我的MainActivity.java：
package com.example.drivesync;
import com.google.android.gms.auth.api.signin.GoogleSignIn;
import com.google.android.gms.auth.api.signin.GoogleSignInClient;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.common.api.Scope;
import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.File;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.EditText;
import java.util.Collections;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private static final int REQUEST_CODE_SIGN_IN = 1;
private static final int REQUEST_CODE_OPEN_DOCUMENT = 2;
private DriveServiceHelper mDriveServiceHelper;
private String mOpenFileId;
private EditText mFileTitleEditText;
private EditText mDocContentEditText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Store the EditText boxes to be updated when files are opened/created/modified.
mFileTitleEditText = findViewById(R.id.file_title_edittext);
mDocContentEditText = findViewById(R.id.doc_content_edittext);
// Set the onClick listeners for the button bar.
findViewById(R.id.open_btn).setOnClickListener(view -> openFilePicker());
findViewById(R.id.create_btn).setOnClickListener(view -> createFile());
findViewById(R.id.save_btn).setOnClickListener(view -> saveFile());
findViewById(R.id.query_btn).setOnClickListener(view -> query());
// Authenticate the user. For most apps, this should be done when the user performs an
// action that requires Drive access rather than in onCreate.
requestSignIn(); // Account Auswahl
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent resultData) {
switch (requestCode) {
case REQUEST_CODE_SIGN_IN:
if (resultCode == Activity.RESULT_OK && resultData != null) {
handleSignInResult(resultData);
}
break;
case REQUEST_CODE_OPEN_DOCUMENT:
if (resultCode == Activity.RESULT_OK && resultData != null) {
//Uri uri = resultData.getData();
/*if (uri != null) {
openFileFromFilePicker(uri);
}*/
}
break;
}
//super.onActivityResult(requestCode, resultCode, resultData);
}
/**
* Starts a sign-in activity using {@link #REQUEST_CODE_SIGN_IN}.
*/
private void requestSignIn() {
GoogleSignInOptions signInOptions =
new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
.requestEmail()
.requestScopes(new Scope(DriveScopes.DRIVE_FILE))
.build();
GoogleSignInClient client = GoogleSignIn.getClient(this, signInOptions);
// The result of the sign-in Intent is handled in onActivityResult.
startActivityForResult(client.getSignInIntent(), REQUEST_CODE_SIGN_IN);
}
/**
* Handles the {@code result} of a completed sign-in activity initiated from {@link
* #requestSignIn()}.
*/
private void handleSignInResult(Intent result) {
GoogleSignIn.getSignedInAccountFromIntent(result)
.addOnSuccessListener(googleAccount -> {
Log.d(TAG, "Signed in as " + googleAccount.getEmail());
// Use the authenticated account to sign in to the Drive service.
GoogleAccountCredential credential =
GoogleAccountCredential.usingOAuth2(
this, Collections.singleton(DriveScopes.DRIVE_FILE));
credential.setSelectedAccount(googleAccount.getAccount());
Drive googleDriveService =
new Drive.Builder(
AndroidHttp.newCompatibleTransport(),
new GsonFactory(),
credential)
.setApplicationName("Drive API Migration")
.build();
// The DriveServiceHelper encapsulates all REST API and SAF functionality.
// Its instantiation is required before handling any onClick actions.
mDriveServiceHelper = new DriveServiceHelper(googleDriveService);
})
.addOnFailureListener(exception -> Log.e(TAG, "Unable to sign in.", exception));
}
/**
* Opens the Storage Access Framework file picker using {@link #REQUEST_CODE_OPEN_DOCUMENT}.
*/
private void openFilePicker()
{
if (mDriveServiceHelper != null)
{
Intent pickerIntent = mDriveServiceHelper.createFilePickerIntent();
// The result of the SAF Intent is handled in onActivityResult.
startActivityForResult(pickerIntent, REQUEST_CODE_OPEN_DOCUMENT);
}
}
/**
* Opens a file from its {@code uri} returned from the Storage Access Framework file picker
* initiated by {@link #openFilePicker()}.
