我搜索了网络，除了课程的源代码之外找不到任何东西。我还是初学者，我并不完全明白应该如何实施这个课程
有人可以为我提供这样一个类的编码实现，比如两个标题，4个标题按页眉，一个顶部标题（网格视图上方），一个底部页脚（网格视图下方），以及演示如何实现可过滤？ （以视图中的文字说）
非常感谢
答案 0 :(得分：2)
package com.paging.gridview;
import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.GridView;
import android.widget.ListAdapter;
import java.util.ArrayList;
public class HeaderGridView extends GridView {
private ListAdapter mAdapter;
private Context mContext;
/**
* Should be used by subclasses to listen to changes in the dataset
*/
// AdapterDataSetObserver mDataSetObserver;
public HeaderGridView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public HeaderGridView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public HeaderGridView(Context context) {
super(context);
init(context);
}
private void init(Context context){
mContext = context;
// super.setOnScrollListener(this);
}
/**
* A class that represents a fixed view in a list, for example a header at the top
* or a footer at the bottom.
*/
private ArrayList<FixedViewInfo> mHeaderViewInfos = new ArrayList<FixedViewInfo>();
private ArrayList<FixedViewInfo> mFooterViewInfos = new ArrayList<FixedViewInfo>();
private void notifiyChanged(){
this.requestLayout();
this.invalidate();
}
/**
* Add a fixed view to appear at the top of the list. If this method 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: When first introduced, this method could only be called before
* setting the adapter with {@link #setAdapter(ListAdapter)}. Starting with
* {@link android.os.Build.VERSION_CODES#KITKAT}, this method may be
* called at any time. If the ListView's adapter does not extend
* {@link FooterViewGridAdapter}, it will be wrapped with a supporting
* instance of {@link android.widget.WrapperListAdapter}.
*
* @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) {
final 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);
// Wrap the adapter if it wasn't already wrapped.
if (mAdapter != null) {
if (!(mAdapter instanceof FooterViewGridAdapter)) {
mAdapter = new FooterViewGridAdapter(mHeaderViewInfos, mFooterViewInfos, mAdapter);
}
// Do not know if this really helps
notifiyChanged();
}
}
/**
* Add a fixed view to appear at the top of the list. 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: When first introduced, this method could only be called before
* setting the adapter with {@link #setAdapter(ListAdapter)}. Starting with
* {@link android.os.Build.VERSION_CODES#KITKAT}, this method may be
* called at any time. If the ListView's adapter does not extend
* {@link FooterViewGridAdapter}, it will be wrapped with a supporting
* instance of {@link android.widget.WrapperListAdapter}.
*
* @param v The view to add.
*/
public void addHeaderView(View v) {
addHeaderView(v, null, true);
}
public int getHeaderViewsCount() {
return mHeaderViewInfos.size();
}
/**
* Add a fixed view to appear at the bottom of the list. If addFooterView 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: When first introduced, this method could only be called before
* setting the adapter with {@link #setAdapter(ListAdapter)}. Starting with
* {@link android.os.Build.VERSION_CODES#KITKAT}, this method may be
* called at any time. If the ListView's adapter does not extend
* {@link FooterViewGridAdapter}, it will be wrapped with a supporting
* instance of {@link android.widget.WrapperListAdapter}.
*
* @param v The view to add.
* @param data Data to associate with this view
* @param isSelectable true if the footer view can be selected
*/
public void addFooterView(View v, Object data, boolean isSelectable) {
final FixedViewInfo info = new FixedViewInfo();
FrameLayout fl = new FullWidthFixedViewLayout(getContext());
fl.addView(v);
info.view = v;
info.viewContainer = fl;
info.data = data;
info.isSelectable = isSelectable;
mFooterViewInfos.add(info);
// Wrap the adapter if it wasn't already wrapped.
if (mAdapter != null) {
if (!(mAdapter instanceof FooterViewGridAdapter)) {
mAdapter = new FooterViewGridAdapter(mHeaderViewInfos, mFooterViewInfos, mAdapter);
}
// Do not know if this really helps
notifiyChanged();
}
}
/**
* Add a fixed view to appear at the bottom of the list. If addFooterView 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: When first introduced, this method could only be called before
* setting the adapter with {@link #setAdapter(ListAdapter)}. Starting with
* {@link android.os.Build.VERSION_CODES#KITKAT}, this method may be
* called at any time. If the ListView's adapter does not extend
* {@link FooterViewGridAdapter}, it will be wrapped with a supporting
* instance of {@link android.widget.WrapperListAdapter}.
*
* @param v The view to add.
*/
public void addFooterView(View v) {
addFooterView(v, null, true);
}
public int getFooterViewsCount() {
return mFooterViewInfos.size();
}
/**
* Removes a previously-added footer view.
*
* @param v The view to remove
* @return
* true if the view was removed, false if the view was not a footer view
*/
public boolean removeFooterView(View v) {
if (mFooterViewInfos.size() > 0) {
boolean result = false;
if (mAdapter != null && ((FooterViewGridAdapter) mAdapter).removeFooter(v)) {
notifiyChanged();
result = true;
}
removeFixedViewInfo(v, mFooterViewInfos);
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) {
this.mAdapter = adapter;
if (mHeaderViewInfos.size() > 0|| mFooterViewInfos.size() > 0) {
mAdapter = new FooterViewGridAdapter(mHeaderViewInfos, mFooterViewInfos, adapter);
} else {
mAdapter = adapter;
}
super.setAdapter(adapter);
super.setAdapter(this.mAdapter);
requestLayout();
}
@Override
public ListAdapter getAdapter() {
return this.mAdapter;
}
public class FixedViewInfo {
public android.view.View view;
public ViewGroup viewContainer;
public java.lang.Object data;
public boolean isSelectable;
}
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);
}
}
}