Android:自定义Dialog大小,显示圆角

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        AlertDialog dialog = builder.create();
        int screenWidth_px = PX_DP_utils.getScreenWidth_PX(this);
        int screenHeight_px = PX_DP_utils.getScreenheight_PX(this);
        dialog.show();
//需要设置属性,否则dialog的大小不起作用!必须先show再set属性
        WindowManager.LayoutParams params = dialog.getWindow().getAttributes();
        params.width = (int) (screenWidth_px * 0.7 + 0.5f);
        params.height = (int) (0.6 * screenHeight_px + 0.5f);
        // 必须使用这个方法,不能使用dialog.setView()的方法
        dialog.getWindow().setContentView(R.layout.dialog_picpick_three);
        //设置dialog的背景颜色为透明色,就可以显示圆角了!!
        dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        dialog.getWindow().setAttributes(params);