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

private void toggleSpeaker(Context context){
    AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
    am.setMode(AudioManager.MODE_IN_CALL);
    am.setSpeakerphoneOn(!am.isSpeakerphoneOn());//取反赋值
}