判断当前android系统的尺寸。用来区分平板和手机，亲测。

<span style="font-family:KaiTi_GB2312;font-size:18px;">private double getScreenSizeOfDevice2() {
DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);

double width = dm.widthPixels / dm.xdpi;
double height = dm.heightPixels / dm.ydpi;
double x = Math.pow(width, 2);
double y = Math.pow(height, 2);
double screenInches = Math.sqrt(x + y);
Log.d("TAG2", "The screenInches " + screenInches);
System.out.println("2" + screenInches);
return screenInches;
}</span>