android - 多次调用 OnResume/OnPause

Question

我的 MainActivity 正在加载不同的 fragment 。此外，可以从 MainActivity 打开 Settings-Activity。

如果用户只是在 fragment 之间切换，一切都很好。

当打开 Settings-Activity 并返回 MainActivity 时，onResume 和 onPause 被调用两次。如果用户打开 Settings-Activity 并再次返回 MainActivity，onResume 和 onPause 将被调用 3 次。每次用户打开 Settings-Activity 并返回 MainActivity 时，这个值都会增加。

主 Activity

 public class MainActivity extends AppCompatActivity implements MyFragment.OnListFragmentInteractionListener, AsyncResponse {


                    private FragmentA fragmentA = new FragmentA();

                    private DatabaseHandler databaseHandler = new DatabaseHandler(this);

                    private NavigationView navigationView;
                    private DrawerLayout drawer;
                    private Toolbar toolbar;

                    // index to identify current nav menu item
                    private static int navItemIndex = 0;

                    public static String CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;

                    // toolbar titles respected to selected nav menu item
                    private String[] activityTitles;

                    // flag to load home fragment when user presses back key
                    private Handler mHandler;

                    @Override
                    protected void onCreate(Bundle savedInstanceState) {

                        super.onCreate(savedInstanceState);

                        setContentView(R.layout.activity_main);

                        fragmentA.setDatabaseHandler(this.databaseHandler);

                        // Init UI
                        toolbar = (Toolbar) findViewById(R.id.toolbar);
                        setSupportActionBar(toolbar);

                        mHandler = new Handler();

                        drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
                        navigationView = (NavigationView) findViewById(R.id.nav_view);

                        fabSendButton = (FloatingActionButton) findViewById(R.id.fab);

                        // Navigation view header
                        navHeader = navigationView.getHeaderView(0);


                        // load toolbar titles from string resources
                        activityTitles = getResources().getStringArray(R.array.sliding_menu_item_activity_titles);


                        // initializing navigation menu
                        setUpNavigationView();

                        if (savedInstanceState == null) {
                            navItemIndex = 0;
                            CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;
                            loadHomeFragment();
                        }
                    }

                    /***
                     * Returns respected fragment that user
                     * selected from navigation menu
                     */
                    private void loadHomeFragment() {

                        // set toolbar title
                        setToolbarTitle();

                        // if user select the current navigation menu again, don't do anything
                        // just close the navigation drawer
                        if (getSupportFragmentManager().findFragmentByTag(CURRENT_TAG) != null) {
                            drawer.closeDrawers();
                            return;
                        }

                        // Sometimes, when fragment has huge data, screen seems hanging
                        // when switching between navigation menus
                        // So using runnable, the fragment is loaded with cross fade effect
                        // This effect can be seen in GMail app
                        Runnable mPendingRunnable = new Runnable() {
                            @Override
                            public void run() {
                                // update the activity_main_header_with_item content by replacing fragments
                                Fragment fragment = getFragment();
                                FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
                                fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
                                fragmentTransaction.replace(R.id.frame, fragment, CURRENT_TAG);
                                fragmentTransaction.commit();
                            }
                        };

                        // If mPendingRunnable is not null, then add to the message queue
                        if (mPendingRunnable != null) {
                            mHandler.post(mPendingRunnable);
                        }

                        //Closing drawer on item click
                        drawer.closeDrawers();

                        // refresh toolbar menu
                        invalidateOptionsMenu();
                    }

                    private Fragment getFragment() {
                        switch (navItemIndex) {
                            case 0:
                                return this.fragmentA;
                            case 1:
                                Fragment B fragmentB = new FragmentB();
                                fragmentB.setDatabaseHandler(this.databaseHandler);
                                return fragmentB;
                            default:
                                return this.fragmentA;
                        }
                    }

                    private void setToolbarTitle() {
                        getSupportActionBar().setTitle(activityTitles[navItemIndex]);
                    }

                    private void setUpNavigationView() {
                        //Setting Navigation View Item Selected Listener to handle the item click of the navigation menu
                        navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {

