节目单左右滑动不好用，怎么办
先从动画开始看起
参考资料：
1. Android Animations - Tutorial
http://www.vogella.com/articles/AndroidAnimation/article.html
2. Is there any useful Android Animation Tutorial for beginners?
3. Android Fragments and animation
http://stackoverflow.com/questions/4817900/android-fragments-and-animation
通过ListView实现一个二级树
在频道列表的需要中有频道类别和频道两种数据。频道是频道类别的下级数据。每个频道类别可以保含多个频道。在界面上频道类别和频道用两种布局来表现。频道类别只有名称和箭头，频道类别展开时，箭头向下，频道类别收起来时，箭头向右。频道中的数据项比较多比如名称、图标、状态等。
新建TvChannelAdapter继承BaseAdapter。在构造方法中定义两个参数context表示上下文，categorys表示数据，然后将在界面上可见的频道类别和频道两类数据取出来保存在itemList中。itemList表示adapter中的数据。
先看TvChannelAdapter中几个比较简单点的方法
private Context context;
private List<ChannelGroupData> categorys;
private List<Object> itemList;
private String selectChannelId = "000";
public TvChannelAdapter(Context context, List<ChannelGroupData> categorys) {
this.context = context;
this.categorys = categorys;
this.initializeItemList();
}
private void initializeItemList() {
itemList = new ArrayList<Object>();
for (int i = 0; i < categorys.size(); i++) {
ChannelGroupData category = categorys.get(i);
itemList.add(category);
if (category.isInExpanding())
itemList.addAll(category.getData());
}
}
@Override
public void notifyDataSetChanged() {
if (itemList != null) {
itemList.clear();
itemList = null;
}
initializeItemList();
super.notifyDataSetChanged();
}
@Override
public int getCount() {
return itemList.size();
}
@Override
public Object getItem(int position) {
return itemList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}再来看TvChannelAdapter中很关键的方法getView。由于listView中要表现两种类型的数据，所以在getView方法中就要构造出两种类型的view。其中频道类别view用item_tvchannel_category.xml来构建，频道view用item_tvchannel_child.xml来构建。getView方法中返回的每个view的都来自itemList中的数据，view和数据用position关联对应。
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder = new ViewHolder();
if (itemList.get(position) instanceof ChannelItemData) {
convertView = LayoutInflater.from(context).inflate(R.layout.item_tvchannel_child, null);
initializeItemViewHolder(viewHolder, (ChannelItemData) itemList.get(position), convertView);
} else {
convertView = LayoutInflater.from(context).inflate(R.layout.item_tvchannel_category, null);
initializeCategoryViewHolder(viewHolder, position, convertView);
}
return convertView;
}在getView方法中有个Viewholder。它的定义如下，包含convertView中所有用到的view项。
private static class ViewHolder {
AsyncImageView channelIcon;
TextView channelName;
TextView channelStatus;
TextView categoryName;
ImageView btnExpand;
}当数据类型是频道类别时，调用initxxx来构建频道类别view中的内容。
频道类别点击时可以展开或者收起下级的频道。
private void initializeCategoryViewHolder(final ViewHolder viewHolder, final int position, View convertView) {
final ChannelGroupData category = (ChannelGroupData) itemList.get(position);
viewHolder.categoryName = (TextView) convertView.findViewById(R.id.channelGroupTitleName);
viewHolder.btnExpand = (ImageView) convertView.findViewById(R.id.btnExpand);
viewHolder.categoryName.setText(category.getName());
viewHolder.btnExpand.setImageResource(category.isInExpanding() ? R.drawable.channel_expand_btn
: R.drawable.channel_shrink_btn);
viewHolder.btnExpand.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if(category.isInExpanding()) {
category.setInExpanding(false);
} else {
category.setInExpanding(true);
shrinkOtherGroupTitle(position);
}
notifyDataSetChanged();
}
});
convertView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
viewHolder.btnExpand.performClick();
}
});
}
public void shrinkOtherGroupTitle(int position) {
for (int i = 0; i < itemList.size(); i++) {
if (itemList.get(i) instanceof ChannelGroupData) {
((ChannelGroupData) itemList.get(i)).setInExpanding(i == position);
}
}
}当数据类型表现为频道时，频道view也有个点击事件，点击时记下频道的id，然后调用notifyDataSetChanged方法，将点击的那个频道设置背景颜色表示选中状态。
private void initializeItemViewHolder(ViewHolder viewHolder, final ChannelItemData item, View convertView) {
String hint = context.getResources().getString(R.string.live_play);
String liveName = item.getLiveEpg().getName();
if (TextUtils.isEmpty(liveName) || liveName.equalsIgnoreCase("null"))
liveName = "（未知）";
viewHolder.channelIcon = (AsyncImageView) convertView.findViewById(R.id.channelIcon);
viewHolder.channelName = (TextView) convertView.findViewById(R.id.channelName);
viewHolder.channelStatus = (TextView) convertView.findViewById(R.id.channelStatus);
viewHolder.channelIcon.setCleartrue);
viewHolder.channelIcon.setUrl(item.getIcon());
viewHolder.channelName.setText(item.getName());
viewHolder.channelStatus.setVisibility(View.VISIBLE);
viewHolder.channelStatus.setText(hint + liveName);
if(selectChannelId.equals(item.getChannelId()))
convertView.setBackgroundColor(context.getResources().getColor(R.color.lightblue));
else
convertView.setBackgroundColor(context.getResources().getColor(R.color.default_backgroud_color));
convertView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(item.getCategoryId() != null) {
selectChannelId = item.getChannelId();
notifyDataSetChanged();
}
}
});
}
