Android 4.x的一个变通方案:

我找到了AutoResizeTextView，它在我的Android 2.1模拟器上工作得很好。我非常喜欢它。但不幸的是，它在我自己的4.0.4手机和4.1模拟器上失败了。经过尝试，我发现它可以通过在xml中的AutoResizeTextView类中添加以下属性轻松解决:

android：ellipsize=“none” android：singleLine=“true”

有了上面的两行，现在AutoResizeTextView在我的2.1和4.1模拟器和我自己的4.0.4手机上完美地工作。

希望这对你有所帮助。: -)

我为此写了一篇博客。

我根据Kirill Grouchnikov关于在新的android market应用中使用的自定义组件的博客文章创建了一个名为ResizableButton的组件。我把src代码放在这里。

另一方面，mosabua读了我的文章，并告诉我他将开源他的实现，这比我的更快。我希望他能尽快发布:)

我只是借用了一些其他人的想法，并在下面写了一些代码，可能会有帮助。

import android.content.Context;
import android.graphics.Canvas;
import android.text.Layout.Alignment;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.TextView;

public class AutoResizeTextView extends TextView {
    private static final int MAX_SIZE = 1000;

    private static final int MIN_SIZE = 5;

    private TextPaint mTextPaint;

    private float mSpacingMult = 1.0f;

    private float mSpacingAdd = 0.0f;

    private boolean needAdapt = false;

    private boolean adapting = false;

    public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    public AutoResizeTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public AutoResizeTextView(Context context) {
        super(context);
        init();
    }

    private void init() {
        mTextPaint = new TextPaint();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (adapting) {
            return;
        }
        if (needAdapt) {
            adaptTextSize();
        } else {
            super.onDraw(canvas);
        }
    }

    private void adaptTextSize() {
        CharSequence text = getText();
        int viewWidth = getMeasuredWidth();
        int viewHeight = getMeasuredHeight();

        if (viewWidth==0 || viewHeight==0
                || TextUtils.isEmpty(text)) {
            return;
        }

        adapting = true;
        /* binary search */
        int bottom=MIN_SIZE, top=MAX_SIZE, mid = 0;
        while (bottom <= top) {
            mid = (bottom + top)/2;
            mTextPaint.setTextSize(mid);
            int textWidth = (int) mTextPaint.measureText(text, 0, text.length());
            int textHeight = getTextHeight(text, viewWidth);
            if (textWidth<viewWidth && textHeight<viewHeight) {
                bottom = mid+1;
            } else {
                top = mid-1;
            }
        }

        int newSize = mid-1;
        setTextSize(TypedValue.COMPLEX_UNIT_PX, newSize);

        adapting=false;
        needAdapt = false;

        invalidate();
    }

    private int getTextHeight(CharSequence text, int targetWidth) {
        StaticLayout layout = new StaticLayout(text, mTextPaint, targetWidth,
                Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
        return layout.getHeight();
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        needAdapt = true;
    }

    @Override
    protected void onTextChanged(CharSequence text, int start,
            int lengthBefore, int lengthAfter) {
        super.onTextChanged(text, start, lengthBefore, lengthAfter);
        needAdapt = true;
    }

    @Override
    public void setLineSpacing(float add, float mult) {
        super.setLineSpacing(add, mult);
        mSpacingMult = mult;
        mSpacingAdd = add;
    }
}

从2018年6月起，Android正式开始支持Android 4.0 (API级别14)及更高版本的此功能。 查看它在:Autosizing TextViews

Android 8.0 (API级别26)及更高版本:

<?xml version="1.0" encoding="utf-8"?>
<TextView
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:autoSizeTextType="uniform"
    android:autoSizeMinTextSize="12sp"
    android:autoSizeMaxTextSize="100sp"
    android:autoSizeStepGranularity="2sp" />

