获取屏幕宽高

　　　　//获取屏幕分辨率
        WindowManager dm = this.getWindowManager();
        DisplayMetrics outMetrics = new DisplayMetrics();
        dm.getDefaultDisplay().getMetrics(outMetrics);
        int screenWidth = outMetrics.widthPixels;
        int screenHeight = outMetrics.heightPixels;
        //设置控件参数
        LinearLayout.LayoutParams layoutParams = (LayoutParams) btn.getLayoutParams();
        layoutParams.width = screenWidth / 2;
        btn.setLayoutParams(layoutParams);