Android 獲取設備寬高分辨率

想要獲取設備寬高分辨率，最好放到Utils跑龍套里面。

基礎知識：

1. WindowManager

• The interface that apps use to talk to the window manager.

• Use Context.getSystemService(Context.WINDOW_SERVICE) to get one of these.

• Each window manager instance is bound to a particular Display. To obtain a WindowManager for a different display, use createDisplayContext(Display) to obtain a Context for that display, then use Context.getSystemService(Context.WINDOW_SERVICE) to get the WindowManager.

• The simplest way to show a window on another display is to create a Presentation.  The presentation will automatically obtain a WindowManager and Context for that display.

    整個Android的窗口機制是基于一個叫做 WindowManager，這個接口可以添加view到屏幕，也可以從屏幕刪除view。它面向的對象一端是屏幕，另一端就是View，直接忽略我們以前的Activity或者Dialog之類的東東。其實我們的Activity或者Diolog底層的實現也是通過WindowManager，這個 WindowManager是全局的，整個系統就是這個唯一的東東。它是顯示View的最底層了。 (引自http://gundumw100.iteye.com/blog/830235)

方法：

2.Display

Provides information about the size and density of a logical display.

The display area is described in two different ways.

• The application display area specifies the part of the display that may contain an application window, excluding the system decorations.  The application display area may be smaller than the real display area because the system subtracts the space needed for decor elements such as the status bar.  Use the following methods to query the application display area: getSize(Point), getRectSize(Rect) and getMetrics(DisplayMetrics).

• The real display area specifies the part of the display that contains content including the system decorations.  Even so, the real display area may be smaller than the physical size of the display if the window manager is emulating a smaller display using (adb shell am display-size).  Use the following methods to query the real display area: getRealSize(Point), getRealMetrics(DisplayMetrics).

A logical display does not necessarily represent a particular physical display device such as the built-in screen or an external monitor.  The contents of a logical display may be presented on one or more physical displays according to the devices that are currently attached and whether mirroring has been enabled.

下面給出代碼：

import android.content.Context;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.WindowManager;

public class Utils {

	public static int getScreenWidth(Context context) {
		WindowManager manager = (WindowManager) context
				.getSystemService(Context.WINDOW_SERVICE);
		Display display = manager.getDefaultDisplay();
		return display.getWidth();
	}

	public static int getScreenHeight(Context context) {
		WindowManager manager = (WindowManager) context
				.getSystemService(Context.WINDOW_SERVICE);
		Display display = manager.getDefaultDisplay();
		return display.getHeight();
	}

	public static float getScreenDensity(Context context) {
		try {
			DisplayMetrics dm = new DisplayMetrics();
			WindowManager manager = (WindowManager) context
					.getSystemService(Context.WINDOW_SERVICE);
			manager.getDefaultDisplay().getMetrics(dm);
			return dm.density;
		} catch (Exception ex) {

		}
		return 1.0f;
	}

}