Android获取屏幕宽高

一、前言

android 4.4（sdk 19）之后，获取屏幕高度需要考虑底部导航栏等decor。网上很多方案是没有考虑这一点的，因此获取到的屏幕高度小于实际高度，误导开发者。

二、错误方案

列举几种常见的获取出来高度可能小于实际高度的方案：

DisplayMetrics dm = getApplicationContext().getResources().getDisplayMetrics(); int screenWidth = dm.widthPixels; int screenHeight = dm.heightPixels;

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

WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);int screenWidth = wm.getDefaultDisplay().getWidth();int screenHeight = wm.getDefaultDisplay().getHeight();

DisplayMetrics outMetrics = new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(outMetrics);int screenWidth = outMetrics.widthPixels;int screenHeight = outMetrics.heightPixels;

三、正确方案

以下是供参考的获取完整高度的方案：

WindowManager windowManager = (WindowManager) getApplication().getSystemService(Context.WINDOW_SERVICE);Display display = windowManager.getDefaultDisplay();Point outPoint = new Point();if (Build.VERSION.SDK_INT >= 19) {// 可能有虚拟按键的情况display.getRealSize(outPoint);} else {// 不可能有虚拟按键display.getSize(outPoint);}int mRealSizeWidth;//手机屏幕真实宽度int mRealSizeHeight;//手机屏幕真实高度mRealSizeHeight = outPoint.y;mRealSizeWidth = outPoint.x;

DisplayMetrics metric = new DisplayMetrics();getWindowManager().getDefaultDisplay().getRealMetrics(metric);int width = metric.widthPixels; // 宽度（PX）int height = metric.heightPixels; // 高度（PX）

四、源码解读

以上方法的区别在于"getRealSize"和"getRealMetrics"，查看源码：

1.getMetrics：

    /**     * Gets display metrics that describe the size and density of this display.     * The size returned by this method does not necessarily represent the     * actual raw size (native resolution) of the display.     *      * 1. The returned size may be adjusted to exclude certain system decor elements     * that are always visible.     * 
     * 2. It may be scaled to provide compatibility with older applications that     * were originally designed for smaller displays.     * 
     * 3. It can be different depending on the WindowManager to which the display belongs.     * 
     * - If requested from non-Activity context (e.g. Application context via     * {@code (WindowManager) getApplicationContext().getSystemService(Context.WINDOW_SERVICE)})     * metrics will report the size of the entire display based on current rotation and with     * subtracted system decoration areas.     * 
     * - If requested from activity (either using {@code getWindowManager()} or     * {@code (WindowManager) getSystemService(Context.WINDOW_SERVICE)}) resulting metrics will     * correspond to current app window metrics. In this case the size can be smaller than physical     * size in multi-window mode.     * 
     *     * @param outMetrics A {@link DisplayMetrics} object to receive the metrics.     */    public void getMetrics(DisplayMetrics outMetrics) {        synchronized (this) {            updateDisplayInfoLocked();            mDisplayInfo.getAppMetrics(outMetrics, getDisplayAdjustments());        }    }

包含decor时，返回的size可能不准确
老式机型下可能不准确
可能因WindowManager而改变

2.getRealSize：

    /**     * Gets the real size of the display without subtracting any window decor or     * applying any compatibility scale factors.     *      * The size is adjusted based on the current rotation of the display.     * 
     * The real size may be smaller than the physical size of the screen when the     * window manager is emulating a smaller display (using adb shell wm size).     * 
     *     * @param outSize Set to the real size of the display.     */    public void getRealSize(Point outSize) {        synchronized (this) {            updateDisplayInfoLocked();            outSize.x = mDisplayInfo.logicalWidth;            outSize.y = mDisplayInfo.logicalHeight;        }    }

获取的size没有减去任何decor或者考虑缩放因素
使用"adb shell wm size"可以查看设备的物理尺寸

3.getRealMetrics：

    /**     * Gets display metrics based on the real size of this display.     *      * The size is adjusted based on the current rotation of the display.     * 
     * The real size may be smaller than the physical size of the screen when the     * window manager is emulating a smaller display (using adb shell wm size).     * 
     *     * @param outMetrics A {@link DisplayMetrics} object to receive the metrics.     */    public void getRealMetrics(DisplayMetrics outMetrics) {        synchronized (this) {            updateDisplayInfoLocked();            mDisplayInfo.getLogicalMetrics(outMetrics,                    CompatibilityInfo.DEFAULT_COMPATIBILITY_INFO, null);        }    }

基于getRealSize实现

五、参考文献

Android 获取屏幕高和宽（不包含/包含虚拟按键），状态栏的高度
Android获取真正准确的分辨率，拒绝那些瞎扯乱混的文章

一、前言

二、错误方案

三、正确方案

四、源码解读

五、参考文献

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Android获取屏幕宽高

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一、前言

二、错误方案

三、正确方案

四、源码解读

五、参考文献