修改supportV4中的PagerTitleStrip的文字显示效果

在使用中，发现PagerTitleStrip显示的标题问题无法设置文字颜色和大小，经过查找代码，明显这个问题在4.0以后的新版本中已经被解决，那么现在如何解决这个问题呢？

其实很简单，用反射

 

mPagerTitleStrip = (PagerTitleStrip) findViewById(R.id.pagertitle);try {Field field=mPagerTitleStrip.getClass().getDeclaredField("mCurrText");field.setAccessible(true);TextView view=(TextView) field.get(mPagerTitleStrip);view.setTextColor(Color.BLACK);} catch (IllegalArgumentException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();} catch (SecurityException e) {e.printStackTrace();} catch (NoSuchFieldException e) {e.printStackTrace();}

PagerTitleStrip控件中显示文字的三个TextView，用反射获得这3个TextView，对其进行设置即可。

附带：PagerTitleStrip源码

/* * Copyright (C) 2011 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package android.support.v4.view;import android.content.Context;import android.content.res.TypedArray;import android.database.DataSetObserver;import android.graphics.drawable.Drawable;import android.text.TextUtils.TruncateAt;import android.util.AttributeSet;import android.util.TypedValue;import android.view.ViewGroup;import android.view.ViewParent;import android.widget.TextView;/** * PagerTitleStrip is a non-interactive indicator of the current, next, * and previous pages of a {@link ViewPager}. It is intended to be used as a * child view of a ViewPager widget in your XML layout. * Add it as a child of a ViewPager in your layout file and set its * android:layout_gravity to TOP or BOTTOM to pin it to the top or bottom * of the ViewPager. The title from each page is supplied by the method * {@link PagerAdapter#getPageTitle(int)} in the adapter supplied to * the ViewPager. */public class PagerTitleStrip extends ViewGroup implements ViewPager.Decor {    private static final String TAG = "PagerTitleStrip";    ViewPager mPager;    private TextView mPrevText;    private TextView mCurrText;    private TextView mNextText;    private int mLastKnownCurrentPage = -1;    private float mLastKnownPositionOffset = -1;    private int mScaledTextSpacing;    private boolean mUpdatingText;    private boolean mUpdatingPositions;    private final PageListener mPageListener = new PageListener();    private static final int[] ATTRS = new int[] {        android.R.attr.textAppearance,        android.R.attr.textColor,        android.R.attr.textSize    };    private int mNonPrimaryAlpha;    int mTextColor;    private static final int SIDE_ALPHA = 0x99; // single-byte alpha, 0 = invisible, FF = opaque    private static final int TEXT_SPACING = 16; // dip    public PagerTitleStrip(Context context) {        this(context, null);    }    public PagerTitleStrip(Context context, AttributeSet attrs) {        super(context, attrs);        addView(mPrevText = new TextView(context));        addView(mCurrText = new TextView(context));        addView(mNextText = new TextView(context));        final TypedArray a = context.obtainStyledAttributes(attrs, ATTRS);        final int textAppearance = a.getResourceId(0, 0);        if (textAppearance != 0) {            mPrevText.setTextAppearance(context, textAppearance);            mCurrText.setTextAppearance(context, textAppearance);            mNextText.setTextAppearance(context, textAppearance);        }        if (a.hasValue(1)) {            final int textColor = a.getColor(1, 0);            mPrevText.setTextColor(textColor);            mCurrText.setTextColor(textColor);            mNextText.setTextColor(textColor);        }        final int textSize = a.getDimensionPixelSize(2, 0);        if (textSize != 0) {            mPrevText.setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize);            mCurrText.setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize);            mNextText.setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize);        }        a.recycle();        mTextColor = mCurrText.getTextColors().getDefaultColor();        setNonPrimaryAlpha(SIDE_ALPHA);        mPrevText.setEllipsize(TruncateAt.END);        mCurrText.setEllipsize(TruncateAt.END);        mNextText.setEllipsize(TruncateAt.END);        mPrevText.setSingleLine();        mCurrText.setSingleLine();        mNextText.setSingleLine();        final float density = context.getResources().getDisplayMetrics().density;        mScaledTextSpacing = (int) (TEXT_SPACING * density);    }    @Override    protected void onAttachedToWindow() {        super.onAttachedToWindow();        final ViewParent parent = getParent();        if (!