分离对Activity和GoogleApiClient的关注

Question

像往常一样,我的代码中有很多代码,我LoginActivity真的更愿意将Activity责任与Google Play注册分开.

在LoginActivity多次重写此代码之后,在许多不同的应用程序中,简单(而不是那么优雅)的解决方案是将Google API客户端创建为Application类对象.但是,由于连接状态会影响用户体验流程,因此我从未对这种方法感到高兴.

有一种优雅的方式放置在GoogleApiClient外面Activity吗？

Answer 1

0. TL; DR

对于不耐烦的编码器,可以在GitHub上找到以下实现的工作版本.

将我们的问题仅减少到连接概念,我们可以考虑:

1. 它有有限的状态.
2. 它封装了连接客户端.
3. 它(相当)是独一无二的.
4. 当前状态会影响应用程序的行为.

1.国家格局

这是一种行为模式,允许对象在其内部状态发生变化时改变其行为.在GoF的设计模式一书描述了一个TCP连接可以通过这种模式来表示(这也是我们的情况下).

来自状态机的状态应该是a singleton,并且在Java中最简单的方法是创建Enum命名State如下:

public enum State {
    CREATED {
        void connect(Connection connection) {
            connection.onSignUp();
        }
    },
    OPENING {
        void connect(Connection connection) {
            connection.onSignIn();
        }
    },
    OPENED {
        void disconnect(Connection connection) {
            connection.onSignOut();
        }
        void revoke(Connection connection) {
            connection.onRevokeAndSignOut();
        }
    },
    CLOSED {
        void connect(Connection connection) {
            connection.onSignIn();
        }
    };

    void connect(Connection connection) {}
    void disconnect(Connection connection) {}
    void revoke(Connection connection) {}
}

在Activity将与通信Connection抽象类通过方法(其保持的上下文中)connect(),disconnect()和revoke().当前状态定义了这些方法的行为方式:

public void connect() {
    currentState.connect(this);
}

public void disconnect() {
    currentState.disconnect(this);
}

public void revoke() {
    currentState.revoke(this);
}

private void changeState(State state) {
    currentState = state;
    setChanged();
    notifyObservers(state);
}

2.代理模式

该类GoogleConnection继承Connection并封装GoogleApiClient,因此它必须提供两者ConnectionCallbacks,OnConnectionFailedListener如下所示:

@Override
public void onConnected(Bundle connectionHint) {
    changeState(State.OPENED);
}

@Override
public void onConnectionSuspended(int cause) {
    mGoogleApiClient.connect();
}

@Override
public void onConnectionFailed(ConnectionResult result) {
    if (state.equals(State.CLOSED) && result.hasResolution()) {
        changeState(State.CREATED);
        connectionResult = result;
    } else {
        connect();
    }
}

public void onActivityResult(int resultCode) {
    if (resultCode == Activity.RESULT_OK) {
        connect();
    } else {
        changeState(State.CREATED);
    }
}

的方法onSignIn(),onSignUp(),onSignOut(),和onRevokeAndSignOut需要对这种解释第二步.

public void onSignUp() {
    try {
        Activity activity = activityWeakReference.get();
        changeState(State.OPENING);
        connectionResult.startResolutionForResult(activity, REQUEST_CODE);
    } catch (IntentSender.SendIntentException e) {
        changeState(State.CREATED);
        mGoogleApiClient.connect();
    }
}

public void onSignIn() {
    if (!mGoogleApiClient.isConnected() && !mGoogleApiClient.isConnecting()) {
        mGoogleApiClient.connect();
    }
}

public void onSignOut() {
    Plus.AccountApi.clearDefaultAccount(mGoogleApiClient);
    mGoogleApiClient.disconnect();
    changeState(State.CLOSED);
    mGoogleApiClient.connect();
}

public void onRevokeAndSignOut() {
    Plus.AccountApi.clearDefaultAccount(mGoogleApiClient);
    Plus.AccountApi.revokeAccessAndDisconnect(mGoogleApiClient);
    changeState(State.CLOSED);
    mGoogleApiClient = mGoogleApiClientBuilder.build();
    mGoogleApiClient.connect();
}

3.单身模式

由于不需要重复重新创建此类,因此我们将其作为单例提供:

public static Connection getInstance(Activity activity) {
    if (null == sConnection) {
        sConnection = new GoogleConnection(activity);
    }

    return sConnection;
}

public void onActivityResult(int result) {
    if (result == Activity.RESULT_OK) {
        changeState(State.CREATED);
    } else {
        changeState(State.CLOSED);
    }
    onSignIn();
}

private GoogleConnection(Activity activity) {
    activityWeakReference = new WeakReference<>(activity);

    googleApiClientBuilder = new GoogleApiClient
           .Builder(activity)
           .addConnectionCallbacks(this)
           .addOnConnectionFailedListener(this)
           .addApi(Plus.API, Plus.PlusOptions.builder().build())
           .addScope(new Scope("email"));

    googleApiClient = googleApiClientBuilder.build();
    currentState = State.CLOSED;

    googleApiClient.connect();
}

4.可观察的模式

该Connection班扩展了Java Observable,那么一个或多个活动,可以观察状态的变化:

@Override
protected void onCreate(Bundle bundle) {
    mConnection = GoogleConnection.getInstance(this);
    mConnection.addObserver(this);
}

@Override
protected void onDestroy() {
    mConnection.deleteObserver(this);
}

@Override
protected void onActivityResult(int request, int result, Intent data) {
    if (Connection.REQUEST_CODE == request) {
        mConnection.onActivityResult(result);
    }
}

@Override
public void update(Observable observable, Object data) {
    if (observable == mGoogleConnection) {
        // UI/UX magic happens here ;-)
    }
}