问题
I am following this tutorial https://developers.google.com/+/mobile/android/recommend to integrate +1 button in my app.
As soon as I put this code in xml I get errors in GraphicalLayout
<com.google.android.gms.plus.PlusOneButton
xmlns:plus="http://schemas.android.com/apk/lib/com.google.android.gms.plus"
android:id="@+id/plus_one_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
plus:size="standard"
plus:annotation="inline" />
I also tried putting xmlns:plus="http://schemas.android.com/apk/lib/com.google.android.gms.plus" in parent RelativeLayout, but the same error.
The following classes could not be instantiated:
- com.google.android.gms.plus.PlusOneButton (Open Class, Show Error Log)
See the Error Log (Window > Show View) for more details.
java.lang.NullPointerException
at com.google.android.gms.plus.PlusOneDummyView$zzb.isValid( at com.google.android.gms.plus.PlusOneDummyView.zzrJ( at com.google.android.gms.plus.PlusOneDummyView.<init>( at com.google.android.gms.plus.internal.zzg.zza( at com.google.android.gms.plus.PlusOneButton.zzN( at com.google.android.gms.plus.PlusOneButton.<init>( at sun.reflect.NativeConstructorAccessorImpl.newInstance0( at sun.reflect.NativeConstructorAccessorImpl.newInstance( at sun.reflect.DelegatingConstructorAccessorImpl.newInstance( at java.lang.reflect.Constructor.newInstance( at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(ProjectCallback.java:438)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(ProjectCallback.java:190)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:207)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:132)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:806)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:782)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:385)
Help !!
回答1:
Android Studio solution:
I just got a simple example working by starting with the code from the gplus-quickstart, and then adding a +1 button using the guide linked in the question.
build.gradle dependencies:
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:22.1.1'
compile 'com.google.android.gms:play-services:7.0.0'
}
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.plustest.daniel.googleplusone" >
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
</manifest>
I added com.google.android.gms.plus.PlusOneButton to the bottom of activity_main.xml, which is based on main_activity.xml from the quick start code:
xmlns:plus="http://schemas.android.com/apk/lib/com.google.android.gms.plus"
android:id="@+id/plus_one_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
plus:size="standard"
plus:annotation="inline" />
MainActivity.java, with the added +1 button.
Note that for URL I used the Carnegie Mellon School of Computer Science Google+ page.
public class MainActivity extends FragmentActivity implements
ConnectionCallbacks, OnConnectionFailedListener,
ResultCallback<LoadPeopleResult>, View.OnClickListener,
CheckBox.OnCheckedChangeListener, GoogleApiClient.ServerAuthCodeCallbacks {
private static final String TAG = "android-plus-quickstart";
private static final int STATE_DEFAULT = 0;
private static final int STATE_SIGN_IN = 1;
private static final int STATE_IN_PROGRESS = 2;
private static final int RC_SIGN_IN = 0;
private static final String SAVED_PROGRESS = "sign_in_progress";
// Client ID for a web server that will receive the auth code and exchange it for a
// refresh token if offline access is requested.
private static final String WEB_CLIENT_ID = "WEB_CLIENT_ID";
// Base URL for your token exchange server, no trailing slash.
private static final String SERVER_BASE_URL = "SERVER_BASE_URL";
// URL where the client should GET the scopes that the server would like granted
// before asking for a serverAuthCode
private static final String EXCHANGE_TOKEN_URL = SERVER_BASE_URL + "/exchangetoken";
// URL where the client should POST the serverAuthCode so that the server can exchange
// it for a refresh token,
private static final String SELECT_SCOPES_URL = SERVER_BASE_URL + "/selectscopes";
private int mSignInProgress;
// Used to store the PendingIntent most recently returned by Google Play
// services until the user clicks 'sign in'.
private PendingIntent mSignInIntent;
// Used to store the error code most recently returned by Google Play services
// until the user clicks 'sign in'.