                            // This method will trigger on item Click of navigation menu
                            @Override
                            public boolean onNavigationItemSelected(MenuItem menuItem) {

                                //Check to see which item was being clicked and perform appropriate action
                                switch (menuItem.getItemId()) {
                                    //Replacing the activity_main_header_with_item content with ContentFragment Which is our Inbox View;
                                    case R.id.nav_A:
                                        navItemIndex = 0;
                                        CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;
                                        break;
                                    case R.id.nav_B:
                                        navItemIndex = 1;
                                        CURRENT_TAG = MyConstants.TAG_FRAGMENT_B;
                                        break;
                                    default:
                                        navItemIndex = 0;
                                }

                                loadHomeFragment();

                                return true;
                            }
                        });

                        ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.openDrawer, R.string.closeDrawer) {

                            @Override
                            public void onDrawerClosed(View drawerView) {
                                // Code here will be triggered once the drawer closes as we dont want anything to happen so we leave this blank
                                super.onDrawerClosed(drawerView);
                            }

                            @Override
                            public void onDrawerOpened(View drawerView) {
                                // Code here will be triggered once the drawer open as we dont want anything to happen so we leave this blank
                                super.onDrawerOpened(drawerView);
                            }
                        };

                        //Setting the actionbarToggle to drawer layout
                        drawer.setDrawerListener(actionBarDrawerToggle);

                        //calling sync state is necessary or else your hamburger icon wont show up
                        actionBarDrawerToggle.syncState();
                    }

                    @Override
                    public boolean onCreateOptionsMenu(Menu menu) {
                        getMenuInflater().inflate(R.menu.activity_main_header_with_item, menu);
                        return true;
                    }

             @Override
                public boolean onCreateOptionsMenu(Menu menu) {
                    getMenuInflater().inflate(R.menu.activity_main_header_with_item, menu);
                    // Disable Player Icon in case no player is found on device
                    Intent intent = Intent.makeMainSelectorActivity(Intent.ACTION_MAIN, ScrobblOrDroidConstants.MUSIC_APP);
                    List<ResolveInfo> activities = getPackageManager().queryIntentActivities(intent, 0);
                    if(activities == null || activities.size() <= 0) {
                        MenuItem player = menu.findItem(R.id.player);
                        if(player != null){
                            player.setVisible(false);
                        }
                    }
                    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();

                    //noinspection SimplifiableIfStatement
                    if (id == R.id.player) {
                        Timber.i( "Added onClick listener to ImageView ivPlayer.");
                        Intent intent = Intent.makeMainSelectorActivity(Intent.ACTION_MAIN, ScrobblOrDroidConstants.MUSIC_APP);
                        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                        startActivity(intent);
                        return true;
                      } else if (id == R.id.settings) {
                        // launch settings activity
                        startActivity(new Intent(MainActivity.this, SettingsActivity.class));
                        return true;
                    }
                    return super.onOptionsItemSelected(item);
                }

            @Override
            public void onResume() {
                Timber.i("MainActivity.onResume-called.");
                activityVisible = true;
                updateHomeFragment();
                callLongUserOperation();
                super.onResume();
            }

            @Override
            public void onPause() {
                Timber.i("MainActivity.onPause-called.");
                activityVisible = false;
                super.onPause();
            }
         }

  public void updateHomeFragment() {
        if (CURRENT_TAG == MyConstants.TAG_HOME) {
            Timber.i( "updating HomeFragment");
            fragmentA.swap();
        }
    }

