带下拉刷新，上拉加载以及带自定义头布局的GridView

一、引言

相信很多人都会遇到GridView，一般都会带有下拉刷新和上拉加载，于是我们可以使用第三方框架去实现，实现方式有很多，这里我就不一一列举了，这里我经常使用的是这个https://github.com/chrisbanes/Android-PullToRefresh，使用步骤自己百度，网上很多。如何在这基础上添加自定义头布局（例如轮播图）怎么做呢，此第三方的GridView并没有addHeadView()的方法，网上的方法很多，有的要么不带下拉上拉，有的要么实现起来麻烦（事件分发问题，复用问题，性能问题），还有的我没试过，这里我借鉴了网上的一个方法，小小地改了一下。

二、使用步骤

1、添加依赖：https://github.com/chrisbanes/Android-PullToRefresh下载library,添加依赖

2、创建两个类如下：这两个类来自网上，自己稍微修改了一下

HeadGridView:

import android.annotation.SuppressLint;
import android.content.Context;
import android.database.DataSetObservable;
import android.database.DataSetObserver;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Filter;
import android.widget.Filterable;
import android.widget.FrameLayout;
import android.widget.GridView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.WrapperListAdapter;

import java.util.ArrayList;
/**
 * A {@link GridView} that supports adding header rows in a
 * very similar way to {@link ListView}.
 * See {@link HeaderGridView#addHeaderView(View, Object, boolean)}
 */
@SuppressLint("NewApi")
public class HeaderGridView extends  GridView  {
    private static final String TAG = "HeaderGridView";
    /**
     * A class that represents a fixed view in a list, for example a header at the top
     * or a footer at the bottom.
     */
    private static class FixedViewInfo {
        /** The view to add to the grid */
        public View view;
        public ViewGroup viewContainer;
        /** The data backing the view. This is returned from {@link ListAdapter#getItem(int)}. */
        public Object data;
        /** true if the fixed view should be selectable in the grid */
        public boolean isSelectable;
    }
    private ArrayList mHeaderViewInfos = new ArrayList();
    private void initHeaderGridView() {
        super.setClipChildren(false);
    }
    public HeaderGridView(Context context) {
        super(context);
        initHeaderGridView();
    }
    public HeaderGridView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initHeaderGridView();
    }
    public HeaderGridView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        initHeaderGridView();
    }
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        ListAdapter adapter = getAdapter();
        if (adapter != null && adapter instanceof HeaderViewGridAdapter) {
            ((HeaderViewGridAdapter) adapter).setNumColumns(getNumColumns());
        }
    }
    @Override
    public void setClipChildren(boolean clipChildren) {
        // Ignore, since the header rows depend on not being clipped
    }
    /**
     * Add a fixed view to appear at the top of the grid. If addHeaderView is
     * called more than once, the views will appear in the order they were
     * added. Views added using this call can take focus if they want.
     * 

     * NOTE: Call this before calling setAdapter. This is so HeaderGridView can wrap
     * the supplied cursor with one that will also account for header views.
     *
     * @param v The view to add.
     * @param data Data to associate with this view
     * @param isSelectable whether the item is selectable
     */
    public void addHeaderView(View v, Object data, boolean isSelectable) {
        ListAdapter adapter = getAdapter();
        if (adapter != null && ! (adapter instanceof HeaderViewGridAdapter)) {
            throw new IllegalStateException(
                    "Cannot add header view to grid -- setAdapter has already been called.");
        }
        FixedViewInfo info = new FixedViewInfo();
        FrameLayout fl = new FullWidthFixedViewLayout(getContext());
        fl.addView(v);
        info.view = v;
        info.viewContainer = fl;
        info.data = data;
        info.isSelectable = isSelectable;
        mHeaderViewInfos.add(info);
        // in the case of re-adding a header view, or adding one later on,
        // we need to notify the observer
        if (adapter != null) {
            ((HeaderViewGridAdapter) adapter).notifyDataSetChanged();
        }
    }
    /**
     * Add a fixed view to appear at the top of the grid. If addHeaderView is
     * called more than once, the views will appear in the order they were
     * added. Views added using this call can take focus if they want.
     * 