private int mSignInError;
// Used to determine if we should ask for a server auth code when connecting the
// GoogleApiClient. False by default so that this sample can be used without configuring
// a WEB_CLIENT_ID and SERVER_BASE_URL.
private boolean mRequestServerAuthCode = false;
// Used to mock the state of a server that would receive an auth code to exchange
// for a refresh token, If true, the client will assume that the server has the
// permissions it wants and will not send an auth code on sign in. If false,
// the client will request offline access on sign in and send and new auth code
// to the server. True by default because this sample does not implement a server
// so there would be nowhere to send the code.
private boolean mServerHasToken = true;
private SignInButton mSignInButton;
private Button mSignOutButton;
private Button mRevokeButton;
private TextView mStatus;
private ListView mCirclesListView;
private ArrayAdapter<String> mCirclesAdapter;
private ArrayList<String> mCirclesList;
//added:
private PlusOneButton mPlusOneButton;
private String URL = "https://plus.google.com/101009371381835899795/posts";
private static final int PLUS_ONE_REQUEST_CODE = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mSignInButton = (SignInButton) findViewById(R.id.sign_in_button);
mSignOutButton = (Button) findViewById(R.id.sign_out_button);
mRevokeButton = (Button) findViewById(R.id.revoke_access_button);
mStatus = (TextView) findViewById(R.id.sign_in_status);
mCirclesListView = (ListView) findViewById(R.id.circles_list);
//added:
mPlusOneButton = (PlusOneButton) findViewById(R.id.plus_one_button);
// Button listeners
mSignInButton.setOnClickListener(this);
mSignOutButton.setOnClickListener(this);
mRevokeButton.setOnClickListener(this);
// CheckBox listeners
((CheckBox) findViewById(R.id.request_auth_code_checkbox)).setOnCheckedChangeListener(this);
((CheckBox) findViewById(R.id.has_token_checkbox)).setOnCheckedChangeListener(this);
mCirclesList = new ArrayList<String>();
mCirclesAdapter = new ArrayAdapter<String>(
this, R.layout.circle_member, mCirclesList);
mCirclesListView.setAdapter(mCirclesAdapter);
if (savedInstanceState != null) {
mSignInProgress = savedInstanceState
.getInt(SAVED_PROGRESS, STATE_DEFAULT);
}
mGoogleApiClient = buildGoogleApiClient();
}
private GoogleApiClient buildGoogleApiClient() {
// When we build the GoogleApiClient we specify where connected and
// connection failed callbacks should be returned, which Google APIs our
// app uses and which OAuth 2.0 scopes our app requests.
GoogleApiClient.Builder builder = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(Plus.API, Plus.PlusOptions.builder().build())
.addScope(Plus.SCOPE_PLUS_LOGIN);
if (mRequestServerAuthCode) {
checkServerAuthConfiguration();
builder = builder.requestServerAuthCode(WEB_CLIENT_ID, this);
}
return builder.build();
}
//added:
@Override
protected void onResume() {
super.onResume();
// Refresh the state of the +1 button each time the activity receives focus.
mPlusOneButton.initialize(URL, PLUS_ONE_REQUEST_CODE);
}
@Override
protected void onStart() {
super.onStart();
mGoogleApiClient.connect();
}
@Override
protected void onStop() {
super.onStop();
if (mGoogleApiClient.isConnected()) {
mGoogleApiClient.disconnect();
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt(SAVED_PROGRESS, mSignInProgress);
}
@Override
public void onClick(View v) {
if (!mGoogleApiClient.isConnecting()) {
// We only process button clicks when GoogleApiClient is not transitioning
// between connected and not connected.
switch (v.getId()) {
case R.id.sign_in_button:
mStatus.setText(R.string.status_signing_in);
mSignInProgress = STATE_SIGN_IN;
mGoogleApiClient.connect();
break;
case R.id.sign_out_button:
// We clear the default account on sign out so that Google Play
// services will not return an onConnected callback without user
// interaction.
if (mGoogleApiClient.isConnected()) {
Plus.AccountApi.clearDefaultAccount(mGoogleApiClient);
mGoogleApiClient.disconnect();
}
onSignedOut();
break;
case R.id.revoke_access_button:
// After we revoke permissions for the user with a GoogleApiClient
// instance, we must discard it and create a new one.