编程:

setAutoSizeTextTypeUniformWithConfiguration(int autoSizeMinTextSize, int autoSizeMaxTextSize, 
        int autoSizeStepGranularity, int unit)

textView.setAutoSizeTextTypeUniformWithConfiguration(
                1, 17, 1, TypedValue.COMPLEX_UNIT_DIP);

Android 8.0之前的Android版本(API级别26):

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

  <TextView
      android:layout_width="match_parent"
      android:layout_height="200dp"
      app:autoSizeTextType="uniform"
      app:autoSizeMinTextSize="12sp"
      app:autoSizeMaxTextSize="100sp"
      app:autoSizeStepGranularity="2sp" />

</LinearLayout>

编程:

TextViewCompat.setAutoSizeTextTypeUniformWithConfiguration(
TextView textView, int autoSizeMinTextSize, int autoSizeMaxTextSize, int autoSizeStepGranularity, int unit) 

TextViewCompat.setAutoSizeTextTypeUniformWithConfiguration(textView, 1, 17, 1,
TypedValue.COMPLEX_UNIT_DIP);

注意:TextView必须有layout_width="match_parent"或绝对大小!

扩展TextView和覆盖onDraw与下面的代码。它将保持文本纵横比，但将其大小填充空间。如果需要，您可以轻松地修改代码以进行拉伸。

  @Override
  protected void onDraw(@NonNull Canvas canvas) {
    TextPaint textPaint = getPaint();
    textPaint.setColor(getCurrentTextColor());
    textPaint.setTextAlign(Paint.Align.CENTER);
    textPaint.drawableState = getDrawableState();

    String text = getText().toString();
    float desiredWidth = getMeasuredWidth() - getPaddingLeft() - getPaddingRight() - 2;
    float desiredHeight = getMeasuredHeight() - getPaddingTop() - getPaddingBottom() - 2;
    float textSize = textPaint.getTextSize();

    for (int i = 0; i < 10; i++) {
      textPaint.getTextBounds(text, 0, text.length(), rect);
      float width = rect.width();
      float height = rect.height();

      float deltaWidth = width - desiredWidth;
      float deltaHeight = height - desiredHeight;

      boolean fitsWidth = deltaWidth <= 0;
      boolean fitsHeight = deltaHeight <= 0;

      if ((fitsWidth && Math.abs(deltaHeight) < 1.0)
          || (fitsHeight && Math.abs(deltaWidth) < 1.0)) {
        // close enough
        break;
      }

      float adjustX = desiredWidth / width;
      float adjustY = desiredHeight / height;

      textSize = textSize * (adjustY < adjustX ? adjustY : adjustX);

      // adjust text size
      textPaint.setTextSize(textSize);
    }
    float x = desiredWidth / 2f;
    float y = desiredHeight / 2f - rect.top - rect.height() / 2f;
    canvas.drawText(text, x, y, textPaint);
  }

我需要调整文本的大小，以完美地适应视图边界。Chase的解决方案只是减小文本大小，如果有足够的空间，这个方案也会扩大文本。

为了使所有的快速和精确，我使用了平分方法而不是迭代while，正如你可以在resizeText()方法中看到的那样。这就是为什么你也有一个MAX_TEXT_SIZE选项。我还附上了onoelle的建议。

Android 4.4测试

/**
 *               DO WHAT YOU WANT TO PUBLIC LICENSE
 *                    Version 2, December 2004
 *
 * Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
 *
 * Everyone is permitted to copy and distribute verbatim or modified
 * copies of this license document, and changing it is allowed as long
 * as the name is changed.
 *
 *            DO WHAT YOU WANT TO PUBLIC LICENSE
 *   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
 *
 *  0. You just DO WHAT YOU WANT TO.
 */

import android.content.Context;
import android.text.Layout.Alignment;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.TextView;

/**
 * Text view that auto adjusts text size to fit within the view.
 * If the text size equals the minimum text size and still does not
 * fit, append with an ellipsis.
 *
 * @author Chase Colburn
 * @since Apr 4, 2011
 */
public class AutoResizeTextView extends TextView {

