สร้างปุ่ม Facebook Login บน Android

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.facebook.widget.LoginButton
        android:id="@+id/facebookLoginButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="50dp" />

</LinearLayout>

<meta-data
    android:name="com.facebook.sdk.ApplicationId"
    android:value="@string/app_id" />

<activity android:name="com.facebook.LoginActivity" />

    <uses-permission
        android:name="android.permission.INTERNET" />

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

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="17" />

    <uses-permission
        android:name="android.permission.INTERNET" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.devahoy.facebooksdk.login.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>

        <meta-data
            android:name="com.facebook.sdk.ApplicationId"
            android:value="@string/app_id" />

        <activity android:name="com.facebook.LoginActivity" />
    </application>
</manifest>

private void onSessionStateChange(Session session, SessionState state, Exception exception) {
    if (state.isOpened()) {
        Log.i(TAG, "Logged in...");
    } else if (state.isClosed()) {
        Log.i(TAG, "Logged out...");
    }
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {
    private Session.StatusCallback callback = new Session.StatusCallback() {
        @Override
        public void call(Session session, SessionState state, Exception exception) {
            onSessionStateChange(session, state, exception);
        }
    };
...
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    uiHelper = new UiLifecycleHelper(getActivity(), callback);
    uiHelper.onCreate(savedInstanceState);
}

@Override
public void onResume() {
    super.onResume();
    uiHelper.onResume();
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    uiHelper.onActivityResult(requestCode, resultCode, data);
}

@Override
public void onPause() {
    super.onPause();
    uiHelper.onPause();
}

@Override
public void onDestroy() {
    super.onDestroy();
    uiHelper.onDestroy();
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    uiHelper.onSaveInstanceState(outState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_main, container,
            false);

    LoginButton authButton = (LoginButton) rootView.findViewById(R.id.facebookLoginButton);
    authButton.setFragment(this);
    return rootView;
}

@Override
public void onResume() {
    super.onResume();

    Session session = Session.getActiveSession();
    if (session != null &&
           (session.isOpened() || session.isClosed()) ) {
        onSessionStateChange(session, session.getState(), null);
    }

    uiHelper.onResume();
}

private void onSessionStateChange(Session session, SessionState state, Exception exception) {
    if (state.isOpened()) {

        Request request = Request.newMeRequest(session, new GraphUserCallback() {

            @Override
            public void onCompleted(GraphUser user, Response response) {
                Toast.makeText(getActivity(),
                        "Hello " + user.getName(),
                        Toast.LENGTH_LONG).show();
            }
        });
        request.executeAsync();

    } else if (state.isClosed()) {
        Log.i(TAG, "Logged out...");
    }
}

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

        <uses-sdk
            android:minSdkVersion="11"
            android:targetSdkVersion="17" />

       <uses-permission
            android:name="android.permission.INTERNET" />

        <application
            android:allowBackup="true"
            android:icon="@drawable/ic_launcher"
            android:label="@string/app_name"
            android:theme="@style/AppTheme" >
            <activity
                android:name="com.devahoy.facebooksdk.login.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>

            <meta-data
                android:name="com.facebook.sdk.ApplicationId"
                android:value="@string/app_id" />

            <activity android:name="com.facebook.LoginActivity" />
        </application>

    </manifest>

`fragment_main.xml`

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <com.facebook.widget.LoginButton
            android:id="@+id/facebookLoginButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_marginTop="50dp" />

    </LinearLayout>

package com.devahoy.facebooksdk.login;

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import com.facebook.Request;
import com.facebook.Request.GraphUserCallback;
import com.facebook.Response;
import com.facebook.Session;
import com.facebook.SessionState;
import com.facebook.UiLifecycleHelper;
import com.facebook.model.GraphUser;
import com.facebook.widget.LoginButton;

public class MainActivity extends ActionBarActivity {

    private static String TAG = MainActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        private UiLifecycleHelper uiHelper;
        private Session.StatusCallback callback = new Session.StatusCallback() {
            @Override
            public void call(Session session, SessionState state, Exception exception) {
                onSessionStateChange(session, state, exception);
            }
        };

        public PlaceholderFragment() {
        }

        private void onSessionStateChange(Session session, SessionState state, Exception exception) {
            if (state.isOpened()) {

                Request request = Request.newMeRequest(session, new GraphUserCallback() {

                    @Override
                    public void onCompleted(GraphUser user, Response response) {
                        Toast.makeText(getActivity(),
                                "Hello " + user.getName(),
                                Toast.LENGTH_LONG).show();
                    }
                });
                request.executeAsync();

            } else if (state.isClosed()) {
                Log.i(TAG, "Logged out...");
            }
        }

        @Override
        public void onResume() {
            super.onResume();

            Session session = Session.getActiveSession();
            if (session != null &&
                   (session.isOpened() || session.isClosed()) ) {
                onSessionStateChange(session, session.getState(), null);
            }

            uiHelper.onResume();
        }

        @Override
        public void onActivityResult(int requestCode, int resultCode, Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
            uiHelper.onActivityResult(requestCode, resultCode, data);
        }

        @Override
        public void onPause() {
            super.onPause();
            uiHelper.onPause();
        }

        @Override
        public void onDestroy() {
            super.onDestroy();
            uiHelper.onDestroy();
        }

        @Override
        public void onSaveInstanceState(Bundle outState) {
            super.onSaveInstanceState(outState);
            uiHelper.onSaveInstanceState(outState);
        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            uiHelper = new UiLifecycleHelper(getActivity(), callback);
            uiHelper.onCreate(savedInstanceState);
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);

            LoginButton authButton = (LoginButton) rootView.findViewById(R.id.facebookLoginButton);
            authButton.setFragment(this);
            return rootView;
        }

    }

}