//Activity 代码设置透明
protected void onCreate(Bundle savedInstanceState) {
    getWindow().requestFeature(Window.FEATURE_NO_TITLE);
    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        Window window = getWindow();
        window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS | WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
        window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
        window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
        window.setStatusBarColor(Color.TRANSPARENT);
        window.setNavigationBarColor(Color.TRANSPARENT);
    }else if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT){
        // 透明状态栏
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
        // 透明导航栏
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
        //带有actionbar或者标题栏的话要在布局文件里加入android:fitsSystemWindows="true"
        //Theme <item name="android:fitsSystemWindows">true</item>
    }
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}