    // Minimum text size for this text view
    public static final float MIN_TEXT_SIZE = 26;

    // Maximum text size for this text view
    public static final float MAX_TEXT_SIZE = 128;

    private static final int BISECTION_LOOP_WATCH_DOG = 30;

    // Interface for resize notifications
    public interface OnTextResizeListener {
        public void onTextResize(TextView textView, float oldSize, float newSize);
    }

    // Our ellipse string
    private static final String mEllipsis = "...";

    // Registered resize listener
    private OnTextResizeListener mTextResizeListener;

    // Flag for text and/or size changes to force a resize
    private boolean mNeedsResize = false;

    // Text size that is set from code. This acts as a starting point for resizing
    private float mTextSize;

    // Temporary upper bounds on the starting text size
    private float mMaxTextSize = MAX_TEXT_SIZE;

    // Lower bounds for text size
    private float mMinTextSize = MIN_TEXT_SIZE;

    // Text view line spacing multiplier
    private float mSpacingMult = 1.0f;

    // Text view additional line spacing
    private float mSpacingAdd = 0.0f;

    // Add ellipsis to text that overflows at the smallest text size
    private boolean mAddEllipsis = true;

    // Default constructor override
    public AutoResizeTextView(Context context) {
        this(context, null);
    }

    // Default constructor when inflating from XML file
    public AutoResizeTextView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    // Default constructor override
    public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mTextSize = getTextSize();
    }

    /**
     * When text changes, set the force resize flag to true and reset the text size.
     */
    @Override
    protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) {
        mNeedsResize = true;
        // Since this view may be reused, it is good to reset the text size
        resetTextSize();
    }

    /**
     * If the text view size changed, set the force resize flag to true
     */
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        if (w != oldw || h != oldh) {
            mNeedsResize = true;
        }
    }

    /**
     * Register listener to receive resize notifications
     * @param listener
     */
    public void setOnResizeListener(OnTextResizeListener listener) {
        mTextResizeListener = listener;
    }

    /**
     * Override the set text size to update our internal reference values
     */
    @Override
    public void setTextSize(float size) {
        super.setTextSize(size);
        mTextSize = getTextSize();
    }

    /**
     * Override the set text size to update our internal reference values
     */
    @Override
    public void setTextSize(int unit, float size) {
        super.setTextSize(unit, size);
        mTextSize = getTextSize();
    }

    /**
     * Override the set line spacing to update our internal reference values
     */
    @Override
    public void setLineSpacing(float add, float mult) {
        super.setLineSpacing(add, mult);
        mSpacingMult = mult;
        mSpacingAdd = add;
    }

    /**
     * Set the upper text size limit and invalidate the view
     * @param maxTextSize
     */
    public void setMaxTextSize(float maxTextSize) {
        mMaxTextSize = maxTextSize;
        requestLayout();
        invalidate();
    }

    /**
     * Return upper text size limit
     * @return
     */
    public float getMaxTextSize() {
        return mMaxTextSize;
    }

    /**
     * Set the lower text size limit and invalidate the view
     * @param minTextSize
     */
    public void setMinTextSize(float minTextSize) {
        mMinTextSize = minTextSize;
        requestLayout();
        invalidate();
    }

    /**
     * Return lower text size limit
     * @return
     */
    public float getMinTextSize() {
        return mMinTextSize;
    }

    /**
     * Set flag to add ellipsis to text that overflows at the smallest text size
     * @param addEllipsis
     */
    public void setAddEllipsis(boolean addEllipsis) {
        mAddEllipsis = addEllipsis;
    }

    /**
     * Return flag to add ellipsis to text that overflows at the smallest text size
     * @return
     */
    public boolean getAddEllipsis() {
        return mAddEllipsis;
    }

