我的方法是:

public void changeTextSize(int initialSize, TextView tv) {

    DisplayMetrics displayMetrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
    double width = displayMetrics.widthPixels / displayMetrics.xdpi;
    double height = displayMetrics.heightPixels / displayMetrics.ydpi;

    Log.i("LOG", "The width of the tested emulator is: " + width);
    Log.i("LOG", "The height of the tested emulator is: " + height);

    double scale = Math.min(width / 2.25, height / 4.0); //See the logcat >>> width = 2.25 and heigt = 4.0
    tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, (int) (initialSize * scale));

}

例如:

changeTextSize(16, findViewById(R.id.myTextView));
changeTextSize(12, findViewById(R.id.myEditText));

我的实现有点复杂，但附带以下好处:

考虑到可用的宽度和高度 适用于单行和多行标签 使用省略号，以防达到最小字体大小 由于内部文本表示形式已更改，因此将最初设置的文本保存在单独的变量中 确保画布总是只有它需要的大小，而它使用所有可用的父元素高度

/**
 * 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.
 * 
 * Based on the original work from Chase Colburn
 * <http://stackoverflow.com/a/5535672/305532>
 *
 * @author Thomas Keller <me@thomaskeller.biz>
 */
public class AutoResizeTextView extends TextView {

    // in dip
    private static final int MIN_TEXT_SIZE = 20;

    private static final boolean SHRINK_TEXT_SIZE = true;

    private static final char ELLIPSIS = '\u2026';

    private static final float LINE_SPACING_MULTIPLIER_MULTILINE = 0.8f;

    private static final float LINE_SPACING_MULTIPLIER_SINGLELINE = 1f;

    private static final float LINE_SPACING_EXTRA = 0.0f;

    private CharSequence mOriginalText;

    // temporary upper bounds on the starting text size
    private float mMaxTextSize;

    // lower bounds for text size
    private float mMinTextSize;

    // determines whether we're currently in the process of measuring ourselves,
    // so we do not enter onMeasure recursively
    private boolean mInMeasure = false;

    // if the text size should be shrinked or if the text size should be kept
    // constant and only characters should be removed to hit the boundaries
    private boolean mShrinkTextSize;

    public AutoResizeTextView(Context context) {
        this(context, null);
        init(context, null);
    }

    public AutoResizeTextView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
        init(context, attrs);
    }

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

    private void init(Context context, AttributeSet attrs) {
        // the current text size is used as maximum text size we can apply to
        // our widget
        mMaxTextSize = getTextSize();
        if (attrs != null) {
            TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AutoResizeTextView);
            mMinTextSize = a.getFloat(R.styleable.AutoResizeTextView_minFontSize, MIN_TEXT_SIZE);
            mShrinkTextSize = a.getBoolean(R.styleable.AutoResizeTextView_shrinkTextSize, SHRINK_TEXT_SIZE);
            a.recycle();
        }
    }

    @Override
    public void setTextSize(float size) {
        mMaxTextSize = size;
        super.setTextSize(size);
    }

    /**
     * Returns the original, unmodified text of this widget
     * 
     * @return
     */
    public CharSequence getOriginalText() {
        // text has not been resized yet
        if (mOriginalText == null) {
            return getText();
        }
        return mOriginalText;
    }

    @Override
    public void setText(CharSequence text, BufferType type) {
        if (!mInMeasure) {
            mOriginalText = text.toString();
        }
        super.setText(text, type);
    }

    @SuppressLint("DrawAllocation")
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        mInMeasure = true;
        try {
            int availableWidth = MeasureSpec.getSize(widthMeasureSpec) - getCompoundPaddingLeft()
                    - getCompoundPaddingRight();
            int availableHeight = MeasureSpec.getSize(heightMeasureSpec) - getCompoundPaddingTop()
                    - getCompoundPaddingBottom();

            // Do not resize if the view does not have dimensions or there is no
            // text
            if (mOriginalText == null || mOriginalText.length() == 0 || availableWidth <= 0) {
                return;
            }

            TextPaint textPaint = getPaint();

            // start with the recorded max text size
            float targetTextSize = mMaxTextSize;
            String originalText = mOriginalText.toString();
            String finalText = originalText;

