安卓开发之滑动列表中顶部可以居中滑动的listview（仿安卓联系人音序置顶）

listview

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.AdapterView;
import android.widget.HeaderViewListAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;

public class PinnedHeaderListView extends ListView implements OnScrollListener {

    private OnScrollListener mOnScrollListener;

    public static interface PinnedSectionedHeaderAdapter {
        public boolean isSectionHeader(int position);

        public int getSectionForPosition(int position);

        public View getSectionHeaderView(int section, View convertView, ViewGroup parent);

        public int getSectionHeaderViewType(int section);

        public int getCount();

    }

    private PinnedSectionedHeaderAdapter mAdapter;
    private View mCurrentHeader;
    private int mCurrentHeaderViewType = 0;
    private float mHeaderOffset;
    private boolean mShouldPin = true;
    private int mCurrentSection = 0;
    private int mWidthMode;
    private int mHeightMode;

    public PinnedHeaderListView(Context context) {
        super(context);
        super.setOnScrollListener(this);
    }

    public PinnedHeaderListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        super.setOnScrollListener(this);
    }

    public PinnedHeaderListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        super.setOnScrollListener(this);
    }

    public void setPinHeaders(boolean shouldPin) {
        mShouldPin = shouldPin;
    }

    @Override
    public void setAdapter(ListAdapter adapter) {
        mCurrentHeader = null;
        mAdapter = (PinnedSectionedHeaderAdapter) adapter;
        super.setAdapter(adapter);
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        if (mOnScrollListener != null) {
            mOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
        }

        if (mAdapter == null || mAdapter.getCount() == 0 || !mShouldPin || (firstVisibleItem null;
            mHeaderOffset = 0.0f;
            for (int i = firstVisibleItem; i if (header != null) {
                    header.setVisibility(VISIBLE);
                }
            }
            return;
        }

        firstVisibleItem -= getHeaderViewsCount();

        int section = mAdapter.getSectionForPosition(firstVisibleItem);
        int viewType = mAdapter.getSectionHeaderViewType(section);
        mCurrentHeader = getSectionHeaderView(section, mCurrentHeaderViewType != viewType ? null : mCurrentHeader);
        ensurePinnedHeaderLayout(mCurrentHeader);
        mCurrentHeaderViewType = viewType;

        mHeaderOffset = 0.0f;

        for (int i = firstVisibleItem; i if (mAdapter.isSectionHeader(i)) {
                View header = getChildAt(i - firstVisibleItem);
                float headerTop = header.getTop();
                float pinnedHeaderHeight = mCurrentHeader.getMeasuredHeight();
                header.setVisibility(VISIBLE);
                if (pinnedHeaderHeight >= headerTop && headerTop > 0) {
                    mHeaderOffset = headerTop - header.getHeight();
                } else if (headerTop <= 0) {
                    header.setVisibility(INVISIBLE);
                }
            }
        }

        invalidate();
    }

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        if (mOnScrollListener != null) {
            mOnScrollListener.onScrollStateChanged(view, scrollState);
        }
    }

    private View getSectionHeaderView(int section, View oldView) {
        boolean shouldLayout = section != mCurrentSection || oldView == null;

        View view = mAdapter.getSectionHeaderView(section, oldView, this);
        if (shouldLayout) {
            // a new section, thus a new header. We should lay it out again
            ensurePinnedHeaderLayout(view);
            mCurrentSection = section;
        }
        return view;
    }

    private void ensurePinnedHeaderLayout(View header) {
        if (header.isLayoutRequested()) {
            int widthSpec = MeasureSpec.makeMeasureSpec(getMeasuredWidth(), mWidthMode);

            int heightSpec;
            ViewGroup.LayoutParams layoutParams = header.getLayoutParams();
            if (layoutParams != null && layoutParams.height > 0) {
                heightSpec = MeasureSpec.makeMeasureSpec(layoutParams.height, MeasureSpec.EXACTLY);
            } else {
                heightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
            }
            header.measure(widthSpec, heightSpec);
            header.layout(0, 0, header.getMeasuredWidth(), header.getMeasuredHeight());
        }
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);
        if (mAdapter == null || !mShouldPin || mCurrentHeader == null)
            return;
        int saveCount = canvas.save();
        canvas.translate(0, mHeaderOffset);
        canvas.clipRect(0, 0, getWidth(), mCurrentHeader.getMeasuredHeight()); // needed
        // for
        // <
        // HONEYCOMB
        mCurrentHeader.draw(canvas);
        canvas.restoreToCount(saveCount);
    }

    @Override
    public void setOnScrollListener(OnScrollListener l) {
        mOnScrollListener= l;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        mWidthMode = MeasureSpec.getMode(widthMeasureSpec);
        mHeightMode = MeasureSpec.getMode(heightMeasureSpec);
    }

    public void setOnItemClickListener(OnItemClickListener listener) {
        super.setOnItemClickListener(listener);
    }

    public static abstract class OnItemClickListener implements AdapterView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView adapterView, View view, int rawPosition, long id) {
            SectionedBaseAdapter adapter;
            if (adapterView.getAdapter().getClass().equals(HeaderViewListAdapter.class)) {
                HeaderViewListAdapter wrapperAdapter = (HeaderViewListAdapter) adapterView.getAdapter();
                adapter = (SectionedBaseAdapter) wrapperAdapter.getWrappedAdapter();
            } else {
                adapter = (SectionedBaseAdapter) adapterView.getAdapter();
            }
            int section = adapter.getSectionForPosition(rawPosition);
            int position = adapter.getPositionInSectionForPosition(rawPosition);

            if (position == -1) {
                onSectionClick(adapterView, view, section, id);
            } else {
                onItemClick(adapterView, view, section, position, id);
            }
        }

        public abstract void onItemClick(AdapterView adapterView, View view, int section, int position, long id);

        public abstract void onSectionClick(AdapterView adapterView, View view, int section, long id);

