Android GridView增加HeaderView和FooterView的实现
做的项目中遇到一个问题，需要实现一个页面
页面的上面是一个自定义的View和GridView，当向下滚动屏幕的时候，需要确保两者一起滑动
之前没遇到过这种情况，直接按照心中的想法实现了，发现遇到问题了
“GridView只显示一行记录”
网上搜索之后发现很多人遇到过，也多贴出解决的方法
大概实现的方法有几种：
- 重载GridView的onMeasure()方法
- 使用google提供的HeaderGridView类 -- 主要实现的原理是将HeaderView当作其中一个Item来显示，同时也需要考虑高度的不同
- 借助开源项目，很多个，比如android-GridViewWithHeaderAndFooter
我这里使用的是HeaderGridView类，比较简单
//初始化HeaderView LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); headerView = inflater.inflate(R.layout.activity_page_header, null); gridView = (HeaderGridView) findViewById(R.id.gridview); gridView.addHeaderView(headerView); // 他需要在setAdapter()之前 gridView.setAdapter(twoAdapter);
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:background="@color/white" android:orientation="vertical"> <com.dudress.dress.detail.HeaderGridView android:id="@+id/gridview" android:layout_width="match_parent" android:layout_height="match_parent" android:horizontalSpacing="6dp" android:numColumns="2" android:background="@color/gray_dc" android:verticalSpacing="10dp"></com.dudress.dress.detail.HeaderGridView> </LinearLayout>
附上HeaderGridView类的源码，复制回去直接使用
package com.dudress.dress.detail; /** * Created by zhou on 16-4-6. */ 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.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)} */ 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; /** <code>true</code> if the fixed view should be selectable in the grid */ public boolean isSelectable; } private ArrayList<FixedViewInfo> mHeaderViewInfos = new ArrayList<FixedViewInfo>(); 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. * <p> * 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. * <p> * 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<FixedViewInfo> 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. *<p>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<FixedViewInfo> mHeaderViewInfos; boolean mAreAllFixedViewsSelectable; private final boolean mIsFilterable; public HeaderViewGridAdapter(ArrayList<FixedViewInfo> 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<FixedViewInfo> 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(); } } }