Plus.AccountApi.clearDefaultAccount(mGoogleApiClient);
// Our sample has caches no user data from Google+, however we
// would normally register a callback on revokeAccessAndDisconnect
// to delete user data so that we comply with Google developer
// policies.
Plus.AccountApi.revokeAccessAndDisconnect(mGoogleApiClient);
mGoogleApiClient = buildGoogleApiClient();
mGoogleApiClient.connect();
break;
}
}
}
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
switch (buttonView.getId()) {
case R.id.request_auth_code_checkbox:
mRequestServerAuthCode = isChecked;
buildGoogleApiClient();
if (isChecked) {
findViewById(R.id.layout_has_token).setVisibility(View.VISIBLE);
} else {
findViewById(R.id.layout_has_token).setVisibility(View.INVISIBLE);
}
break;
case R.id.has_token_checkbox:
mServerHasToken = isChecked;
break;
}
}
/* onConnected is called when our Activity successfully connects to Google
* Play services. onConnected indicates that an account was selected on the
* device, that the selected account has granted any requested permissions to
* our app and that we were able to establish a service connection to Google
* Play services.
*/
@Override
public void onConnected(Bundle connectionHint) {
// Reaching onConnected means we consider the user signed in.
Log.i(TAG, "onConnected");
// Update the user interface to reflect that the user is signed in.
mSignInButton.setEnabled(false);
mSignOutButton.setEnabled(true);
mRevokeButton.setEnabled(true);
// Hide the sign-in options, they no longer apply
findViewById(R.id.layout_server_auth).setVisibility(View.GONE);
// Retrieve some profile information to personalize our app for the user.
Person currentUser = Plus.PeopleApi.getCurrentPerson(mGoogleApiClient);
mStatus.setText(String.format(
getResources().getString(R.string.signed_in_as),
currentUser.getDisplayName()));
Plus.PeopleApi.loadVisible(mGoogleApiClient, null)
.setResultCallback(this);
// Indicate that the sign in process is complete.
mSignInProgress = STATE_DEFAULT;
}
/* onConnectionFailed is called when our Activity could not connect to Google
* Play services. onConnectionFailed indicates that the user needs to select
* an account, grant permissions or resolve an error in order to sign in.
*/
@Override
public void onConnectionFailed(ConnectionResult result) {
// Refer to the javadoc for ConnectionResult to see what error codes might
// be returned in onConnectionFailed.
Log.i(TAG, "onConnectionFailed: ConnectionResult.getErrorCode() = "
+ result.getErrorCode());
if (result.getErrorCode() == ConnectionResult.API_UNAVAILABLE) {
// An API requested for GoogleApiClient is not available. The device's current
// configuration might not be supported with the requested API or a required component
// may not be installed, such as the Android Wear application. You may need to use a
// second GoogleApiClient to manage the application's optional APIs.
Log.w(TAG, "API Unavailable.");
} else if (mSignInProgress != STATE_IN_PROGRESS) {
// We do not have an intent in progress so we should store the latest
// error resolution intent for use when the sign in button is clicked.
mSignInIntent = result.getResolution();
mSignInError = result.getErrorCode();
if (mSignInProgress == STATE_SIGN_IN) {
// STATE_SIGN_IN indicates the user already clicked the sign in button
// so we should continue processing errors until the user is signed in
// or they click cancel.
resolveSignInError();
}
}
// In this sample we consider the user signed out whenever they do not have
// a connection to Google Play services.
