程式碼實現 Google SignIn

• 在登入活動的 onCreate 方法中，配置 Google 登入以請求你的應用所需的使用者資料。

 GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
        .requestEmail()
        .build();

• 建立一個 GoogleApiClient 物件，可以訪問 Google 登入 API 和你指定的選項。

 mGoogleApiClient = new GoogleApiClient.Builder(this)
        .enableAutoManage(this /* FragmentActivity */, this /* OnConnectionFailedListener */)
        .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
        .build();

• 現在，當使用者點選 Google 登入按鈕時，請呼叫此功能。

   private void signIn() {
   Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
   startActivityForResult(signInIntent, RC_SIGN_IN);
  }
  

• 實現 OnActivityResult 以獲取響應。

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

    // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
    if (requestCode == RC_SIGN_IN) {
        GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
        handleSignInResult(result);
    }
}

• 最後一步處理結果並獲取使用者資料

   private void handleSignInResult(GoogleSignInResult result) {
   Log.d(TAG, "handleSignInResult:" + result.isSuccess());
   if (result.isSuccess()) {
       // Signed in successfully, show authenticated UI.
       GoogleSignInAccount acct = result.getSignInAccount();
       mStatusTextView.setText(getString(R.string.signed_in_fmt, acct.getDisplayName()));
       updateUI(true);
   } else {
       // Signed out, show unauthenticated UI.
       updateUI(false);
   }
  }