实现这个功能一般有两种思路,一种思路是使用ScrollView+GridView,第二种思路是使用ListView来实现GridView的效果。
第一种思路的具体实现是把HeaderView和GridView都放到ScrollView里面,这里要解决的问题是ScrollView和GridView滑动手势的冲突问题,解决办法是让GridView充满ScrollView,不让GridView滑动而只让ScrollView滑动。具题做法是重载GridView的onMeasure()方法。
- public class MyGridView extends GridView {
- public MyGridView(Context context, AttributeSet attrs) {
- super(context, attrs);
- }
-
- public MyGridView(Context context) {
- super(context);
- }
-
- public MyGridView(Context context, AttributeSet attrs, int defStyle) {
- super(context, attrs, defStyle);
- }
-
- @Override
- public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
-
- int expandSpec = MeasureSpec.makeMeasureSpec(
- Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST);
- super.onMeasure(widthMeasureSpec, expandSpec);
- }
- }
这种方法的不足是GridView中的View没有复用,如果内容较多将比较消耗内存。
第二种思路的具体实现是使用ListView的addHeaderView()来添加HeaderView,而ListView的每一行都放一个LinearLayout来保存一行的item,这里要注意的是item的个数和ListView行数的关系。
后来在StackOverFlow上又看到了第三中方法。原来Google已经用GridView实现了,而且很巧妙,下面把代码贴出来
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- package com.android.photos.views;
- 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;
-
-
-
-
-
- public class HeaderGridView extends GridView {
- private static final String TAG = "HeaderGridView";
-
-
-
-
- private static class FixedViewInfo {
-
- public View view;
- public ViewGroup viewContainer;
-
- public Object data;
-
- 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) {
-
- }
-
-
-
-
-
-
-
-
-
-
-
-
- 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);
-
-
- if (adapter != null) {
- ((HeaderViewGridAdapter) adapter).notifyDataSetChanged();
- }
- }
-
-
-
-
-
-
-
-
-
-
- public void addHeaderView(View v) {
- addHeaderView(v, null, true);
- }
- public int getHeaderViewCount() {
- return mHeaderViewInfos.size();
- }
-
-
-
-
-
-
-
- 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);
- }
- }
-
-
-
-
-
-
-
- private static class HeaderViewGridAdapter implements WrapperListAdapter, Filterable {
-
-
- private final DataSetObservable mDataSetObservable = new DataSetObservable();
- private final ListAdapter mAdapter;
- private int mNumColumns = 1;
-
- 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) {
-
- int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
- if (position < numHeadersAndPlaceholders) {
- return (position % mNumColumns == 0)
- && mHeaderViewInfos.get(position / mNumColumns).isSelectable;
- }
-
- 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) {
-
- int numHeadersAndPlaceholders = getHeadersCount() * mNumColumns;
- if (position < numHeadersAndPlaceholders) {
- if (position % mNumColumns == 0) {
- return mHeaderViewInfos.get(position / mNumColumns).data;
- }
- return null;
- }
-
- 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) {
-
- 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());
- }
-
-
- convertView.setVisibility(View.INVISIBLE);
- convertView.setMinimumHeight(headerViewContainer.getHeight());
- return convertView;
- }
- }
-
- 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)) {
-
- 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();
- }
- }
- }
代码地址: https://github.com/liaohuqiu/android-GridViewWithHeaderAndFooter