我为此用kotlin编写了两个helper函数

/**
 * Gets the float value defined in dimens
 * Define float value as following
 * Example:
 * <item name="example" format="float" type="dimen">1.0</item>
 */
fun Resources.getFloatDimension(dimensResourceId: Int): Float {
    val outValue = TypedValue()
    this.getValue(dimensResourceId, outValue, true)
    return outValue.float
}

/**
 * Gets the dp value defined in dimens
 * Example:
 * <dimen name="example">12dp</dimen>
 *
 * Will return 12
 */
fun Resources.getDimensionInDp(dimensResourceId: Int): Int {
    return (getDimension(dimensResourceId) / displayMetrics.density).toInt()
}

在我的dimension。xml中

<dimen name="test">48dp</dimen>

在代码中

int valueInPixels = (int) getResources().getDimension(R.dimen.test)

这将返回72，作为文档状态乘以当前手机的密度(在我的情况下是48dp x 1.5)

正如文档所述:

检索特定资源ID的维度。单位转换 是基于与资源相关联的当前显示度量。

所以如果你想要精确的dp值，就像在xml中一样，只需将它与DisplayMetrics密度分开

int dp = (int) (getResources().getDimension(R.dimen.test) / getResources().getDisplayMetrics().density);

Dp现在是48

我为此用kotlin编写了两个helper函数

/**
 * Gets the float value defined in dimens
 * Define float value as following
 * Example:
 * <item name="example" format="float" type="dimen">1.0</item>
 */
fun Resources.getFloatDimension(dimensResourceId: Int): Float {
    val outValue = TypedValue()
    this.getValue(dimensResourceId, outValue, true)
    return outValue.float
}

/**
 * Gets the dp value defined in dimens
 * Example:
 * <dimen name="example">12dp</dimen>
 *
 * Will return 12
 */
fun Resources.getDimensionInDp(dimensResourceId: Int): Int {
    return (getDimension(dimensResourceId) / displayMetrics.density).toInt()
}

Context.getResources().getDimension(int id);

使用Kotlin扩展

您可以添加一个扩展来简化这个过程。它允许你只调用context.dp(r.d emen。tutorial_cross_marginTop)来获取Float值

fun Context.px(@DimenRes dimen: Int): Int = resources.getDimension(dimen).toInt()

fun Context.dp(@DimenRes dimen: Int): Float = px(dimen) / resources.displayMetrics.density

如果你想在没有上下文的情况下处理它，你可以使用Resources.getSystem():

val Int.dp get() = this / Resources.getSystem().displayMetrics.density // Float

val Int.px get() = (this * Resources.getSystem().displayMetrics.density).toInt()

例如，在xhdpi设备上，使用24。Dp得到12.0或12。Px得到24

如果你只是想动态改变字体大小，那么你可以:

textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, resources.getDimension(R.dimen.tutorial_cross_marginTop))

正如@achie的回答，你可以像这样从dimensions .xml中获取dp:

val dpValue = (resources.getDimension(R.dimen.tutorial_cross_marginTop)/ resources.displayMetrics.density).toInt()

或者得到这样的sp

val spValue = (resources.getDimension(R.dimen.font_size)/ resources.displayMetrics.scaledDensity).toInt()

关于Resources.java #{getDimension}

    /**
     * Retrieve a dimensional for a particular resource ID.  Unit 
     * conversions are based on the current {@link DisplayMetrics} associated
     * with the resources.
     * 
     * @param id The desired resource identifier, as generated by the aapt
     *           tool. This integer encodes the package, type, and resource
     *           entry. The value 0 is an invalid identifier.
     * 
     * @return Resource dimension value multiplied by the appropriate 
     * metric.
     * 
     * @throws NotFoundException Throws NotFoundException if the given ID does not exist.
     *
     * @see #getDimensionPixelOffset
     * @see #getDimensionPixelSize
     */

资源维度值乘以相应的值