在android中，画布Canvas的高宽其实是屏幕的高宽。 

1.

WindowManager windowManager = getWindowManager();   Display display = windowManager.getDefaultDisplay();   screenWidth = display.getWidth();   screenHeight = display.getHeight();  

2

DisplayMetrics dm = new DisplayMetrics();  this.getWindowManager().getDefaultDisplay().getMetrics(dm);//this指当前activity  screenWidth =dm.widthPixels;  screenHeight =dm.heightPixels;  

以上两种方法在屏幕未显示的时候，还是处于0的状态，即要在setContentView调用之后才有效。 

还可以在onDraw中由canvas来获得

viewWidth=this.getWidth();   viewHeight=this.getHeight();  

2.重写view的onSizeChanged，该方法会在onCreate之后，onDraw之前调用 

protected void onSizeChanged(int w, int h, int oldw, int oldh) {   
viewHeight=h;   
viewWidth=w;   
super.onSizeChanged(w, h, oldw, oldh);   
}  

还有对屏幕显示的一些设置： 

requestWindowFeature(Window.FEATURE_NO_TITLE);  

//设置为全屏模式getWindow().setFlags

1. setRequesteOrientation(ActivityInfo.SCREEN_ORIENTATION_LADSCAPE);