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);

}

}