对于kotlin用户

fun Activity.displayMetrics(): DisplayMetrics {
   val displayMetrics = DisplayMetrics()
   windowManager.defaultDisplay.getMetrics(displayMetrics)
   return displayMetrics
}

在Activity中，你可以使用它

     resources.displayMetrics.let { displayMetrics ->
        val height = displayMetrics.heightPixels
        val width = displayMetrics.widthPixels
    }

或者碎片化

    activity?.displayMetrics()?.run {
        val height = heightPixels
        val width = widthPixels
    }

DisplayMetrics dimension = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dimension);
        int width = dimension.widthPixels;
        int height = dimension.heightPixels;

这里没有一个答案适用于Chrome OS的多显示器，或即将到来的可折叠设备。

在查找当前配置时，始终使用getResources(). getconfiguration()中当前活动的配置。不要使用来自后台活动或系统资源的配置。后台活动没有大小，系统的配置可能包含多个大小和方向冲突的窗口，因此无法提取可用的数据。

所以答案是

val config = context.getResources().getConfiguration()
val (screenWidthPx, screenHeightPx) = config.screenWidthDp.dp to config.screenHeightDp.dp

•Kotlin版本通过扩展属性

如果你想知道屏幕的像素大小以及dp，使用这些扩展属性真的很有帮助:

DimensionUtils.kt

import android.content.Context
import android.content.res.Resources
import android.graphics.Rect
import android.graphics.RectF
import android.os.Build
import android.util.DisplayMetrics
import android.view.WindowManager
import kotlin.math.roundToInt

/**
 * @author aminography
 */

private val displayMetrics: DisplayMetrics by lazy { Resources.getSystem().displayMetrics }

/**
 * Returns boundary of the screen in pixels (px).
 */
val screenRectPx: Rect
    get() = displayMetrics.run { Rect(0, 0, widthPixels, heightPixels) }

/**
 * Returns boundary of the screen in density independent pixels (dp).
 */
val screenRectDp: RectF
    get() = screenRectPx.run { RectF(0f, 0f, right.px2dp, bottom.px2dp) }

/**
 * Returns boundary of the physical screen including system decor elements (if any) like navigation
 * bar in pixels (px).
 */
val Context.physicalScreenRectPx: Rect
    get() = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
        (applicationContext.getSystemService(Context.WINDOW_SERVICE) as WindowManager)
            .run { DisplayMetrics().also { defaultDisplay.getRealMetrics(it) } }
            .run { Rect(0, 0, widthPixels, heightPixels) }
    } else screenRectPx

/**
 * Returns boundary of the physical screen including system decor elements (if any) like navigation
 * bar in density independent pixels (dp).
 */
val Context.physicalScreenRectDp: RectF
    get() = physicalScreenRectPx.run { RectF(0f, 0f, right.px2dp, bottom.px2dp) }

/**
 * Converts any given number from pixels (px) into density independent pixels (dp).
 */
val Number.px2dp: Float
    get() = this.toFloat() / displayMetrics.density

/**
 * Converts any given number from density independent pixels (dp) into pixels (px).
 */
val Number.dp2px: Int
    get() = (this.toFloat() * displayMetrics.density).roundToInt()

用法:

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val widthPx = screenRectPx.width()
        val heightPx = screenRectPx.height()
        println("[PX] screen width: $widthPx , height: $heightPx")

        val widthDp = screenRectDp.width()
        val heightDp = screenRectDp.height()
        println("[DP] screen width: $widthDp , height: $heightDp")

        println()
        
        val physicalWidthPx = physicalScreenRectPx.width()
        val physicalHeightPx = physicalScreenRectPx.height()
        println("[PX] physical screen width: $physicalWidthPx , height: $physicalHeightPx")

        val physicalWidthDp = physicalScreenRectDp.width()
        val physicalHeightDp = physicalScreenRectDp.height()
        println("[DP] physical screen width: $physicalWidthDp , height: $physicalHeightDp")
    }
}

结果:

当设备处于纵向方向时:

[PX] screen width: 1440 , height: 2392
[DP] screen width: 360.0 , height: 598.0

[PX] physical screen width: 1440 , height: 2560
[DP] physical screen width: 360.0 , height: 640.0

当设备处于横向时:

[PX] screen width: 2392 , height: 1440
[DP] screen width: 598.0 , height: 360.0

[PX] physical screen width: 2560 , height: 1440
[DP] physical screen width: 640.0 , height: 360.0

完整的方法是使用“getRealSize”来返回真实的分辨率(包括当用户改变分辨率时)。

我注意到所有其他可用的函数，包括文档中说要用的代替this的函数，在某些情况下结果会更小。

下面是代码:

            WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
            Point size = new Point();
            wm.getDefaultDisplay().getRealSize(size);
            final int width = size.x, height = size.y;

因为这可以在不同的方向上改变，这里有一个解决方案(在Kotlin中)，无论朝向如何，都能得到正确的结果:

/**
 * returns the natural orientation of the device: Configuration.ORIENTATION_LANDSCAPE or Configuration.ORIENTATION_PORTRAIT .<br></br>
 * The result should be consistent no matter the orientation of the device
 */
@JvmStatic
fun getScreenNaturalOrientation(context: Context): Int {
    //based on : http://stackoverflow.com/a/9888357/878126
    val windowManager = context.getSystemService(Context.WINDOW_SERVICE) as WindowManager
    val config = context.resources.configuration
    val rotation = windowManager.defaultDisplay.rotation
    return if ((rotation == Surface.ROTATION_0 || rotation == Surface.ROTATION_180) && config.orientation == Configuration.ORIENTATION_LANDSCAPE || (rotation == Surface.ROTATION_90 || rotation == Surface.ROTATION_270) && config.orientation == Configuration.ORIENTATION_PORTRAIT)
        Configuration.ORIENTATION_LANDSCAPE
    else
        Configuration.ORIENTATION_PORTRAIT
}

/**
 * returns the natural screen size (in pixels). The result should be consistent no matter the orientation of the device
 */
@JvmStatic
fun getScreenNaturalSize(context: Context): Point {
    val screenNaturalOrientation = getScreenNaturalOrientation(context)
    val wm = context.getSystemService(Context.WINDOW_SERVICE) as WindowManager
    val point = Point()
    wm.defaultDisplay.getRealSize(point)
    val currentOrientation = context.resources.configuration.orientation
    if (currentOrientation == screenNaturalOrientation)
        return point
    else return Point(point.y, point.x)
}

使用这段代码，你可以得到运行时显示的宽度和高度:

DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
int height = displayMetrics.heightPixels;
int width = displayMetrics.widthPixels;

在视图中，你需要这样做:

((Activity) getContext()).getWindowManager()
                         .getDefaultDisplay()
                         .getMetrics(displayMetrics);

在某些情况下，设备有一个导航栏，你必须在运行时检查:

public boolean showNavigationBar(Resources resources)
{
    int id = resources.getIdentifier("config_showNavigationBar", "bool", "android");
    return id > 0 && resources.getBoolean(id);
}

如果设备有一个导航栏，那么计算它的高度:

private int getNavigationBarHeight() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
        DisplayMetrics metrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(metrics);
        int usableHeight = metrics.heightPixels;
        getWindowManager().getDefaultDisplay().getRealMetrics(metrics);
        int realHeight = metrics.heightPixels;
        if (realHeight > usableHeight)
            return realHeight - usableHeight;
        else
            return 0;
    }
    return 0;
}

所以设备的最终高度是:

int height = displayMetrics.heightPixels + getNavigationBarHeight();