    }
}

adapter

import android.util.SparseArray;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

public abstract class SectionedBaseAdapter extends BaseAdapter implements PinnedHeaderListView.PinnedSectionedHeaderAdapter {

    private static int HEADER_VIEW_TYPE = 0;
    private static int ITEM_VIEW_TYPE = 0;

    /** * Holds the calculated values of @{link getPositionInSectionForPosition} */
    private SparseArray mSectionPositionCache;
    /** * Holds the calculated values of @{link getSectionForPosition} */
    private SparseArray mSectionCache;
    /** * Holds the calculated values of @{link getCountForSection} */
    private SparseArray mSectionCountCache;

    /** * Caches the item count */
    private int mCount;
    /** * Caches the section count */
    private int mSectionCount;

    public SectionedBaseAdapter() {
        super();
        mSectiOnCache= new SparseArray();
        mSectiOnPositionCache= new SparseArray();
        mSectiOnCountCache= new SparseArray();
        mCount = -1;
        mSectiOnCount= -1;
    }

    @Override
    public void notifyDataSetChanged() {
        mSectionCache.clear();
        mSectionPositionCache.clear();
        mSectionCountCache.clear();
        mCount = -1;
        mSectiOnCount= -1;
        super.notifyDataSetChanged();
    }

    @Override
    public void notifyDataSetInvalidated() {
        mSectionCache.clear();
        mSectionPositionCache.clear();
        mSectionCountCache.clear();
        mCount = -1;
        mSectiOnCount= -1;
        super.notifyDataSetInvalidated();
    }

    @Override
    public final int getCount() {
        if (mCount >= 0) {
            return mCount;
        }
        int count = 0;
        for (int i = 0; i // for the header view
        }
        mCount = count;
        return count;
    }

    @Override
    public final Object getItem(int position) {
        return getItem(getSectionForPosition(position), getPositionInSectionForPosition(position));
    }

    @Override
    public final long getItemId(int position) {
        return getItemId(getSectionForPosition(position), getPositionInSectionForPosition(position));
    }

    @Override
    public final View getView(int position, View convertView, ViewGroup parent) {
        if (isSectionHeader(position)) {
            return getSectionHeaderView(getSectionForPosition(position), convertView, parent);
        }
        return getItemView(getSectionForPosition(position), getPositionInSectionForPosition(position), convertView, parent);
    }

    @Override
    public final int getItemViewType(int position) {
        if (isSectionHeader(position)) {
            return getItemViewTypeCount() + getSectionHeaderViewType(getSectionForPosition(position));
        }
        return getItemViewType(getSectionForPosition(position), getPositionInSectionForPosition(position));
    }

    @Override
    public final int getViewTypeCount() {
        return getItemViewTypeCount() + getSectionHeaderViewTypeCount();
    }

    public final int getSectionForPosition(int position) {
        // first try to retrieve values from cache
        Integer cachedSection = mSectionCache.get(position);
        if (cachedSection != null) {
            return cachedSection;
        }
        int sectiOnStart= 0;
        for (int i = 0; i int sectiOnCount= internalGetCountForSection(i);
            int sectiOnEnd= sectionStart + sectionCount + 1;
            if (position >= sectionStart && position return i;
            }
            sectiOnStart= sectionEnd;
        }
        return 0;
    }

    public int getPositionInSectionForPosition(int position) {
        // first try to retrieve values from cache
        Integer cachedPosition = mSectionPositionCache.get(position);
        if (cachedPosition != null) {
            return cachedPosition;
        }
        int sectiOnStart= 0;
        for (int i = 0; i int sectiOnCount= internalGetCountForSection(i);
            int sectiOnEnd= sectionStart + sectionCount + 1;
            if (position >= sectionStart && position int positiOnInSection= position - sectionStart - 1;
                mSectionPositionCache.put(position, positionInSection);
                return positionInSection;
            }
            sectiOnStart= sectionEnd;
        }
        return 0;
    }

    public final boolean isSectionHeader(int position) {
        int sectiOnStart= 0;
        for (int i = 0; i if (position == sectionStart) {
                return true;
            } else if (position return false;
            }
            sectionStart += internalGetCountForSection(i) + 1;
        }
        return false;
    }

    public int getItemViewType(int section, int position) {
        return ITEM_VIEW_TYPE;
    }

    public int getItemViewTypeCount() {
        return 1;
    }

    public int getSectionHeaderViewType(int section) {
        return HEADER_VIEW_TYPE;
    }

    public int getSectionHeaderViewTypeCount() {
        return 1;
    }

    public abstract Object getItem(int section, int position);

    public abstract long getItemId(int section, int position);

    public abstract int getSectionCount();

    public abstract int getCountForSection(int section);

    public abstract View getItemView(int section, int position, View convertView, ViewGroup parent);

    public abstract View getSectionHeaderView(int section, View convertView, ViewGroup parent);

    private int internalGetCountForSection(int section) {
        Integer cachedSectiOnCount= mSectionCountCache.get(section);
        if (cachedSectionCount != null) {
            return cachedSectionCount;
        }
        int sectiOnCount= getCountForSection(section);
        mSectionCountCache.put(section, sectionCount);
        return sectionCount;
    }

    private int internalGetSectionCount() {
        if (mSectionCount >= 0) {
            return mSectionCount;
        }
        mSectiOnCount= getSectionCount();
        return mSectionCount;
    }

}