            Rect textSize = getTextSize(originalText, textPaint, targetTextSize);
            boolean textExceedsBounds = textSize.height() > availableHeight || textSize.width() > availableWidth;
            if (mShrinkTextSize && textExceedsBounds) {
                // check whether all lines can be rendered in the available
                // width / height without violating the bounds of the parent and
                // without using a text size that is smaller than the minimum
                // text size
                float heightMultiplier = availableHeight / (float) textSize.height();
                float widthMultiplier = availableWidth / (float) textSize.width();
                float multiplier = Math.min(heightMultiplier, widthMultiplier);
                targetTextSize = Math.max(targetTextSize * multiplier, mMinTextSize);

                // measure again
                textSize = getTextSize(finalText, textPaint, targetTextSize);
            }

            // we cannot shrink the height further when we hit the available
            // height, but we can shrink the width by applying an ellipsis on
            // each line
            if (textSize.width() > availableWidth) {
                StringBuilder modifiedText = new StringBuilder();
                String lines[] = originalText.split(System.getProperty("line.separator"));
                for (int i = 0; i < lines.length; i++) {
                    modifiedText.append(resizeLine(textPaint, lines[i], availableWidth));
                    // add the separator back to all but the last processed line
                    if (i != lines.length - 1) {
                        modifiedText.append(System.getProperty("line.separator"));
                    }
                }
                finalText = modifiedText.toString();

                // measure again
                textSize = getTextSize(finalText, textPaint, targetTextSize);
            }

            textPaint.setTextSize(targetTextSize);
            boolean isMultiline = finalText.indexOf('\n') > -1;
            // do not include extra font padding (for accents, ...) for
            // multiline texts, this will prevent proper placement with
            // Gravity.CENTER_VERTICAL
            if (isMultiline) {
                setLineSpacing(LINE_SPACING_EXTRA, LINE_SPACING_MULTIPLIER_MULTILINE);
                setIncludeFontPadding(false);
            } else {
                setLineSpacing(LINE_SPACING_EXTRA, LINE_SPACING_MULTIPLIER_SINGLELINE);
                setIncludeFontPadding(true);
            }

            // according to
            // <http://code.google.com/p/android/issues/detail?id=22493>
            // we have to add a unicode character to trigger the text centering
            // in ICS. this particular character is known as "zero-width" and
            // does no harm.
            setText(finalText + "\u200B");

            int measuredWidth = textSize.width() + getCompoundPaddingLeft() + getCompoundPaddingRight();
            int measuredHeight = textSize.height() + getCompoundPaddingTop() + getCompoundPaddingBottom();

            // expand the view to the parent's height in case it is smaller or
            // to the minimum height that has been set
            // FIXME: honor the vertical measure mode (EXACTLY vs AT_MOST) here
            // somehow
            measuredHeight = Math.max(measuredHeight, MeasureSpec.getSize(heightMeasureSpec));
            setMeasuredDimension(measuredWidth, measuredHeight);
        } finally {
            mInMeasure = false;
        }
    }

    private Rect getTextSize(String text, TextPaint textPaint, float textSize) {
        textPaint.setTextSize(textSize);
        // StaticLayout depends on a given width in which it should lay out the
        // text (and optionally also split into separate lines).
        // Therefor we calculate the current text width manually and start with
        // a fake (read: maxmimum) width for the height calculation.
        // We do _not_ use layout.getLineWidth() here since this returns
        // slightly smaller numbers and therefor would lead to exceeded text box
        // drawing.
        StaticLayout layout = new StaticLayout(text, textPaint, Integer.MAX_VALUE, Alignment.ALIGN_NORMAL, 1f, 0f, true);
        int textWidth = 0;
        String lines[] = text.split(System.getProperty("line.separator"));
        for (int i = 0; i < lines.length; ++i) {
            textWidth = Math.max(textWidth, measureTextWidth(textPaint, lines[i]));
        }
        return new Rect(0, 0, textWidth, layout.getHeight());
    }

    private String resizeLine(TextPaint textPaint, String line, int availableWidth) {
        checkArgument(line != null && line.length() > 0, "expected non-empty string");
        int textWidth = measureTextWidth(textPaint, line);
        int lastDeletePos = -1;
        StringBuilder builder = new StringBuilder(line);
        while (textWidth > availableWidth && builder.length() > 0) {
            lastDeletePos = builder.length() / 2;
            builder.deleteCharAt(builder.length() / 2);
            // don't forget to measure the ellipsis character as well; it
            // doesn't matter where it is located in the line, it just has to be
            // there, since there are no (known) ligatures that use this glyph
            String textToMeasure = builder.toString() + ELLIPSIS;
            textWidth = measureTextWidth(textPaint, textToMeasure);
        }
        if (lastDeletePos > -1) {
            builder.insert(lastDeletePos, ELLIPSIS);
        }
        return builder.toString();
    }