onSignedOut();
}
private void resolveSignInError() {
if (mSignInIntent != null) {
// We have an intent which will allow our user to sign in or
// resolve an error. For example if the user needs to
// select an account to sign in with, or if they need to consent
// to the permissions your app is requesting.
try {
// Send the pending intent that we stored on the most recent
// OnConnectionFailed callback. This will allow the user to
// resolve the error currently preventing our connection to
// Google Play services.
mSignInProgress = STATE_IN_PROGRESS;
startIntentSenderForResult(mSignInIntent.getIntentSender(),
RC_SIGN_IN, null, 0, 0, 0);
} catch (SendIntentException e) {
Log.i(TAG, "Sign in intent could not be sent: "
+ e.getLocalizedMessage());
// The intent was canceled before it was sent. Attempt to connect to
// get an updated ConnectionResult.
mSignInProgress = STATE_SIGN_IN;
mGoogleApiClient.connect();
}
} else {
// Google Play services wasn't able to provide an intent for some
// error types, so we show the default Google Play services error
// dialog which may still start an intent on our behalf if the
// user can resolve the issue.
createErrorDialog().show();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode,
Intent data) {
switch (requestCode) {
case RC_SIGN_IN:
if (resultCode == RESULT_OK) {
// If the error resolution was successful we should continue
// processing errors.
mSignInProgress = STATE_SIGN_IN;
} else {
// If the error resolution was not successful or the user canceled,
// we should stop processing errors.
mSignInProgress = STATE_DEFAULT;
}
if (!mGoogleApiClient.isConnecting()) {
// If Google Play services resolved the issue with a dialog then
// onStart is not called so we need to re-attempt connection here.
mGoogleApiClient.connect();
}
break;
}
}
@Override
public void onResult(LoadPeopleResult peopleData) {
if (peopleData.getStatus().getStatusCode() == CommonStatusCodes.SUCCESS) {
mCirclesList.clear();
PersonBuffer personBuffer = peopleData.getPersonBuffer();
try {
int count = personBuffer.getCount();
for (int i = 0; i < count; i++) {
mCirclesList.add(personBuffer.get(i).getDisplayName());
}
} finally {
personBuffer.close();
}
mCirclesAdapter.notifyDataSetChanged();
} else {
Log.e(TAG, "Error requesting visible circles: " + peopleData.getStatus());
}
}
private void onSignedOut() {
// Update the UI to reflect that the user is signed out.
mSignInButton.setEnabled(true);
mSignOutButton.setEnabled(false);
mRevokeButton.setEnabled(false);
// Show the sign-in options
findViewById(R.id.layout_server_auth).setVisibility(View.VISIBLE);
mStatus.setText(R.string.status_signed_out);
mCirclesList.clear();
mCirclesAdapter.notifyDataSetChanged();
}
@Override
public void onConnectionSuspended(int cause) {
// The connection to Google Play services was lost for some reason.
// We call connect() to attempt to re-establish the connection or get a
// ConnectionResult that we can attempt to resolve.
mGoogleApiClient.connect();
}
private Dialog createErrorDialog() {
if (GooglePlayServicesUtil.isUserRecoverableError(mSignInError)) {
return GooglePlayServicesUtil.getErrorDialog(
mSignInError,
this,
RC_SIGN_IN,
new DialogInterface.OnCancelListener() {
@Override
public void onCancel(DialogInterface dialog) {
Log.e(TAG, "Google Play services resolution cancelled");
mSignInProgress = STATE_DEFAULT;
mStatus.setText(R.string.status_signed_out);
}
});
} else {
return new AlertDialog.Builder(this)
.setMessage(R.string.play_services_error)
.setPositiveButton(R.string.close,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Log.e(TAG, "Google Play services error could not be "
+ "resolved: " + mSignInError);
mSignInProgress = STATE_DEFAULT;
mStatus.setText(R.string.status_signed_out);
}
}).create();
}
}
@Override
public CheckResult onCheckServerAuthorization(String idToken, Set<Scope> scopeSet) {
Log.i(TAG, "Checking if server is authorized.");
Log.i(TAG, "Mocking server has refresh token: " + String.valueOf(mServerHasToken));
if (!mServerHasToken) {
// Server does not have a valid refresh token, so request a new
// auth code which can be exchanged for one. This will cause the user to see the
// consent dialog and be prompted to grant offline access. This callback occurs on a
// background thread so it is OK to do synchronous network access.