     * NOTE: Call this before calling setAdapter. This is so HeaderGridView can wrap
     * the supplied cursor with one that will also account for header views.
     *
     * @param v The view to add.
     */
    public void addHeaderView(View v) {
        addHeaderView(v, null, true);
    }
    public int getHeaderViewCount() {
        return mHeaderViewInfos.size();
    }
    /**
     * Removes a previously-added header view.
     *
     * @param v The view to remove
     * @return true if the view was removed, false if the view was not a header
     *         view
     */
    public boolean removeHeaderView(View v) {
        if (mHeaderViewInfos.size() > 0) {
            boolean result = false;
            ListAdapter adapter = getAdapter();
            if (adapter != null && ((HeaderViewGridAdapter) adapter).removeHeader(v)) {
                result = true;
            }
            removeFixedViewInfo(v, mHeaderViewInfos);
            return result;
        }
        return false;
    }
    private void removeFixedViewInfo(View v, ArrayList where) {
        int len = where.size();
        for (int i = 0; i < len; ++i) {
            FixedViewInfo info = where.get(i);
            if (info.view == v) {
                where.remove(i);
                break;
            }
        }
    }
    @Override
    public void setAdapter(ListAdapter adapter) {
        if (mHeaderViewInfos.size() > 0) {
            HeaderViewGridAdapter hadapter = new HeaderViewGridAdapter(mHeaderViewInfos, adapter);
            int numColumns = getNumColumns();
            if (numColumns > 1) {
                hadapter.setNumColumns(numColumns);
            }
            super.setAdapter(hadapter);
        } else {
            super.setAdapter(adapter);
        }
    }
    private class FullWidthFixedViewLayout extends FrameLayout {
        public FullWidthFixedViewLayout(Context context) {
            super(context);
        }
        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            int targetWidth = HeaderGridView.this.getMeasuredWidth()
                    - HeaderGridView.this.getPaddingLeft()
                    - HeaderGridView.this.getPaddingRight();
            widthMeasureSpec = MeasureSpec.makeMeasureSpec(targetWidth,
                    MeasureSpec.getMode(widthMeasureSpec));
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }
    /**
     * ListAdapter used when a HeaderGridView has header views. This ListAdapter
     * wraps another one and also keeps track of the header views and their
     * associated data objects.
     *
This is intended as a base class; you will probably not need to
     * use this class directly in your own code.
     */
    private static class HeaderViewGridAdapter implements WrapperListAdapter, Filterable {
        // This is used to notify the container of updates relating to number of columns
        // or headers changing, which changes the number of placeholders needed
        private final DataSetObservable mDataSetObservable = new DataSetObservable();
        private final ListAdapter mAdapter;
        private int mNumColumns = 1;
        // This ArrayList is assumed to NOT be null.
        ArrayList mHeaderViewInfos;
        boolean mAreAllFixedViewsSelectable;
        private final boolean mIsFilterable;
        public HeaderViewGridAdapter(ArrayList headerViewInfos, ListAdapter adapter) {
            mAdapter = adapter;
            mIsFilterable = adapter instanceof Filterable;
            if (headerViewInfos == null) {
                throw new IllegalArgumentException("headerViewInfos cannot be null");
            }
            mHeaderViewInfos = headerViewInfos;
            mAreAllFixedViewsSelectable = areAllListInfosSelectable(mHeaderViewInfos);
        }
        public int getHeadersCount() {
            return mHeaderViewInfos.size();
        }
        @Override
        public boolean isEmpty() {
            return (mAdapter == null || mAdapter.isEmpty()) && getHeadersCount() == 0;
        }
        public void setNumColumns(int numColumns) {
            if (numColumns < 1) {
                throw new IllegalArgumentException("Number of columns must be 1 or more");
            }
            if (mNumColumns != numColumns) {
                mNumColumns = numColumns;
                notifyDataSetChanged();
            }
        }
        private boolean areAllListInfosSelectable(ArrayList infos) {
            if (infos != null) {
                for (FixedViewInfo info : infos) {
                    if (!info.isSelectable) {
                        return false;
                    }
                }
            }
            return true;
        }
        public boolean removeHeader(View v) {
            for (int i = 0; i < mHeaderViewInfos.size(); i++) {
                FixedViewInfo info = mHeaderViewInfos.get(i);
                if (info.view == v) {
                    mHeaderViewInfos.remove(i);
                    mAreAllFixedViewsSelectable = areAllListInfosSelectable(mHeaderViewInfos);
                    mDataSetObservable.notifyChanged();
                    return true;
                }
            }
            return false;
        }
        @Override
        public int getCount() {
            if (mAdapter != null) {
                return getHeadersCount() * mNumColumns + mAdapter.getCount();
            } else {
                return getHeadersCount() * mNumColumns;
            }
        }
        @Override
        public boolean areAllItemsEnabled() {
            if (mAdapter != null) {
                return mAreAllFixedViewsSelectable && mAdapter.areAllItemsEnabled();
            } else {
                return true;
            }
        }
        @Override
        public boolean isEnabled(int position) {
