方法一：
WindowManager wm = (WindowManager) this
.getSystemService(Context.WINDOW_SERVICE);
int width = wm.getDefaultDisplay().getWidth();
int height = wm.getDefaultDisplay().getHeight();
方法二：
WindowManager wm1 = this.getWindowManager();
int width1 = wm1.getDefaultDisplay().getWidth();
int height1 = wm1.getDefaultDisplay().getHeight();
方法一与方法二获取屏幕宽度的方法类似，只是获取WindowManager 对象时的途径不同。
方法三：
WindowManager manager = this.getWindowManager();
DisplayMetrics outMetrics = new DisplayMetrics();
manager.getDefaultDisplay().getMetrics(outMetrics);
int width2 = outMetrics.widthPixels;
int height2 = outMetrics.heightPixels;
方法四：
Resources resources = this.getResources();
DisplayMetrics dm = resources.getDisplayMetrics();
float density1 = dm.density;
int width3 = dm.widthPixels;
int height3 = dm.heightPixels;
方法三与方法四类似。
原文：http://www.cnblogs.com/newcaoguo/p/6230931.html