更新：修改代码以修复一些问题。
首先，让我说您提出了一个很好的问题并且很好地提出了问题（两次！）这是我的解决方案：
onMeasure从表面上看，似乎有很多事情发生，并没有多大意义。既然是这种情况，我们将让它onMeasure按原样运行，最后通过设置我们将接受的新最小宽度来判断View' 的边界。在中，使用 a ，我们将强制使用另一个布局 ( )。从文档（强调添加）：onLayoutmStickyWidthonPreDrawViewTreeObserver.OnPreDrawListenerrequestLayout
boolean onPreDraw ()
即将绘制视图树时调用的回调方法。此时，树中的所有视图都已被测量并给出了一个框架。客户可以使用它来调整他们的滚动范围，甚至在绘制之前请求一个新的布局。
onLayout现在将强制执行新的最小宽度设置，现在可以onMeasure更智能地了解可能的情况。
我已经用你的示例代码对此进行了测试，它似乎工作正常。它将需要更多的测试。可能还有其他方法可以做到这一点，但这是该方法的要点。
自定义视图.java
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewTreeObserver;
public class CustomView extends View
implements ViewTreeObserver.OnPreDrawListener {
private int mStickyWidth = STICKY_WIDTH_UNDEFINED;
public CustomView(Context context) {
super(context);
}
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
logMeasureSpecs(widthMeasureSpec, heightMeasureSpec);
int desiredHeight = 10000; // some value that is too high for the screen
int desiredWidth;
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int width;
int height;
// Height
if (heightMode == MeasureSpec.EXACTLY) {
height = heightSize;
} else if (heightMode == MeasureSpec.AT_MOST) {
height = Math.min(desiredHeight, heightSize);
} else {
height = desiredHeight;
}
// Width
if (mStickyWidth != STICKY_WIDTH_UNDEFINED) {
// This is the second time through layout and we are trying renogitiate a greater
// width (mStickyWidth) without breaking the contract with the View.
desiredWidth = mStickyWidth;
} else if (height > BREAK_HEIGHT) { // a number between onMeasure's two final height requirements
desiredWidth = ARBITRARY_WIDTH_LESSER; // arbitrary number
} else {
desiredWidth = ARBITRARY_WIDTH_GREATER; // arbitrary number
}
if (widthMode == MeasureSpec.EXACTLY) {
width = widthSize;
} else if (widthMode == MeasureSpec.AT_MOST) {
width = Math.min(desiredWidth, widthSize);
} else {
width = desiredWidth;
}
Log.d(TAG, "setMeasuredDimension(" + width + ", " + height + ")");
setMeasuredDimension(width, height);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
int w = right - left;
int h = bottom - top;
super.onLayout(changed, left, top, right, bottom);
// Here we need to determine if the width has been unnecessarily constrained.
// We will try for a re-fit only once. If the sticky width is defined, we have
// already tried to re-fit once, so we are not going to have another go at it since it
// will (probably) have the same result.
if (h <= BREAK_HEIGHT && (w < ARBITRARY_WIDTH_GREATER)
&& (mStickyWidth == STICKY_WIDTH_UNDEFINED)) {
mStickyWidth = ARBITRARY_WIDTH_GREATER;
getViewTreeObserver().addOnPreDrawListener(this);
} else {
mStickyWidth = STICKY_WIDTH_UNDEFINED;
}
Log.d(TAG, ">>>>onLayout: w=" + w + " h=" + h + " mStickyWidth=" + mStickyWidth);
}
@Override
public boolean onPreDraw() {
getViewTreeObserver().removeOnPreDrawListener(this);
if (mStickyWidth == STICKY_WIDTH_UNDEFINED) { // Happy with the selected width.
return true;
}
Log.d(TAG, ">>>>onPreDraw() requesting new layout");
requestLayout();
return false;
}
protected void logMeasureSpecs(int widthMeasureSpec, int heightMeasureSpec) {
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
String measureSpecHeight;
String measureSpecWidth;
if (heightMode == MeasureSpec.EXACTLY) {
measureSpecHeight = "EXACTLY";
} else if (heightMode == MeasureSpec.AT_MOST) {
measureSpecHeight = "AT_MOST";
} else {
measureSpecHeight = "UNSPECIFIED";
}
if (widthMode == MeasureSpec.EXACTLY) {
measureSpecWidth = "EXACTLY";
} else if (widthMode == MeasureSpec.AT_MOST) {
measureSpecWidth = "AT_MOST";
} else {
measureSpecWidth = "UNSPECIFIED";
}
Log.d(TAG, "Width: " + measureSpecWidth + ", " + widthSize + " Height: "
+ measureSpecHeight + ", " + heightSize);
}
private static final String TAG = "CustomView";
private static final int STICKY_WIDTH_UNDEFINED = -1;
private static final int BREAK_HEIGHT = 1950;
private static final int ARBITRARY_WIDTH_LESSER = 200;
private static final int ARBITRARY_WIDTH_GREATER = 800;
}
