android.preference.PreferenceScreen#findPreference ( )源码实例Demo

private void updateLoopCountPrefs() {
  String loopCount =
      Integer.toString(SwitchAccessPreferenceUtils.getNumberOfScanningLoops(getActivity()));

  PreferenceScreen autoScanScreen =
      (PreferenceScreen) findPreference(R.string.pref_category_auto_scan_key);
  EditTextPreference autoScanLoopCountPreference =
      (EditTextPreference)
          autoScanScreen.findPreference(
              getString(R.string.pref_key_point_scan_and_autoscan_loop_count));
  updatePreferenceValue(autoScanLoopCountPreference, loopCount);

  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
    PreferenceScreen pointScanScreen =
        (PreferenceScreen) findPreference(R.string.pref_category_point_scan_key);
    EditTextPreference pointScanLoopCountPreference =
        (EditTextPreference)
            pointScanScreen.findPreference(
                getString(R.string.pref_key_point_scan_and_autoscan_loop_count));
    updatePreferenceValue(pointScanLoopCountPreference, loopCount);
  }
}
 

private void resetList() {
    getPreferenceScreen().removeAll();
    addPreferencesFromResource(R.xml.usb_device_preferences);

    PreferenceScreen preferenceScreen = getPreferenceScreen();
    Preference header = preferenceScreen.findPreference(PREF_OBJECT_NAME);
    header.setTitle(mUsbInfo.getName());
    header.setOnPreferenceClickListener(this);

    for (int i = 0; i < mSites.size(); ++i) {
        Website site = mSites.get(i);
        Preference preference = new WebsitePreference(getActivity(), site, mCategory);
        preference.getExtras().putSerializable(SingleWebsitePreferences.EXTRA_SITE, site);
        preference.setFragment(SingleWebsitePreferences.class.getCanonicalName());
        preferenceScreen.addPreference(preference);
    }

    // Force this list to be reloaded if the activity is resumed.
    mSites = null;
}
 

private void updateStartScanDelayPrefs() {
  String startScanDelaySeconds =
      Float.toString(SwitchAccessPreferenceUtils.getFirstItemScanDelaySeconds(getActivity()));

  PreferenceScreen autoScanScreen =
      (PreferenceScreen) findPreference(R.string.pref_category_auto_scan_key);
  EditTextPreference autoScanStartDelayPreference =
      (EditTextPreference)
          autoScanScreen.findPreference(getString(R.string.pref_key_start_scan_delay));
  updatePreferenceValue(autoScanStartDelayPreference, startScanDelaySeconds);

  if (VERSION.SDK_INT >= VERSION_CODES.N) {
    PreferenceScreen pointScanScreen =
        (PreferenceScreen) findPreference(R.string.pref_category_point_scan_key);
    EditTextPreference pointScanStartDelayPreference =
        (EditTextPreference)
            pointScanScreen.findPreference(getString(R.string.pref_key_start_scan_delay));
    updatePreferenceValue(pointScanStartDelayPreference, startScanDelaySeconds);
  }
}
 

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    addPreferencesFromResource(R.xml.pref_main);

    PreferenceScreen screen = getPreferenceScreen();
    AppSignatureHelper signatureHelper = new AppSignatureHelper(getActivity());

    ArrayList<String> appSignatures = signatureHelper.getAppSignatures();
    Preference pref = screen.findPreference("app_signature");
    if (!appSignatures.isEmpty() && pref != null) {
        pref.setSummary(appSignatures.get(0));
    }
}
 

private static CheckBoxPreference[] findDecodePrefs(PreferenceScreen preferences, String... keys) {
  CheckBoxPreference[] prefs = new CheckBoxPreference[keys.length];
  for (int i = 0; i < keys.length; i++) {
    prefs[i] = (CheckBoxPreference) preferences.findPreference(keys[i]);
  }
  return prefs;
}
 

@Override
public boolean onPreferenceClick(Preference preference) {
    Bundle extras = preference.peekExtras();
    if (extras != null) {
        UsbInfo usbInfo = (UsbInfo) extras.getSerializable(EXTRA_USB_INFO);
        if (usbInfo != null) {
            usbInfo.revoke();

            PreferenceScreen preferenceScreen = getPreferenceScreen();
            preferenceScreen.removePreference(preference);
            mUsbPermissionCount--;
            if (!hasPermissionsPreferences()) {
                Preference heading = preferenceScreen.findPreference(PREF_PERMISSIONS);
                preferenceScreen.removePreference(heading);
            }
            return true;
        }
    }