*/
private void openFileFromFilePicker(Uri uri)
{
if (mDriveServiceHelper != null)
{
mDriveServiceHelper.openFileUsingStorageAccessFramework(getContentResolver(), uri)
.addOnSuccessListener(nameAndContent -> {
String name = nameAndContent.first;
String content = nameAndContent.second;
mFileTitleEditText.setText(name);
mDocContentEditText.setText(content);
// Files opened through SAF cannot be modified.
setReadOnlyMode();
})
.addOnFailureListener(exception ->
Log.e(TAG, "Unable to open file from picker.", exception));
}
}
/**
* Creates a new file via the Drive REST API.
*/
private void createFile() {
if (mDriveServiceHelper != null) {
Log.d(TAG, "Creating a file.");
mDriveServiceHelper.createFile()
.addOnSuccessListener(fileId -> readFile(fileId))
.addOnFailureListener(exception ->
Log.e(TAG, "Couldn't create file.", exception));
}
}
/**
* Retrieves the title and content of a file identified by {@code fileId} and populates the UI.
*/
private void readFile(String fileId) {
if (mDriveServiceHelper != null) {
Log.d(TAG, "Reading file " + fileId);
mDriveServiceHelper.readFile(fileId)
.addOnSuccessListener(nameAndContent -> {
String name = nameAndContent.first;
String content = nameAndContent.second;
mFileTitleEditText.setText(name);
mDocContentEditText.setText(content);
setReadWriteMode(fileId);
})
.addOnFailureListener(exception ->
Log.e(TAG, "Couldn't read file.", exception));
}
}
/**
* Saves the currently opened file created via {@link #createFile()} if one exists.
*/
private void saveFile() {
if (mDriveServiceHelper != null && mOpenFileId != null) {
Log.d(TAG, "Saving " + mOpenFileId);
String fileName = mFileTitleEditText.getText().toString();
String fileContent = mDocContentEditText.getText().toString();
mDriveServiceHelper.saveFile(mOpenFileId, fileName, fileContent)
.addOnFailureListener(exception ->
Log.e(TAG, "Unable to save file via REST.", exception));
}
}
/**
* Queries the Drive REST API for files visible to this app and lists them in the content view.
*/
private void query() {
if (mDriveServiceHelper != null) {
Log.d(TAG, "Querying for files.");
mDriveServiceHelper.queryFiles()
.addOnSuccessListener(fileList -> {
StringBuilder builder = new StringBuilder();
for (File file : fileList.getFiles()) {
builder.append(file.getName()).append("\n");
}
String fileNames = builder.toString();
mFileTitleEditText.setText("File List");
mDocContentEditText.setText(fileNames);
setReadOnlyMode();
})
.addOnFailureListener(exception -> Log.e(TAG, "Unable to query files.", exception));
}
}
/**
* Updates the UI to read-only mode.
*/
private void setReadOnlyMode() {
mFileTitleEditText.setEnabled(false);
mDocContentEditText.setEnabled(false);
mOpenFileId = null;
}
/**
* Updates the UI to read/write mode on the document identified by {@code fileId}.
*/
private void setReadWriteMode(String fileId) {
mFileTitleEditText.setEnabled(true);
mDocContentEditText.setEnabled(true);
mOpenFileId = fileId;
}
}
因此，我使用FilePicker打开Intent pickerIntent = mDriveServiceHelper.createFilePickerIntent();并使用startActivityForResult(pickerIntent, REQUEST_CODE_OPEN_DOCUMENT);运行它们。这将打开一个文件选择对话框，并被选为标准的最新文档。我可以在Google帐户，最新文件和设备存储之间进行选择。我想将标准设置为我的Google帐户之一，而不是最近的文件。我该怎么办？