设置 Activity

public class SettingsActivity extends AppCompatPreferenceActivity implements SharedPreferences.OnSharedPreferenceChangeListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setupActionBar();
        getFragmentManager().beginTransaction().replace(android.R.id.content, new MainPreferenceFragment()).commit();
    }

    private void setupActionBar() {
        ViewGroup rootView = (ViewGroup)findViewById(R.id.action_bar_root);
        View view = getLayoutInflater().inflate(R.layout.pref_toolbar, rootView, false);
        rootView.addView(view, 0);
        Toolbar toolbar = (Toolbar)findViewById(R.id.pref_toolbar);
        setSupportActionBar(toolbar);
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            // Show the Up button in the action bar.
            actionBar.setDisplayHomeAsUpEnabled(true);
        }
    }

    public static class MainPreferenceFragment extends PreferenceFragment {
        @Override
        public void onCreate(final Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.pref_main);

            // gallery EditText change listener
            bindPreferenceSummaryToValue(findPreference(MyConstants.RECENTLY_SCROBBLED_KEY));

            bindPreferenceSummaryToValue(findPreference(MyConstants.SCROBBLE_DURATION_KEY));

            // feedback preference click listener
            Preference myPref = findPreference("key_send_feedback");
            myPref.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
                public boolean onPreferenceClick(Preference preference) {
                    sendFeedback(getActivity());
                    return true;
                }
            });

            // rating preference click listener
            Preference myPrefRate = findPreference("key_send_rate");
            myPrefRate.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
                public boolean onPreferenceClick(Preference preference) {
                    sendRating(getActivity());
                    return true;
                }
            });
        }
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            onBackPressed();
        }
        return super.onOptionsItemSelected(item);
    }

    private static void bindPreferenceSummaryToValue(Preference preference) {
        preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);
        sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
                PreferenceManager.getDefaultSharedPreferences(preference.getContext()).getString(preference.getKey(), ""));
    }

    /**
     * A preference value change listener that updates the preference's summary
     * to reflect its new value.
     */
    private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() {
        @Override
        public boolean onPreferenceChange(Preference preference, Object newValue) {
            String stringValue = newValue.toString();

            if(preference.getKey().equalsIgnoreCase(MyConstants.RECENTLY_SCROBBLED_KEY)){
                preference.setSummary(stringValue + " " + preference.getContext().getResources().getString(R.string.pref_recently_scrobbled_summary));
            }
            if(preference.getKey().equalsIgnoreCase(MyConstants.SCROBBLE_DURATION_KEY)){
                preference.setSummary(preference.getContext().getResources().getString(R.string.pref_scrobble_percentage_summary, stringValue));
            }
            return true;
        }
    };

    /**
     * Email client intent to send support mail
     * Appends the necessary device information to email body
     * useful when providing support
     */
    public static void sendFeedback(Context context) {
        String body = null;
        try {
            body = context.getPackageManager().getPackageInfo(context.getPackageName(), 0).versionName;
            body = "\n\n-----------------------------\nPlease don't remove this information\n Device OS: Android \n Device OS version: " +
                    Build.VERSION.RELEASE + "\n App Version: " + body + "\n Device Brand: " + Build.BRAND +
                    "\n Device Model: " + Build.MODEL + "\n Device Manufacturer: " + Build.MANUFACTURER;
        } catch (PackageManager.NameNotFoundException e) {
        }
        Intent intent = new Intent(Intent.ACTION_SEND);
        intent.setType("message/rfc822");
        intent.putExtra(Intent.EXTRA_EMAIL, new String[]{MyConstants.E_MAIL_ADDRESS});
        intent.putExtra(Intent.EXTRA_SUBJECT, "Feedback for " + context.getResources().getString(R.string.app_name));
        intent.putExtra(Intent.EXTRA_TEXT, body);
        context.startActivity(Intent.createChooser(intent, context.getString(R.string.pref_choose_email_client)));
    }

    public static void sendRating(Context context) {
        Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse(MyConstants.PLAY_STORE_URL));
        context.startActivity(i);;
    }

