android - 即使应用程序在后台，如何启动相同的 Activity ？

Question

我的应用程序中有 3 个 Activity ，登录，A 和 B。登录 Activity 是我的启动器页面。登录后，它重定向到 Activity A。现在单击主页按钮时，它暂停 Activity A 并转到后台，同时单击应用程序图标它重新启动 Activity A。我需要启动登录 Activity ，即使 Activity A 在背景。我怎样才能做到这一点，请帮助？

Answer 1

每当您的应用进入后台时，您都需要完成所有 Activity

HomeWatcher.java

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.util.Log;

public class HomeWatcher {

    static final String TAG = HomeWatcher.class.getSimpleName();
    private Context mContext;
    private IntentFilter mFilter;
    private OnHomePressedListener mListener;
    private InnerRecevier mRecevier;

    public HomeWatcher(Context context) {
        mContext = context;
        mFilter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);
    }

    public void setOnHomePressedListener(OnHomePressedListener listener) {
        mListener = listener;
        mRecevier = new InnerRecevier();
    }

    public void startWatch() {
        if (mRecevier != null) {
            mContext.registerReceiver(mRecevier, mFilter);
        }
    }

    public void stopWatch() {
        if (mRecevier != null) {
            mContext.unregisterReceiver(mRecevier);
        }
    }

    class InnerRecevier extends BroadcastReceiver {
        final String SYSTEM_DIALOG_REASON_KEY = "reason";
        final String SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS = "globalactions";
        final String SYSTEM_DIALOG_REASON_RECENT_APPS = "recentapps";
        final String SYSTEM_DIALOG_REASON_HOME_KEY = "homekey";

        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (action.equals(Intent.ACTION_CLOSE_SYSTEM_DIALOGS)) {
                String reason = intent.getStringExtra(SYSTEM_DIALOG_REASON_KEY);
                if (reason != null) {
                    if (mListener != null) {
                        if (reason.equals(SYSTEM_DIALOG_REASON_HOME_KEY)) {
                            mListener.onHomePressed();
                        } else if (reason.equals(SYSTEM_DIALOG_REASON_RECENT_APPS)) {
                            mListener.onRecentAppPressed();
                        }
                    }
                }
            }
        }
    }
}

MyApplication.java

public class MyApplication extends Application implements Application.ActivityLifecycleCallbacks {

    private static MyApplication mInstance;
    public static String TAG = MyApplication.class.getSimpleName();
    private Activity mActivity;

    @Override
    public void onCreate() {
        super.onCreate();
        mInstance = this;
        registerActivityLifecycleCallbacks(this);

        HomeWatcher mHomeWatcher = new HomeWatcher(this);
        mHomeWatcher.setOnHomePressedListener(new OnHomePressedListener() {
            @Override
            public void onHomePressed() {
                // do other stuff before finish
                Log.d(TAG, "onHomePressed");
                if (mActivity != null)
                    mActivity.finishAffinity();
            }

            @Override
            public void onRecentAppPressed() {
                // do other stuff before finish
                Log.d(TAG, "onRecentAppPressed ");
                if (mActivity != null)
                    mActivity.finishAffinity();
            }
        });
        mHomeWatcher.startWatch();
    }

    @Override
    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
        mActivity = activity;
    }

    @Override
    public void onActivityStarted(Activity activity) {
        mActivity = activity;
    }

    @Override
    public void onActivityResumed(Activity activity) {
        mActivity = activity;
    }

    @Override
    public void onActivityPaused(Activity activity) {

    }

    @Override
    public void onActivityStopped(Activity activity) {

    }

    @Override
    public void onActivitySaveInstanceState(Activity activity, Bundle outState) {

    }

    @Override
    public void onActivityDestroyed(Activity activity) {

    }
}

AndroidManifest.xml

 <application
    android:name="your_package_name.MyApplication">
    ....
 </application>