    // there are several methods in Android to determine the text width, namely
    // getBounds() and measureText().
    // The latter works for us the best as it gives us the best / nearest
    // results without that our text canvas needs to wrap its text later on
    // again.
    private int measureTextWidth(TextPaint textPaint, String line) {
        return Math.round(textPaint.measureText(line));
    }
}

[修订于2012-11-21]

修正了省略号的位置(差一个错误) 重做文本大小计算;现在，总是测量包括换行符在内的全文，以解决当两个单独的测量线的高度相加与整个文本高度测量结果不相同时的问题 而不是循环寻找最小的可用文本大小，只需在第一次测量后计算它

作为一名手机开发者，我很遗憾地发现没有任何原生的支持自动调整大小的功能。我的搜索没有找到任何对我有用的东西，最后，我花了大半个周末的时间创建了我自己的自动调整文本视图。我将在这里发布代码，希望它对其他人有用。

这个类使用带有原始文本视图的文本绘制的静态布局来测量高度。从那里，我后退2个字体像素，重新测量，直到我有一个合适的大小。在最后，如果文本仍然不合适，我附加一个省略号。我需要动画文本和重用视图，这似乎在我拥有的设备上工作得很好，似乎运行得足够快。

/**
 *               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 = 20;

    // 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 = 0;

    // 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;
        }

        if (getTransformationMethod() != null) {
            text = getTransformationMethod().getTransformation(text, this);
        }

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

        // Store the current text size
        float oldTextSize = textPaint.getTextSize();
        // If there is a max text size set, use the lesser of that and the default text size
        float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize;

        // Get the required text height
        int textHeight = getTextHeight(text, textPaint, width, targetTextSize);

        // Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes
        while (textHeight > height && targetTextSize > mMinTextSize) {
            targetTextSize = Math.max(targetTextSize - 2, mMinTextSize);
            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 paint = new TextPaint(textPaint);
            // Draw using a static layout
            StaticLayout layout = new StaticLayout(text, paint, 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 = textPaint.measureText(mEllipsis);

                    // Trim characters off until we have enough room to draw the ellipsis
                    while (width < lineWidth + ellipseWidth) {
                        lineWidth = textPaint.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 paint, 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 paintCopy = new TextPaint(paint);
        // Update the text paint object
        paintCopy.setTextSize(textSize);
        // Measure using a static layout
        StaticLayout layout = new StaticLayout(source, paintCopy, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
        return layout.getHeight();
    }

}

警告。有一个影响Android 3.1 - 4.04的重要修复错误，导致所有AutoResizingTextView小部件无法工作。请阅读:https://stackoverflow.com/a/21851157/2075875

更新:下面的代码也满足了一个理想的AutoScaleTextView的要求，如这里所述:自动适合Android的TextView，并被标记为赢家。

更新2:增加了对maxlines的支持，现在在API级别16之前工作正常。

更新3:支持android: drawablleft, android:drawableRight, android:drawableTop和android:drawableBottom标签添加，感谢MartinH在这里的简单修复。

我的要求有点不同。我需要一种有效的方法来调整大小，因为我是动画一个整数从，可能是0 ~4000在TextView在2秒内，我想相应地调整大小。我的解决方法有点不同。这是最终的结果:

以及产生它的代码:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="16dp" >

    <com.vj.widgets.AutoResizeTextView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:ellipsize="none"
        android:maxLines="2"
        android:text="Auto Resized Text, max 2 lines"
        android:textSize="100sp" /> <!-- maximum size -->

    <com.vj.widgets.AutoResizeTextView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:ellipsize="none"
        android:gravity="center"
        android:maxLines="1"
        android:text="Auto Resized Text, max 1 line"
        android:textSize="100sp" /> <!-- maximum size -->

    <com.vj.widgets.AutoResizeTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Auto Resized Text"
        android:textSize="500sp" /> <!-- maximum size -->

