在活动的onCreate中，有时需要知道布局可用空间的精确尺寸。经过一番思考，我想出了这种方法。

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        startActivityForResult(new Intent(this, Measure.class), 1);
        // Return without setting the layout, that will be done in onActivityResult.
    }

    @Override
    protected void onActivityResult (int requestCode, int resultCode, Intent data) {
        // Probably can never happen, but just in case.
        if (resultCode == RESULT_CANCELED) {
            finish();
            return;
        }
        int width = data.getIntExtra("Width", -1);
        // Width is now set to the precise available width, and a layout can now be created.            ...
    }
}

public final class Measure extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
       // Create a LinearLayout with a MeasureFrameLayout in it.
        // Just putting a subclass of LinearLayout in works fine, but to future proof things, I do it this way.
        LinearLayout linearLayout = new LinearLayout(this);
        LinearLayout.LayoutParams matchParent = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);
        MeasureFrameLayout measureFrameLayout = new MeasureFrameLayout(this);
        measureFrameLayout.setLayoutParams(matchParent);
        linearLayout.addView(measureFrameLayout);
        this.addContentView(linearLayout, matchParent);
        // measureFrameLayout will now request this second activity to finish, sending back the width.
    }

    class MeasureFrameLayout extends FrameLayout {
        boolean finished = false;
        public MeasureFrameLayout(Context context) {
            super(context);
        }

        @SuppressLint("DrawAllocation")
        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            if (finished) {
                return;
            }
            finished = true;
            // Send the width back as the result.
            Intent data = new Intent().putExtra("Width", MeasureSpec.getSize(widthMeasureSpec));
            Measure.this.setResult(Activity.RESULT_OK, data);
            // Tell this activity to finish, so the result is passed back.
            Measure.this.finish();
        }
    }
}

如果出于某种原因，您不想将另一个活动添加到Android清单中，可以这样做：

public class MainActivity extends Activity {
    static Activity measuringActivity;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        Bundle extras = getIntent().getExtras();
        if (extras == null) {
            extras = new Bundle();
        }
        int width = extras.getInt("Width", -2);
        if (width == -2) {
            // First time in, just start another copy of this activity.
            extras.putInt("Width", -1);
            startActivityForResult(new Intent(this, MainActivity.class).putExtras(extras), 1);
            // Return without setting the layout, that will be done in onActivityResult.
            return;
        }
        if (width == -1) {
            // Second time in, here is where the measurement takes place.
            // Create a LinearLayout with a MeasureFrameLayout in it.
            // Just putting a subclass of LinearLayout in works fine, but to future proof things, I do it this way.
            LinearLayout linearLayout = new LinearLayout(measuringActivity = this);
            LinearLayout.LayoutParams matchParent = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
            MeasureFrameLayout measureFrameLayout = new MeasureFrameLayout(this);
            measureFrameLayout.setLayoutParams(matchParent);
            linearLayout.addView(measureFrameLayout);
            this.addContentView(linearLayout, matchParent);
            // measureFrameLayout will now request this second activity to finish, sending back the width.
        }
    }

    @Override
    protected void onActivityResult (int requestCode, int resultCode, Intent data) {
        // Probably can never happen, but just in case.
        if (resultCode == RESULT_CANCELED) {
            finish();
            return;
        }
        int width = data.getIntExtra("Width", -3);
        // Width is now set to the precise available width, and a layout can now be created. 
        ...
    }

class MeasureFrameLayout extends FrameLayout {
    boolean finished = false;
    public MeasureFrameLayout(Context context) {
        super(context);
    }

    @SuppressLint("DrawAllocation")
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (finished) {
            return;
        }
        finished = true;
        // Send the width back as the result.
        Intent data = new Intent().putExtra("Width", MeasureSpec.getSize(widthMeasureSpec));
        MainActivity.measuringActivity.setResult(Activity.RESULT_OK, data);
        // Tell the (second) activity to finish.
        MainActivity.measuringActivity.finish();
    }
}    