(parent instanceof ViewPager)) {            throw new IllegalStateException(                    "PagerTitleStrip must be a direct child of a ViewPager.");        }        final ViewPager pager = (ViewPager) parent;        final PagerAdapter adapter = pager.getAdapter();        pager.setInternalPageChangeListener(mPageListener);        pager.setOnAdapterChangeListener(mPageListener);        mPager = pager;        updateAdapter(null, adapter);    }    @Override    protected void onDetachedFromWindow() {        updateAdapter(mPager.getAdapter(), null);        mPager.setInternalPageChangeListener(null);        mPager.setOnAdapterChangeListener(null);        mPager = null;    }    /**     * Set the alpha value used for non-primary page titles.     *     * @param alpha Opacity value in the range 0-1f     */    public void setNonPrimaryAlpha(float alpha) {        mNonPrimaryAlpha = (int) (alpha * 255) & 0xFF;        final int transparentColor = (mNonPrimaryAlpha << 24) | (mTextColor & 0xFFFFFF);        mPrevText.setTextColor(transparentColor);        mNextText.setTextColor(transparentColor);    }        /**     * Set the color value used as the base color for all displayed page titles.     * Alpha will be ignored for non-primary page titles. See {@link #setNonPrimaryAlpha(float)}.     *     * @param color Color hex code in 0xAARRGGBB format     */    public void setTextColor(int color) {        mTextColor = color;        mCurrText.setTextColor(color);        final int transparentColor = (mNonPrimaryAlpha << 24) | (mTextColor & 0xFFFFFF);        mPrevText.setTextColor(transparentColor);        mNextText.setTextColor(transparentColor);    }        void updateText(int currentItem, PagerAdapter adapter) {        final int itemCount = adapter != null ? adapter.getCount() : 0;        mUpdatingText = true;        CharSequence text = null;        if (currentItem >= 1 && adapter != null) {            text = adapter.getPageTitle(currentItem - 1);        }        mPrevText.setText(text);        mCurrText.setText(adapter != null ? adapter.getPageTitle(currentItem) : null);        text = null;        if (currentItem + 1 < itemCount && adapter != null) {            text = adapter.getPageTitle(currentItem + 1);        }        mNextText.setText(text);        // Measure everything        final int width = getWidth() - getPaddingLeft() - getPaddingRight();        final int childHeight = getHeight() - getPaddingTop() - getPaddingBottom();        final int childWidthSpec = MeasureSpec.makeMeasureSpec((int) (width * 0.8f),                MeasureSpec.AT_MOST);        final int childHeightSpec = MeasureSpec.makeMeasureSpec(childHeight, MeasureSpec.EXACTLY);        mPrevText.measure(childWidthSpec, childHeightSpec);        mCurrText.measure(childWidthSpec, childHeightSpec);        mNextText.measure(childWidthSpec, childHeightSpec);        mLastKnownCurrentPage = currentItem;        if (!mUpdatingPositions) {            updateTextPositions(currentItem, mLastKnownPositionOffset);        }        mUpdatingText = false;    }    @Override    public void requestLayout() {        if (!mUpdatingText) {            super.requestLayout();        }    }    void updateAdapter(PagerAdapter oldAdapter, PagerAdapter newAdapter) {        if (oldAdapter != null) {            oldAdapter.unregisterDataSetObserver(mPageListener);        }        if (newAdapter != null) {            newAdapter.registerDataSetObserver(mPageListener);        }        if (mPager != null) {            mLastKnownCurrentPage = -1;            mLastKnownPositionOffset = -1;            updateText(mPager.getCurrentItem(), newAdapter);            requestLayout();        }    }    void updateTextPositions(int position, float positionOffset) {        if (position != mLastKnownCurrentPage) {            updateText(position, mPager.getAdapter());        } else if (positionOffset == mLastKnownPositionOffset) {            return;        }        mUpdatingPositions = true;        final int prevWidth = mPrevText.getMeasuredWidth();        final int