    /**
     * Reset the text to the original size
     */
    public void resetTextSize() {
        if(mTextSize > 0) {
            super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
            //mMaxTextSize = mTextSize;
        }
    }

    /**
     * Resize text after measuring
     */
    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        if(changed || mNeedsResize) {
            int widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight();
            int heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop();
            resizeText(widthLimit, heightLimit);
        }
        super.onLayout(changed, left, top, right, bottom);
    }


    /**
     * Resize the text size with default width and height
     */
    public void resizeText() {
        int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop();
        int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight();
        resizeText(widthLimit, heightLimit);
    }

    /**
     * Resize the text size with specified width and height
     * @param width
     * @param height
     */
    public void resizeText(int width, int height) {
        CharSequence text = getText();
        // Do not resize if the view does not have dimensions or there is no text
        if(text == null || text.length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) {
            return;
        }

        // Get the text view's paint object
        TextPaint textPaint = getPaint();

        // Store the current text size
        float oldTextSize = textPaint.getTextSize();

        // Bisection method: fast & precise
        float lower = mMinTextSize;
        float upper = mMaxTextSize;
        int loop_counter=1;
        float targetTextSize = (lower+upper)/2;
        int textHeight = getTextHeight(text, textPaint, width, targetTextSize);
        while(loop_counter < BISECTION_LOOP_WATCH_DOG && upper - lower > 1) {
            targetTextSize = (lower+upper)/2;
            textHeight = getTextHeight(text, textPaint, width, targetTextSize);
            if(textHeight > height)
                upper = targetTextSize;
            else
                lower = targetTextSize;
            loop_counter++;
        }

        targetTextSize = lower;
        textHeight = getTextHeight(text, textPaint, width, targetTextSize);

        // If we had reached our minimum text size and still don't fit, append an ellipsis
        if(mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) {
            // Draw using a static layout
            // modified: use a copy of TextPaint for measuring
            TextPaint paintCopy = new TextPaint(textPaint);
            paintCopy.setTextSize(targetTextSize);
            StaticLayout layout = new StaticLayout(text, paintCopy, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false);
            // Check that we have a least one line of rendered text
            if(layout.getLineCount() > 0) {
                // Since the line at the specific vertical position would be cut off,
                // we must trim up to the previous line
                int lastLine = layout.getLineForVertical(height) - 1;
                // If the text would not even fit on a single line, clear it
                if(lastLine < 0) {
                    setText("");
                }
                // Otherwise, trim to the previous line and add an ellipsis
                else {
                    int start = layout.getLineStart(lastLine);
                    int end = layout.getLineEnd(lastLine);
                    float lineWidth = layout.getLineWidth(lastLine);
                    float ellipseWidth = paintCopy.measureText(mEllipsis);

                    // Trim characters off until we have enough room to draw the ellipsis
                    while(width < lineWidth + ellipseWidth) {
                        lineWidth = paintCopy.measureText(text.subSequence(start, --end + 1).toString());
                    }
                    setText(text.subSequence(0, end) + mEllipsis);
                }
            }
        }

        // Some devices try to auto adjust line spacing, so force default line spacing
        // and invalidate the layout as a side effect
        setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize);
        setLineSpacing(mSpacingAdd, mSpacingMult);

        // Notify the listener if registered
        if(mTextResizeListener != null) {
            mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize);
        }

        // Reset force resize flag
        mNeedsResize = false;
    }

    // Set the text size of the text paint object and use a static layout to render text off screen before measuring
    private int getTextHeight(CharSequence source, TextPaint originalPaint, int width, float textSize) {
        // modified: make a copy of the original TextPaint object for measuring
        // (apparently the object gets modified while measuring, see also the
        // docs for TextView.getPaint() (which states to access it read-only)
        TextPaint paint = new TextPaint(originalPaint);
        // Update the text paint object
        paint.setTextSize(textSize);
        // Measure using a static layout
        StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
        return layout.getHeight();
    }

}