// Ask the server which scopes it would like to have for offline access. This
// can be distinct from the scopes granted to the client. By getting these values
// from the server, you can change your server's permissions without needing to
// recompile the client application.
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(SELECT_SCOPES_URL);
HashSet<Scope> serverScopeSet = new HashSet<Scope>();
try {
HttpResponse httpResponse = httpClient.execute(httpGet);
int responseCode = httpResponse.getStatusLine().getStatusCode();
String responseBody = EntityUtils.toString(httpResponse.getEntity());
if (responseCode == 200) {
String[] scopeStrings = responseBody.split(" ");
for (String scope : scopeStrings) {
Log.i(TAG, "Server Scope: " + scope);
serverScopeSet.add(new Scope(scope));
}
} else {
Log.e(TAG, "Error in getting server scopes: " + responseCode);
}
} catch (ClientProtocolException e) {
Log.e(TAG, "Error in getting server scopes.", e);
} catch (IOException e) {
Log.e(TAG, "Error in getting server scopes.", e);
}
// This tells GoogleApiClient that the server needs a new serverAuthCode with
// access to the scopes in serverScopeSet. Note that we are not asking the server
// if it already has such a token because this is a sample application. In reality,
// you should only do this on the first user sign-in or if the server loses or deletes
// the refresh token.
return CheckResult.newAuthRequiredResult(serverScopeSet);
} else {
// Server already has a valid refresh token with the correct scopes, no need to
// ask the user for offline access again.
return CheckResult.newAuthNotRequiredResult();
}
}
@Override
public boolean onUploadServerAuthCode(String idToken, String serverAuthCode) {
// Upload the serverAuthCode to the server, which will attempt to exchange it for
// a refresh token. This callback occurs on a background thread, so it is OK
// to perform synchronous network access. Returning 'false' will fail the
// GoogleApiClient.connect() call so if you would like the client to ignore
// server failures, always return true.
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(EXCHANGE_TOKEN_URL);
try {
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
nameValuePairs.add(new BasicNameValuePair("serverAuthCode", serverAuthCode));
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpClient.execute(httpPost);
int statusCode = response.getStatusLine().getStatusCode();
final String responseBody = EntityUtils.toString(response.getEntity());
Log.i(TAG, "Code: " + statusCode);
Log.i(TAG, "Resp: " + responseBody);
// Show Toast on UI Thread
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(MainActivity.this, responseBody, Toast.LENGTH_LONG).show();
}
});
return (statusCode == 200);
} catch (ClientProtocolException e) {
Log.e(TAG, "Error in auth code exchange.", e);
return false;
} catch (IOException e) {
Log.e(TAG, "Error in auth code exchange.", e);
return false;
}
}
private void checkServerAuthConfiguration() {
// Check that the server URL is configured before allowing this box to
// be unchecked
if ("WEB_CLIENT_ID".equals(WEB_CLIENT_ID) ||
"SERVER_BASE_URL".equals(SERVER_BASE_URL)) {
Log.w(TAG, "WEB_CLIENT_ID or SERVER_BASE_URL configured incorrectly.");
Dialog dialog = new AlertDialog.Builder(this)
.setMessage(getString(R.string.configuration_error))
.setNeutralButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
})
.create();
dialog.show();
}
}
}
Result after signing in and clicking the +1 button:
回答2:
Add compile 'com.google.android.gms:play-services-plus:10.0.1' to your app's gradle
来源：https://stackoverflow.com/questions/30451679/the-following-classes-could-not-be-instantiated-com-google-android-gms-plus-p