    @Override
    public void onResume() {
        super.onResume();
        PreferenceManager.getDefaultSharedPreferences(getApplicationContext()).registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onPause() {
        PreferenceManager.getDefaultSharedPreferences(getApplicationContext()).registerOnSharedPreferenceChangeListener(this);
        super.onPause();
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        if(key.equalsIgnoreCase(MyConstants.NOTIFICATION_ENABLED_KEY)){
            EventBus.getDefault().post(new NotificationEvent());
            Timber.i( "NotificationEvent Posted");
        }
    }
}

AppCompatPreferenceActivity

 public class AppCompatPreferenceActivity extends PreferenceActivity {

        private AppCompatDelegate mDelegate;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            getDelegate().installViewFactory();
            getDelegate().onCreate(savedInstanceState);
            super.onCreate(savedInstanceState);
        }

        @Override
        protected void onPostCreate(Bundle savedInstanceState) {
            super.onPostCreate(savedInstanceState);
            getDelegate().onPostCreate(savedInstanceState);
        }

        public ActionBar getSupportActionBar() {
            return getDelegate().getSupportActionBar();
        }

        public void setSupportActionBar(@Nullable Toolbar toolbar) {
            getDelegate().setSupportActionBar(toolbar);
        }

        @Override
        public MenuInflater getMenuInflater() {
            return getDelegate().getMenuInflater();
        }

        @Override
        public void setContentView(@LayoutRes int layoutResID) {
            getDelegate().setContentView(layoutResID);
        }

        @Override
        public void setContentView(View view) {
            getDelegate().setContentView(view);
        }

        @Override
        public void setContentView(View view, ViewGroup.LayoutParams params) {
            getDelegate().setContentView(view, params);
        }

        @Override
        public void addContentView(View view, ViewGroup.LayoutParams params) {
            getDelegate().addContentView(view, params);
        }

        @Override
        protected void onPostResume() {
            super.onPostResume();
            getDelegate().onPostResume();
        }

        @Override
        protected void onTitleChanged(CharSequence title, int color) {
            super.onTitleChanged(title, color);
            getDelegate().setTitle(title);
        }

        @Override
        public void onConfigurationChanged(Configuration newConfig) {
            super.onConfigurationChanged(newConfig);
            getDelegate().onConfigurationChanged(newConfig);
        }

        @Override
        protected void onStop() {
            super.onStop();
            getDelegate().onStop();
        }

        @Override
        protected void onDestroy() {
            super.onDestroy();
            getDelegate().onDestroy();
        }

        public void invalidateOptionsMenu() {
            getDelegate().invalidateOptionsMenu();
        }

        private AppCompatDelegate getDelegate() {
            if (mDelegate == null) {
                mDelegate = AppCompatDelegate.create(this, null);
            }
            return mDelegate;
        }
    }

AndroidManifest.xml

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

    <uses-sdk
        android:minSdkVersion="15"
        android:targetSdkVersion="25" />

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">
        <activity
            android:name=".ui.activity.MainActivity"
            android:label="@string/app_name"
            android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".ui.activity.LoginActivity"
            android:excludeFromRecents="true"
            android:label="@string/app_name"
            android:screenOrientation="portrait"></activity>
        <activity
            android:name=".ui.activity.SettingsActivity"
            android:label="@string/settings">
            <!-- Parent activity meta-data to support 4.0 and lower -->
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".ui.activity.MainActivity" />
        </activity>

        <!-- start service on device boot complete -->
        <receiver
            android:name=".util.receiver.MyBroadcastReceiver"
            android:enabled="true"
            android:exported="true"
            android:label="StartMyServiceAtBootReceiver">
            <intent-filter>
                <action android:name="com.android.music.metachanged" />
                <action android:name="com.android.music.playstatechanged" />
                <!-- <action android:name="android.intent.action._BOOT_COMPLETED" /> -->
            </intent-filter>
        </receiver>
        <receiver android:name=".util.receiver.MyInternetConnectionBroadcastReceiver">
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            </intent-filter>
        </receiver>

    </application>

</manifest>

如何避免这些多次调用？

Answer 1

这似乎是 Android SDK 构建工具中的错误。更新后它就像一个魅力!