    // Handle the Clear & Reset preference click by showing a confirmation.
    new AlertDialog.Builder(getActivity(), R.style.AlertDialogTheme)
            .setTitle(R.string.website_reset)
            .setMessage(R.string.website_reset_confirmation)
            .setPositiveButton(R.string.website_reset, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    resetSite();
                }
            })
            .setNegativeButton(R.string.cancel, null)
            .show();
    return true;
}
 

private boolean hasPermissionsPreferences() {
    if (mUsbPermissionCount > 0) return true;
    PreferenceScreen screen = getPreferenceScreen();
    for (String key : PERMISSION_PREFERENCE_KEYS) {
        if (screen.findPreference(key) != null) return true;
    }
    return false;
}
 

private static void configureAboutPreferences(Context context, PreferenceScreen screen) {
    String version = "Unknown";
    try {
        PackageInfo info = context.getPackageManager().getPackageInfo(context.getPackageName(), 0);
        version = info.versionName;
    } catch (PackageManager.NameNotFoundException e) {
        e.printStackTrace();
    }
    Preference versionPreference = screen.findPreference(VERSION_KEY);
    versionPreference.setSummary(version);
}
 

private static CheckBoxPreference[] findDecodePrefs(PreferenceScreen preferences, String... keys) {
  CheckBoxPreference[] prefs = new CheckBoxPreference[keys.length];
  for (int i = 0; i < keys.length; i++) {
    prefs[i] = (CheckBoxPreference) preferences.findPreference(keys[i]);
  }
  return prefs;
}
 

private void addMonitorApp(String pkg) {
    if (TextUtils.isEmpty(pkg)) {
        return;
    }

    PreferenceManager manager = getPreferenceManager();
    try {
        PreferenceScreen screen = (PreferenceScreen) RefUtil.callDeclaredMethod(manager,
                "inflateFromResource",
                new Class[]{Context.class, int.class, PreferenceScreen.class},
                getActivity(), R.xml.prefs_monitor_apps, null);
        screen.setKey(pkg);
        screen.setTitle(pkg);
        screen.setSummary(getMonitorAppSummary(pkg, null));

        PreferenceGroup appConfigPref = (PreferenceGroup) screen.findPreference("monitor_app_config_pref");
        appConfigPref.setTitle(pkg);

        Preference titleViewIdPref = appConfigPref.findPreference("title_view_id_pref");
        titleViewIdPref.setKey(GlobalConfig.getSharedPrefKeyForTitleId(pkg));
        titleViewIdPref.getExtras().putString(KEY_PREF_EXTRA, pkg);
        titleViewIdPref.setOnPreferenceChangeListener(mOnPreferenceChangeListener);

        Preference contentViewIdPref = appConfigPref.findPreference("content_view_id_pref");
        contentViewIdPref.setKey(GlobalConfig.getSharedPrefKeyForContentId(pkg));
        contentViewIdPref.getExtras().putString(KEY_PREF_EXTRA, pkg);
        contentViewIdPref.setOnPreferenceChangeListener(mOnPreferenceChangeListener);

        PreferenceCategory container = (PreferenceCategory)
                getPreferenceManager().findPreference("monitor_apps_pref");
        container.addPreference(screen);
    } catch (Exception e) {
        LogWriter.e(TAG, "Add monitor ppp to preference error!", e);
    }
}
 

@Override
public void setStringFieldSummary(String fieldName) {
    PreferenceScreen pfs = getPreferenceScreen();
    SharedPreferences sp = pfs.getSharedPreferences();
    Preference pref = pfs.findPreference(fieldName);

    String val = sp.getString(fieldName, null);
    if (TextUtils.isEmpty(val)) {
        val = getDefaultFieldSummary(fieldName);
    }
    setPreferenceSummary(pref, val);
}
 

/**
 * Set summary of a list field If empty will display default summary If one
 * item selected will display item name
 * 
 * @param fieldName the preference key name
 */
public void setListFieldSummary(String fieldName) {
    PreferenceScreen pfs = getPreferenceScreen();
    ListPreference pref = (ListPreference) pfs.findPreference(fieldName);
    if (pref == null) {
        Log.w(THIS_FILE, "Unable to find preference " + fieldName);
        return;
    }

    CharSequence val = pref.getEntry();
    if (TextUtils.isEmpty(val)) {
        val = getDefaultFieldSummary(fieldName);
    }
    setPreferenceSummary(pref, val);
}
 

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setTitle(getString(R.string.pref_category_notifications));
    addPreferencesFromResource(R.xml.pref_notify);

    PreferenceScreen screen = getPreferenceScreen();

