在活动之外封装一个启动活动的方法答案

【问题标题】：Encapsulate a method that start an activity, outside an activity在活动之外封装一个启动活动的方法
【发布时间】：2019-03-17 10:50:32
【问题描述】：

我正在尝试创建一种在 Firebase 上对 Google 用户进行身份验证的方法。

我在 3 个不同的活动中使用此方法，我想清理创建方法的代码。

这是我试图在类中作为静态方法制作的代码。

  private void firebaseAuthWithGoogle(GoogleSignInAccount acct, final Context activity, FirebaseAuth firebaseAuth) {
        Log.d("MainACtivity", "firebaseAuthWithGoogle:" + acct.getId());

        AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
        firebaseAuth.signInWithCredential(credential)
                .addOnCompleteListener(activity, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        Log.d("Main", "signInWithCredential:onComplete:" + task.isSuccessful());

                        if (!task.isSuccessful()) {
                            Log.w("MainAcitivyt", "signInWithCredential", task.getException());
                            Toast.makeText(activity, "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();
                        }
                        else{
                            startActivity(AccountCreationActivity.newIntent(activity));
                        }
                    }
                });
    }

当我的方法被调用时，我无法理解如何使用另一个类的“startActivity”。或者我也一直在尝试的第二个选择是返回一个意图，但是由于“onComplete”返回无效，我完全失去了如何继续。

这是我的 Google 注册/登录代码，我想在不同的活动中复制它，并计划在另一个类中创建它的方法。我认为我无法从我的注册活动中取出的唯一方法是“onACtivityResult”

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

    @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) {
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            try {
                // Google Sign In was successful, authenticate with Firebase
                GoogleSignInAccount account = task.getResult(ApiException.class);
                firebaseAuthWithGoogle(account);
            } catch (ApiException e) {
                // Google Sign In failed, update UI appropriately
                Log.w(TAG, "Google sign in failed", e);
                // ...
            }
        }
    }
    private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {
        Log.d("MainACtivity", "firebaseAuthWithGoogle:" + acct.getId());

        AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
        firebaseAuth.signInWithCredential(credential)
                .addOnCompleteListener(getActivity(), new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        Log.d("Main", "signInWithCredential:onComplete:" + task.isSuccessful());

                        // If sign in fails, display a message to the user. If sign in succeeds
                        // the auth state listener will be notified and logic to handle the
                        // signed in user can be handled in the listener.
                        if (!task.isSuccessful()) {
                            Log.w("MainAcitivyt", "signInWithCredential", task.getException());
                            Toast.makeText(getActivity(), "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();
                        }
                        else{
                            startActivity(AccountCreationActivity.newIntent(getActivity()));
                        }
                    }
                });
    }

【问题讨论】：

标签： android authentication android-intent google-authentication

【解决方案1】：

如何使用另一个类的“startActivity”

使用Context 的实例开始活动。你在方法参数中有Context activity，使用它。

private void firebaseAuthWithGoogle(GoogleSignInAccount acct, final Context activity, FirebaseAuth firebaseAuth) {
        Log.d("MainACtivity", "firebaseAuthWithGoogle:" + acct.getId());

        AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
        firebaseAuth.signInWithCredential(credential)
                .addOnCompleteListener(activity, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        Log.d("Main", "signInWithCredential:onComplete:" + task.isSuccessful());

                        if (!task.isSuccessful()) {
                            Log.w("MainAcitivyt", "signInWithCredential", task.getException());
                            Toast.makeText(activity, "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();
                        }
                        else{
                           // This line has been changed.
                           activity.startActivity(AccountCreationActivity.newIntent(activity));
                        }
                    }
                });
    }

【讨论】：