            // Header (negative positions will throw an ArrayIndexOutOfBoundsException)
            int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
            if (position < numHeadersAndPlaceholders) {
                return (position % mNumColumns == 0)
                        && mHeaderViewInfos.get(position / mNumColumns).isSelectable;
            }
            // Adapter
            final int adjPosition = position - numHeadersAndPlaceholders;
            int adapterCount = 0;
            if (mAdapter != null) {
                adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {
                    return mAdapter.isEnabled(adjPosition);
                }
            }
            throw new ArrayIndexOutOfBoundsException(position);
        }
        @Override
        public Object getItem(int position) {
            // Header (negative positions will throw an ArrayIndexOutOfBoundsException)
            int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
            if (position < numHeadersAndPlaceholders) {
                if (position % mNumColumns == 0) {
                    return mHeaderViewInfos.get(position / mNumColumns).data;
                }
                return null;
            }
            // Adapter
            final int adjPosition = position - numHeadersAndPlaceholders;
            int adapterCount = 0;
            if (mAdapter != null) {
                adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {
                    return mAdapter.getItem(adjPosition);
                }
            }
            throw new ArrayIndexOutOfBoundsException(position);
        }
        @Override
        public long getItemId(int position) {
            int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
            if (mAdapter != null && position >= numHeadersAndPlaceholders) {
                int adjPosition = position - numHeadersAndPlaceholders;
                int adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {
                    return mAdapter.getItemId(adjPosition);
                }
            }
            return -1;
        }
        @Override
        public boolean hasStableIds() {
            if (mAdapter != null) {
                return mAdapter.hasStableIds();
            }
            return false;
        }
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // Header (negative positions will throw an ArrayIndexOutOfBoundsException)
            int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns ;
            if (position < numHeadersAndPlaceholders) {
                View headerViewContainer = mHeaderViewInfos
                        .get(position / mNumColumns).viewContainer;
                if (position % mNumColumns == 0) {
                    return headerViewContainer;
                } else {
                    if (convertView == null) {
                        convertView = new View(parent.getContext());
                    }
                    // We need to do this because GridView uses the height of the last item
                    // in a row to determine the height for the entire row.
                    convertView.setVisibility(View.INVISIBLE);
                    convertView.setMinimumHeight(headerViewContainer.getHeight());
                    return convertView;
                }
            }
            // Adapter
            final int adjPosition = position - numHeadersAndPlaceholders;
            int adapterCount = 0;
            if (mAdapter != null) {
                adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {
                    return mAdapter.getView(adjPosition, convertView, parent);
                }
            }
            throw new ArrayIndexOutOfBoundsException(position);
        }
        @Override
        public int getItemViewType(int position) {
            int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
            if (position < numHeadersAndPlaceholders && (position % mNumColumns != 0)) {
                // Placeholders get the last view type number
                return mAdapter != null ? mAdapter.getViewTypeCount() : 1;
            }
            if (mAdapter != null && position >= numHeadersAndPlaceholders) {
                int adjPosition = position - numHeadersAndPlaceholders;
                int adapterCount = mAdapter.getCount();
                if (adjPosition < adapterCount) {
                    return mAdapter.getItemViewType(adjPosition);
                }
            }
            return AdapterView.ITEM_VIEW_TYPE_HEADER_OR_FOOTER;
        }
        @Override
        public int getViewTypeCount() {
            if (mAdapter != null) {
                return mAdapter.getViewTypeCount() + 1;
            }
            return 2;
        }
        @Override
        public void registerDataSetObserver(DataSetObserver observer) {
            mDataSetObservable.registerObserver(observer);
            if (mAdapter != null) {
                mAdapter.registerDataSetObserver(observer);
            }
        }
        @Override
        public void unregisterDataSetObserver(DataSetObserver observer) {
            mDataSetObservable.unregisterObserver(observer);
            if (mAdapter != null) {
                mAdapter.unregisterDataSetObserver(observer);
            }
        }
        @Override
        public Filter getFilter() {
            if (mIsFilterable) {
                return ((Filterable) mAdapter).getFilter();
            }
            return null;
        }
        @Override
        public ListAdapter getWrappedAdapter() {
            return mAdapter;
        }
        public void notifyDataSetChanged() {
            mDataSetObservable.notifyChanged();
        }
    }

