系统语言改变时，输入法变成默认输入法分析

当系统的语言改变时，选择的输入法会变成默认输入法：
实现的过程在：InputMethodManagerService.java中的：
mContext.registerReceiver(// 这里对语言改变广播的监听。
                new BroadcastReceiver() {
                    @Override
                    public void onReceive(Context context, Intent intent) {
                        synchronized(mMethodMap) {
                            checkCurrentLocaleChangedLocked();//当接收到语言改变发送的广播时执行方法
                        }
                    }
                }, filter);
        
在checkCurrentLocaleChangedLocked()方法中：
有个updateFromSettingsLocked()方法
updateFromSettingsLocked()这个方法：
   void updateFromSettingsLocked() {
        // We are assuming that whoever is changing DEFAULT_INPUT_METHOD and
        // ENABLED_INPUT_METHODS is taking care of keeping them correctly in
        // sync, so we will never have a DEFAULT_INPUT_METHOD that is not
        // enabled.
        String id = Settings.Secure.getString(mContext.getContentResolver(),
                Settings.Secure.DEFAULT_INPUT_METHOD);//获取默认输入法
        // There is no input method selected, try to choose new applicable input method.
        if (TextUtils.isEmpty(id) && chooseNewDefaultIMELocked()) {
            id = Settings.Secure.getString(mContext.getContentResolver(),
                    Settings.Secure.DEFAULT_INPUT_METHOD);
        }
        if (!TextUtils.isEmpty(id)) {
            try {
                setInputMethodLocked(id, getSelectedInputMethodSubtypeId(id));//设置当前输入法为默认输入法。
            } catch (IllegalArgumentException e) {
                Slog.w(TAG, "Unknown input method from prefs: " + id, e);
                mCurMethodId = null;
                unbindCurrentMethodLocked(true);
            }
            mShortcutInputMethodsAndSubtypes.clear();
        } else {
            // There is no longer an input method set, so stop any current one.
            mCurMethodId = null;
            unbindCurrentMethodLocked(true);
        }
    }