    // Link pref_notify_foreground and pref_notify_success_lock
    final CheckBoxPreference foreground = (CheckBoxPreference)
            screen.findPreference("pref_notify_foreground");
    final CheckBoxPreference success = (CheckBoxPreference)
            screen.findPreference("pref_notify_success");
    final CheckBoxPreference success_lock = (CheckBoxPreference)
            screen.findPreference("pref_notify_success_lock");
    foreground.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
        @Override
        public boolean onPreferenceChange(Preference preference, Object newValue) {
            success.setEnabled(!((Boolean) newValue));
            success_lock.setEnabled(!((Boolean) newValue));
            return true;
        }
    });
    foreground
            .getOnPreferenceChangeListener()
            .onPreferenceChange(foreground, foreground.isChecked());
}
 

private static CheckBoxPreference[] findDecodePrefs(PreferenceScreen preferences, String... keys) {
  CheckBoxPreference[] prefs = new CheckBoxPreference[keys.length];
  for (int i = 0; i < keys.length; i++) {
    prefs[i] = (CheckBoxPreference) preferences.findPreference(keys[i]);
  }
  return prefs;
}
 

private static CheckBoxPreference[] findDecodePrefs(PreferenceScreen preferences, String... keys) {
  CheckBoxPreference[] prefs = new CheckBoxPreference[keys.length];
  for (int i = 0; i < keys.length; i++) {
    prefs[i] = (CheckBoxPreference) preferences.findPreference(keys[i]);
  }
  return prefs;
}
 

/**
 * Resets the current site, clearing all permissions and storage used (inc. cookies).
 */
@VisibleForTesting
protected void resetSite() {
    if (getActivity() == null) return;
    // Clear the screen.
    // TODO(mvanouwerkerk): Refactor this class so that it does not depend on the screen state
    // for its logic. This class should maintain its own data model, and only update the screen
    // after a change is made.
    PreferenceScreen screen = getPreferenceScreen();
    for (String key : PERMISSION_PREFERENCE_KEYS) {
        Preference preference = screen.findPreference(key);
        if (preference != null) screen.removePreference(preference);
    }

    String origin = mSite.getAddress().getOrigin();
    WebsitePreferenceBridge.nativeClearCookieData(origin);
    WebsitePreferenceBridge.nativeClearBannerData(origin);

    // Clear the permissions.
    mSite.setAutoplayPermission(ContentSetting.DEFAULT);
    mSite.setBackgroundSyncPermission(ContentSetting.DEFAULT);
    mSite.setCameraPermission(ContentSetting.DEFAULT);
    mSite.setCookiePermission(ContentSetting.DEFAULT);
    mSite.setGeolocationPermission(ContentSetting.DEFAULT);
    mSite.setJavaScriptPermission(ContentSetting.DEFAULT);
    mSite.setMicrophonePermission(ContentSetting.DEFAULT);
    mSite.setMidiPermission(ContentSetting.DEFAULT);
    mSite.setNotificationPermission(ContentSetting.DEFAULT);
    mSite.setPopupPermission(ContentSetting.DEFAULT);
    mSite.setProtectedMediaIdentifierPermission(ContentSetting.DEFAULT);
    mSite.setSubresourceFilterPermission(ContentSetting.DEFAULT);

    for (UsbInfo info : mSite.getUsbInfo()) info.revoke();

    // Clear the storage and finish the activity if necessary.
    if (mSite.getTotalUsage() > 0) {
        clearStoredData();
    } else {
        // Clearing stored data implies popping back to parent menu if there
        // is nothing left to show. Therefore, we only need to explicitly
        // close the activity if there's no stored data to begin with.
        getActivity().finish();
    }
}
 

static void removePreference(final String prefKey, final PreferenceScreen screen) {
    final Preference preference = screen.findPreference(prefKey);
    if (preference != null) {
        screen.removePreference(preference);
    }
}
 

private static void configureOrbotPreferences(PreferenceScreen screen) {
    Preference useOrbotPreference = screen.findPreference(USE_TOR_KEY);
    useOrbotPreference.setEnabled(OrbotHelper.isOrbotInstalled(screen.getContext()));
}
 

static void removePreference(final String prefKey, final PreferenceScreen screen) {
    final Preference preference = screen.findPreference(prefKey);
    if (preference != null) {
        screen.removePreference(preference);
    }
}
 

static void removePreference(final String prefKey, final PreferenceScreen screen) {
    final Preference preference = screen.findPreference(prefKey);
    if (preference != null) {
        screen.removePreference(preference);
    }
}