}

PullToRefreshGridView:

/**
 * @author hf  2016-11-08 13:16
 * @version 1.0
 * @des
 * @版本 $Rev: 10638 $
 * @change $Author: hufan $  $Date: 2016-11-08 17:00:27 +0800 (周二, 08 十一月 2016) $
 * @des ${TODO}
 */

import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build.VERSION;
import android.os.Build.VERSION_CODES;
import android.util.AttributeSet;
import android.view.View;

import com.handmark.pulltorefresh.library.OverscrollHelper;
import com.handmark.pulltorefresh.library.PullToRefreshAdapterViewBase;
import com.handmark.pulltorefresh.library.internal.EmptyViewMethodAccessor;


public class PullToRefreshGridView extends PullToRefreshAdapterViewBase {

    public PullToRefreshGridView(Context context) {
        super(context);
    }

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

    public PullToRefreshGridView(Context context, Mode mode) {
        super(context, mode);
    }

    public PullToRefreshGridView(Context context, Mode mode, AnimationStyle style) {
        super(context, mode, style);
    }

    @Override
    public final Orientation getPullToRefreshScrollDirection() {
        return Orientation.VERTICAL;
    }

    private HeaderGridView gv;
    @Override
    protected final HeaderGridView createRefreshableView(final Context context, AttributeSet attrs) {

        if (VERSION.SDK_INT >= VERSION_CODES.GINGERBREAD) {
            gv = new InternalGridViewSDK9(context, attrs);
        } else {
            gv = new InternalGridView(context, attrs);
        }
        // Use Generated ID (from res/values/ids.xml)
        gv.setId(R.id.gridview);
        return gv;
    }

    public void initHeadView(final Context context,ViewCallback callback) {
        setCallback(callback);
        View view=mCallback.setHeadView();
        gv.addHeaderView(view);
    }

    class InternalGridView extends HeaderGridView implements EmptyViewMethodAccessor {

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

        @Override
        public void setEmptyView(View emptyView) {
            PullToRefreshGridView.this.setEmptyView(emptyView);
        }