</LinearLayout>

最后是java代码:

import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.RectF;
import android.os.Build;
import android.text.Layout.Alignment;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.SparseIntArray;
import android.util.TypedValue;
import android.widget.TextView;

public class AutoResizeTextView extends TextView {
private interface SizeTester {
    /**
     * 
     * @param suggestedSize
     *            Size of text to be tested
     * @param availableSpace
     *            available space in which text must fit
     * @return an integer < 0 if after applying {@code suggestedSize} to
     *         text, it takes less space than {@code availableSpace}, > 0
     *         otherwise
     */
    public int onTestSize(int suggestedSize, RectF availableSpace);
}

private RectF mTextRect = new RectF();

private RectF mAvailableSpaceRect;

private SparseIntArray mTextCachedSizes;

private TextPaint mPaint;

private float mMaxTextSize;

private float mSpacingMult = 1.0f;

private float mSpacingAdd = 0.0f;

private float mMinTextSize = 20;

private int mWidthLimit;

private static final int NO_LINE_LIMIT = -1;
private int mMaxLines;

private boolean mEnableSizeCache = true;
private boolean mInitiallized;

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

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

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

private void initialize() {
    mPaint = new TextPaint(getPaint());
    mMaxTextSize = getTextSize();
    mAvailableSpaceRect = new RectF();
    mTextCachedSizes = new SparseIntArray();
    if (mMaxLines == 0) {
        // no value was assigned during construction
        mMaxLines = NO_LINE_LIMIT;
    }
    mInitiallized = true;
}

@Override
public void setText(final CharSequence text, BufferType type) {
    super.setText(text, type);
    adjustTextSize(text.toString());
}

@Override
public void setTextSize(float size) {
    mMaxTextSize = size;
    mTextCachedSizes.clear();
    adjustTextSize(getText().toString());
}

@Override
public void setMaxLines(int maxlines) {
    super.setMaxLines(maxlines);
    mMaxLines = maxlines;
    reAdjust();
}

public int getMaxLines() {
    return mMaxLines;
}

@Override
public void setSingleLine() {
    super.setSingleLine();
    mMaxLines = 1;
    reAdjust();
}

@Override
public void setSingleLine(boolean singleLine) {
    super.setSingleLine(singleLine);
    if (singleLine) {
        mMaxLines = 1;
    } else {
        mMaxLines = NO_LINE_LIMIT;
    }
    reAdjust();
}

@Override
public void setLines(int lines) {
    super.setLines(lines);
    mMaxLines = lines;
    reAdjust();
}

@Override
public void setTextSize(int unit, float size) {
    Context c = getContext();
    Resources r;

    if (c == null)
        r = Resources.getSystem();
    else
        r = c.getResources();
    mMaxTextSize = TypedValue.applyDimension(unit, size,
            r.getDisplayMetrics());
    mTextCachedSizes.clear();
    adjustTextSize(getText().toString());
}

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

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

private void reAdjust() {
    adjustTextSize(getText().toString());
}

private void adjustTextSize(String string) {
    if (!mInitiallized) {
        return;
    }
    int startSize = (int) mMinTextSize;
    int heightLimit = getMeasuredHeight() - getCompoundPaddingBottom()
        - getCompoundPaddingTop();
    mWidthLimit = getMeasuredWidth() - getCompoundPaddingLeft()
        - getCompoundPaddingRight();
    mAvailableSpaceRect.right = mWidthLimit;
    mAvailableSpaceRect.bottom = heightLimit;
    super.setTextSize(
            TypedValue.COMPLEX_UNIT_PX,
            efficientTextSizeSearch(startSize, (int) mMaxTextSize,
                    mSizeTester, mAvailableSpaceRect));
}

private final SizeTester mSizeTester = new SizeTester() {
    @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
    @Override
    public int onTestSize(int suggestedSize, RectF availableSPace) {
        mPaint.setTextSize(suggestedSize);
        String text = getText().toString();
        boolean singleline = getMaxLines() == 1;
        if (singleline) {
            mTextRect.bottom = mPaint.getFontSpacing();
            mTextRect.right = mPaint.measureText(text);
        } else {
            StaticLayout layout = new StaticLayout(text, mPaint,
                    mWidthLimit, Alignment.ALIGN_NORMAL, mSpacingMult,
                    mSpacingAdd, true);
            // return early if we have more lines
            if (getMaxLines() != NO_LINE_LIMIT
                    && layout.getLineCount() > getMaxLines()) {
                return 1;
            }
            mTextRect.bottom = layout.getHeight();
            int maxWidth = -1;
            for (int i = 0; i < layout.getLineCount(); i++) {
                if (maxWidth < layout.getLineWidth(i)) {
                    maxWidth = (int) layout.getLineWidth(i);
                }
            }
            mTextRect.right = maxWidth;
        }

