if(VERSION.SDK_INT >= VERSION_CODES.KITKAT) {    //4.4以上
                                //透明状态栏
                                getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
                                //透明导航栏
                                getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
                        } 
原文:http://my.oschina.net/u/1273583/blog/469537