        @Override
        public void setEmptyViewInternal(View emptyView) {
            super.setEmptyView(emptyView);
        }
    }

    @TargetApi(9)
    final class InternalGridViewSDK9 extends InternalGridView {

        public InternalGridViewSDK9(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

        @Override
        protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX,
                int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent) {

            final boolean returnValue = super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX,
                    scrollRangeY, maxOverScrollX, maxOverScrollY, isTouchEvent);

            // Does all of the hard work...
            OverscrollHelper.overScrollBy(PullToRefreshGridView.this, deltaX, scrollX, deltaY, scrollY, isTouchEvent);

            return returnValue;
        }
    }

    public interface ViewCallback {
        View setHeadView();
    }

    public void setCallback(ViewCallback viewCallback) {
        this.mCallback = viewCallback;
    }

    private ViewCallback mCallback;
}

三、在xml文件中引用，注意是自己改写的那个，高度要设为match_parent ，否则会不显示

<包名下PullToRefreshGridView
    android:id="@+id/jifen_gridView1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#e8ebed"
    android:cacheColorHint="@color/bg_light_grey"
    android:horizontalSpacing="@dimen/dp15"
    android:numColumns="2"
    android:overScrollMode="never"
    android:scrollbars="none"
    android:stretchMode="columnWidth"
    android:verticalSpacing="@dimen/dp8">
包名下PullToRefreshGridView>

四、初始化时，找到并设置GridView，调用了initHeadView方法才会显示头布局，不一定要写在这里

/**
 * 配置刷新参数
 */
private void DoSetRefresh() {
    mGridView.setMode(PullToRefreshBase.Mode.BOTH);
    mGridView.setShowIndicator(false);//隐藏方向标
    mGridView.setFocusable(true);
    mGridView.initHeadView(mContext, new PullToRefreshGridView.ViewCallback() {
        @Override
        public View setHeadView() {
            View view = View.inflate(mContext, LayoutResourcesId, null);
            //这里可以对你的头布局做自己的操作，比如说添加Banner
            return view;
        }
    });


    ILoadingLayout startLabels = mGridView
            .getLoadingLayoutProxy(true, false);
    startLabels.setPullLabel("下拉刷新...");// 刚下拉时，显示的提示
    startLabels.setRefreshingLabel("刷新中...");// 刷新时
    startLabels.setReleaseLabel("松开刷新数据...");// 下来达到一定距离时，显示的提示

    ILoadingLayout endLabels = mGridView.getLoadingLayoutProxy(
            false, true);
    endLabels.setPullLabel("上拉加载...");// 刚下拉时，显示的提示
    endLabels.setRefreshingLabel("加载中...");// 刷新时
    endLabels.setReleaseLabel("松开加载数据...");// 下来达到一定距离时，显示的提示
}

五、发起网络请求，得到数据之后设置Adapter

六、设置监听（省略），点击监听，头布局position从1开始，头布局下面position是从2开始

七、这里有个小问题，由于头布局与GridView是一体的，如果GridView的宽度设置margin离左右有点距离，导致头布局离左右也会有点距离，怎么办呢，只能动态改变item的属性了，设置GridVIew宽度填充屏幕,界所在界面颜色背景为#e8ebed,条目根布局也是这个颜色，里面再多嵌套一层LinearLayout 

//为了让头布局宽度充满整个屏幕，而下面的其他条目左边离屏幕有一定的距离，右边的条目离右边有点距离
LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) holder.itemLayout.getLayoutParams();
if (position % 2 == 0) {
    params.leftMargin = mContext.getResources().getDimensionPixelSize(R.dimen.dp8);
    params.rightMargin = 0;
} else {
    params.leftMargin = 0;
    params.rightMargin = mContext.getResources().getDimensionPixelSize(R.dimen.dp8);
}
holder.itemLayout.setLayoutParams(params);

这里在Adapter中动态改变它的属性就可以了