        mTextRect.offsetTo(0, 0);
        if (availableSPace.contains(mTextRect)) {
            // may be too small, don't worry we will find the best match
            return -1;
        } else {
            // too big
            return 1;
        }
    }
};

/**
 * Enables or disables size caching, enabling it will improve performance
 * where you are animating a value inside TextView. This stores the font
 * size against getText().length() Be careful though while enabling it as 0
 * takes more space than 1 on some fonts and so on.
 * 
 * @param enable
 *            enable font size caching
 */
public void enableSizeCache(boolean enable) {
    mEnableSizeCache = enable;
    mTextCachedSizes.clear();
    adjustTextSize(getText().toString());
}

private int efficientTextSizeSearch(int start, int end,
        SizeTester sizeTester, RectF availableSpace) {
    if (!mEnableSizeCache) {
        return binarySearch(start, end, sizeTester, availableSpace);
    }
    String text = getText().toString();
    int key = text == null ? 0 : text.length();
    int size = mTextCachedSizes.get(key);
    if (size != 0) {
        return size;
    }
    size = binarySearch(start, end, sizeTester, availableSpace);
    mTextCachedSizes.put(key, size);
    return size;
}

private static int binarySearch(int start, int end, SizeTester sizeTester,
        RectF availableSpace) {
    int lastBest = start;
    int lo = start;
    int hi = end - 1;
    int mid = 0;
    while (lo <= hi) {
        mid = (lo + hi) >>> 1;
        int midValCmp = sizeTester.onTestSize(mid, availableSpace);
        if (midValCmp < 0) {
            lastBest = lo;
            lo = mid + 1;
        } else if (midValCmp > 0) {
            hi = mid - 1;
            lastBest = hi;
        } else {
            return mid;
        }
    }
    // make sure to return last best
    // this is what should always be returned
    return lastBest;

}

@Override
protected void onTextChanged(final CharSequence text, final int start,
        final int before, final int after) {
    super.onTextChanged(text, start, before, after);
    reAdjust();
}

@Override
protected void onSizeChanged(int width, int height, int oldwidth,
        int oldheight) {
    mTextCachedSizes.clear();
    super.onSizeChanged(width, height, oldwidth, oldheight);
    if (width != oldwidth || height != oldheight) {
        reAdjust();
    }
}
}

我希望这对你有所帮助

import android.content.Context;
import android.graphics.Rect;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.widget.TextView;

/* Based on 
 * from http://stackoverflow.com/questions/2617266/how-to-adjust-text-font-size-to-fit-textview
 */
public class FontFitTextView extends TextView {

private static float MAX_TEXT_SIZE = 20;

public FontFitTextView(Context context) {
    this(context, null);
}

public FontFitTextView(Context context, AttributeSet attrs) {
    super(context, attrs);

    float size = this.getTextSize();
    if (size > MAX_TEXT_SIZE)
        setTextSize(MAX_TEXT_SIZE);
}

private void refitText(String text, int textWidth) {
    if (textWidth > 0) {
        float availableWidth = textWidth - this.getPaddingLeft()
                - this.getPaddingRight();

        TextPaint tp = getPaint();
        Rect rect = new Rect();
        tp.getTextBounds(text, 0, text.length(), rect);
        float size = rect.width();

        if (size > availableWidth)
            setTextScaleX(availableWidth / size);
    }
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
    int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
    refitText(this.getText().toString(), parentWidth);
    this.setMeasuredDimension(parentWidth, parentHeight);
}

@Override
protected void onTextChanged(final CharSequence text, final int start,
        final int before, final int after) {
    refitText(text.toString(), this.getWidth());
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    if (w != oldw) {
        refitText(this.getText().toString(), w);
    }
}
}

注意:我使用MAX_TEXT_SIZE在文本大小大于20的情况下，因为我不想让大字体适用于我的视图，如果这不是你的情况下，你可以简单地删除它。

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。: -)