currWidth = mCurrText.getMeasuredWidth();        final int nextWidth = mNextText.getMeasuredWidth();        final int halfCurrWidth = currWidth / 2;        final int stripWidth = getWidth();        final int paddingLeft = getPaddingLeft();        final int paddingRight = getPaddingRight();        final int paddingTop = getPaddingTop();        final int textPaddedLeft = paddingLeft + halfCurrWidth;        final int textPaddedRight = paddingRight + halfCurrWidth;        final int contentWidth = stripWidth - textPaddedLeft - textPaddedRight;        float currOffset = positionOffset + 0.5f;        if (currOffset > 1.f) {            currOffset -= 1.f;        }        final int currCenter = stripWidth - textPaddedRight - (int) (contentWidth * currOffset);        final int currLeft = currCenter - currWidth / 2;        final int currRight = currLeft + currWidth;        mCurrText.layout(currLeft, paddingTop, currRight,                paddingTop + mCurrText.getMeasuredHeight());        final int prevLeft = Math.min(paddingLeft, currLeft - mScaledTextSpacing - prevWidth);        mPrevText.layout(prevLeft, paddingTop, prevLeft + prevWidth,                paddingTop + mPrevText.getMeasuredHeight());        final int nextLeft = Math.max(stripWidth - paddingRight - nextWidth,                currRight + mScaledTextSpacing);        mNextText.layout(nextLeft, paddingTop, nextLeft + nextWidth,                paddingTop + mNextText.getMeasuredHeight());        mLastKnownPositionOffset = positionOffset;        mUpdatingPositions = false;    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);        final int widthSize = MeasureSpec.getSize(widthMeasureSpec);        final int heightSize = MeasureSpec.getSize(heightMeasureSpec);        if (widthMode != MeasureSpec.EXACTLY) {            throw new IllegalStateException("Must measure with an exact width");        }        int childHeight = heightSize;        int minHeight = 0;        int padding = 0;        final Drawable bg = getBackground();        if (bg != null) {            minHeight = bg.getIntrinsicHeight();        }        padding = getPaddingTop() + getPaddingBottom();        childHeight -= padding;        final int childWidthSpec = MeasureSpec.makeMeasureSpec((int) (widthSize * 0.8f),                MeasureSpec.AT_MOST);        final int childHeightSpec = MeasureSpec.makeMeasureSpec(childHeight, heightMode);        mPrevText.measure(childWidthSpec, childHeightSpec);        mCurrText.measure(childWidthSpec, childHeightSpec);        mNextText.measure(childWidthSpec, childHeightSpec);        if (heightMode == MeasureSpec.EXACTLY) {            setMeasuredDimension(widthSize, heightSize);        } else {            int textHeight = mCurrText.getMeasuredHeight();            setMeasuredDimension(widthSize, Math.max(minHeight, textHeight + padding));        }    }    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b) {        if (mPager != null) {            updateTextPositions(mPager.getCurrentItem(), 0.f);        }    }    private class PageListener extends DataSetObserver implements ViewPager.OnPageChangeListener,            ViewPager.OnAdapterChangeListener {        private int mScrollState;        @Override        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {            if (positionOffset > 0.5f) {                // Consider ourselves to be on the next page when we're 50% of the way there.                position++;            }            updateTextPositions(position, positionOffset);        }        @Override        public void onPageSelected(int position) {            if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {                // Only update the text here if we're not dragging or settling.                updateText(mPager.getCurrentItem(), mPager.getAdapter());            }        }        @Override        public void onPageScrollStateChanged(int state) {            mScrollState = state;        }        @Override        public void onAdapterChanged(PagerAdapter oldAdapter, PagerAdapter newAdapter) {            updateAdapter(oldAdapter, newAdapter);        }        @Override        public void onChanged() {            updateText(mPager.getCurrentItem(), mPager.getAdapter());        }    }}