它可能无法回答您的问题，但如果你需要一个视图的维度，但你的代码在尚未布局时（例如在onCreate（）中）正在执行，你可以使用View.getViewTreeObserver（）.addOnGlobalLayoutListener（）设置一个ViewTreeObserver.OnGlobalLayout侦听器，并将需要该视图的相关代码放入尺寸。布局布局完成后，将调用侦听器的回调。

一种方法是：

Display display = getWindowManager().getDefaultDisplay(); 
int width = display.getWidth();
int height = display.getHeight();

它已被弃用，您应该尝试以下代码。前两行代码提供DisplayMetrics对象。此对象包含高度像素、宽度像素等字段。

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

Api级别30更新

final WindowMetrics metrics = windowManager.getCurrentWindowMetrics();
 // Gets all excluding insets
 final WindowInsets windowInsets = metrics.getWindowInsets();
 Insets insets = windowInsets.getInsetsIgnoringVisibility(WindowInsets.Type.navigationBars()
         | WindowInsets.Type.displayCutout());

 int insetsWidth = insets.right + insets.left;
 int insetsHeight = insets.top + insets.bottom;

 // Legacy size that Display#getSize reports
 final Rect bounds = metrics.getBounds();
 final Size legacySize = new Size(bounds.width() - insetsWidth,
         bounds.height() - insetsHeight);

•Kotlin版本通过扩展属性

在android中有多种实现屏幕尺寸的方法，但我认为最好的解决方案可以独立于Context实例，因此您可以在代码中的任何地方使用它。在这里，我通过kotlin扩展属性提供了一个解决方案，它可以很容易地知道以像素为单位的屏幕大小以及dp：

尺寸Utils.kt

import android.content.res.Resources
import android.graphics.Rect
import android.graphics.RectF
import android.util.DisplayMetrics
import kotlin.math.roundToInt

/**
 * @author aminography
 */

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

val screenRectPx: Rect
    get() = displayMetrics.run { Rect(0, 0, widthPixels, heightPixels) }

val screenRectDp: RectF
    get() = displayMetrics.run { RectF(0f, 0f, widthPixels.px2dp, heightPixels.px2dp) }

val Number.px2dp: Float
    get() = this.toFloat() / displayMetrics.density

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")
    }
}

结果：

当设备处于纵向时：

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

当设备处于横向时：

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

如果您不是kotlin的粉丝，请使用java版本：

import android.content.res.Resources;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.DisplayMetrics;

/**
 * @author aminography
 */
public class DimensionUtils {

    private static DisplayMetrics displayMetrics;

    private static DisplayMetrics getDisplayMetrics() {
        if (displayMetrics == null) {
            displayMetrics = Resources.getSystem().getDisplayMetrics();
        }
        return displayMetrics;
    }

    public static Rect screenRectPx() {
        return new Rect(0, 0, getDisplayMetrics().widthPixels, getDisplayMetrics().heightPixels);
    }

    public static RectF screenRectDp() {
        return new RectF(0f, 0f, px2dp(getDisplayMetrics().widthPixels), px2dp(getDisplayMetrics().heightPixels));
    }

    public static float px2dp(int value) {
        return value / getDisplayMetrics().density;
    }

    public static int dp2px(float value) {
        return (int) (value * getDisplayMetrics().density);
    }
}

科特林

fun getScreenHeight(activity: Activity): Int {
    val metrics = DisplayMetrics()
    activity.windowManager.defaultDisplay.getMetrics(metrics)
    return metrics.heightPixels
}

fun getScreenWidth(activity: Activity): Int {
    val metrics = DisplayMetrics()
    activity.windowManager.defaultDisplay.getMetrics(metrics)
    return metrics.widthPixels
}

简单的功能与较低版本兼容。

/**
 * @return screen size int[width, height]
 *
 * */
public int[] getScreenSize(){
    Point size = new Point();
    WindowManager w = getWindowManager();

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2){
        w.getDefaultDisplay().getSize(size);
        return new int[]{size.x, size.y};
    }else{
        Display d = w.getDefaultDisplay();
        //noinspection deprecation
        return new int[]{d.getWidth(), d.getHeight()};
    }
}

要使用：

int width = getScreenSize()[0];
int height = getScreenSize()[1];