Android: Google authentication

Question

I want to ask, what is the best way to authenticate user with his Google account already configured on the phone. I have looked at the ClientLogin first, but it's not what I want because it requires users to enter login/password in my application. I can do it with OAuth but there I should ask user to enter his credentials in browser what is not preferable too. I want to use AccountManager (I've observed that it contains method getPassword for particular account but it didn't work for me), if it's possible to use somehow AccountManager + ClientLogin or AccountManager + OAuth tell me please. In result I want to have capabilities to log in with user Google account without asking his login/password (with confirmation on android device of course) I am not sure that it's possible but if there exists some way to implement this please point me how...

Answer 1

yes, you can access information in the accountManager and authenticate the user using registered google account (for example) without her entering password.

the code below is a functional mix and match from examples by nick johnson and by tencent

start with your main activity:

    package com.tg.auth;

import android.accounts.Account;
import android.accounts.AccountManager;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class ZAuth02aActivity extends ListActivity {
    protected AccountManager accountManager;
    protected Intent intent;
    String TAG = "TGtracker";

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        accountManager = AccountManager.get(getApplicationContext());
        Account[] accounts = accountManager.getAccountsByType("com.google");
        this.setListAdapter(new ArrayAdapter<Account>(this, R.layout.list_item, accounts));        

    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        Account account = (Account)getListView().getItemAtPosition(position);
        Intent intent = new Intent(this, AppInfo.class);
        intent.putExtra("account", account);
        startActivity(intent);
    }
}

create an AppInfo class:

    package com.tg.auth;


import org.apache.http.impl.client.DefaultHttpClient;

import android.accounts.Account;
import android.accounts.AccountManager;
import android.accounts.AccountManagerFuture;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class AppInfo extends Activity {
    DefaultHttpClient http_client = new DefaultHttpClient();
    Activity activity;
    String TAG = "TGtracker";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.app_info);
        activity = this;

    }

    @Override
    protected void onResume() {
        super.onResume();
        //Log.v(TAG, "resuming activity");
        AccountManager accountManager = AccountManager.get(getApplicationContext());
        //if result is null, you might not have a valid internet connection
        Log.i(TAG, "got token, yipee: "+updateToken(accountManager, true));
    }


    private String updateToken(AccountManager am, boolean invalidateToken) {
        String authToken = "null";
        try {
            Account[] accounts = am.getAccountsByType("com.google");
            AccountManagerFuture<Bundle> accountManagerFuture;
            if(activity == null){//this is used when calling from an interval thread
                accountManagerFuture = am.getAuthToken(accounts[0], "android", false, null, null);
            } else {
                accountManagerFuture = am.getAuthToken(accounts[0], "android", null, activity, null, null);
            }
            Bundle authTokenBundle = accountManagerFuture.getResult();
            authToken = authTokenBundle.getString(AccountManager.KEY_AUTHTOKEN).toString();
            Log.v(TAG, "newToken preinvalidate: "+authToken);

            if(invalidateToken) {
                am.invalidateAuthToken("com.google", authToken);
                authToken = updateToken(am, false);

            }
        } catch (IOException e) {
            Log.e(TAG, "the exception was: "+e.toString());
            e.printStackTrace();
        }
        return authToken;
    }
}

use a manifest file, somewhat like this (must declare activities + permissions):

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.tg.auth"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="7" />
    <uses-permission android:name="android.permission.MANAGE_ACCOUNTS"></uses-permission>
    <uses-permission android:name="android.permission.GET_ACCOUNTS"></uses-permission>
    <uses-permission android:name="android.permission.USE_CREDENTIALS"></uses-permission>
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".ZAuth02aActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".AppInfo"></activity>
    </application>

</manifest>

use nick johnson's layout files that you can download here