1: 第一种是纯的在代码中设置
2:第二种是设置一个背景的图片，然后将图片设置为背景
mainactivity：
public class MainActivity extends AppCompatActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);}public void alertDialogShowUsingStyle(View view) {AlertDialog alertDialog = new AlertDialog.Builder(this,R.style.DialogStyle).create();alertDialog.show();//alert dialog 必须要show 以后设置这个布局，不然不起作用alertDialog.setContentView(R.layout.layout_dialog);Window window = alertDialog.getWindow();window.setGravity(Gravity.BOTTOM);window.getDecorView().setPadding(0,0,0,0);window.setLayout(WindowManager.LayoutParams.MATCH_PARENT, WindowManager.LayoutParams.WRAP_CONTENT);}public void dialogShowUsingStyle(View view) {Dialog dialog &