
            }
        }

        /**
         * Fetch a list of up to 10 file names and IDs.
         * @return List of Strings describing files, or an empty list if no files
         *         found.
         * @throws IOException
         */
        private List<String> getDataFromApi() throws IOException {
            // Get a list of up to 10 files.
            List<String> fileInfo = new ArrayList<>();
            FileList result = mService.files().list()
                    .setCorpus("user")
                    .setQ("'public_gdrive_folder_id' in parents")
                    .setOrderBy("name")
                    .setSpaces("drive")
                    .setFields("files(id, name)")
                    .execute();
            List<File> files = result.getFiles();
            if (files != null) {
                for (File file : files) {
                    fileInfo.add(String.format("%s (%s)\n",
                            file.getName(), file.getId()));
                }
            }
            return fileInfo;
        }


        @Override
        protected void onPreExecute() {
            mProgress.show();
        }

        @Override
        protected void onPostExecute(List<String> output) {
            mProgress.hide();
            if (output == null || output.size() == 0) {
                Toast.makeText(getContext(), "No results returned.", Toast.LENGTH_LONG).show();
            } else {
                //output.add(0, "Data retrieved using the Drive API:");
                Toast.makeText(getContext(), TextUtils.join("\n", output), Toast.LENGTH_LONG).show();
            }
        }

        @Override
        protected void onCancelled() {
            mProgress.hide();
            if (mLastError != null) {
                Toast.makeText(getContext(), "The following error occurred:\n"
                        + mLastError.getMessage(), Toast.LENGTH_LONG).show();

               // }
            } else {
                Toast.makeText(getContext(), "Request cancelled.", Toast.LENGTH_LONG).show();
            }
        }
    }

}