android多种布局的列表实现

  最近有一个列表效果,需要一个列表有多种布局,最终效果如下:

android多种布局的列表实现

  

  这个我也问了同事以及开发群里的朋友,居然都没得到最优的实现方式的回答,看来这种复杂列表的需求还是比较少的,我自己也走了一些弯路,把我几个实现的方式整理下,希望对于还不了解的朋友有所帮助。

实现方式1:(每次getView时重新inflate itemView,convertView没有复用,性能低,运行没问题)

private class MyAdapter extends BaseAdapter{

        private List<Object> datas = Collections.EMPTY_LIST;

        public void setDatas(List<Object> datas) {
if(datas == null){
datas = Collections.EMPTY_LIST;
}
this.datas = datas;
notifyDataSetChanged();
} @Override
public int getCount() {
return datas.size();
} @Override
public Object getItem(int position) {
return datas.get(position);
} @Override
public long getItemId(int position) {
return 0;
} @Override
public View getView(int position, View convertView, ViewGroup parent) {
Object data = getItem(position); if(data instanceof Folder){
FolderViewHolder holder = null;
if(convertView != null && convertView.getTag() instanceof FolderViewHolder){
//View与数据类型一致
holder = (FolderViewHolder) convertView.getTag();
}else{
convertView = mInflater.inflate(R.layout.listitem1, null);
holder = new FolderViewHolder(convertView);
convertView.setTag(holder);
}
holder.setData((Folder)data);
}else{
FileViewHolder holder = null;
if(convertView != null && convertView.getTag() instanceof FileViewHolder){
//View与数据类型一致
holder = (FileViewHolder) convertView.getTag();
}else{
convertView = mInflater.inflate(R.layout.listitem2, null);
holder = new FileViewHolder(convertView);
convertView.setTag(holder);
}
holder.setData((File)data);
} return convertView;
}
} private class FolderViewHolder{
public TextView tvName; public FolderViewHolder(View itemView){
tvName = (TextView) itemView.findViewById(R.id.tvName);
} public void setData(Folder data) {
tvName.setText(data.name);
}
} private class FileViewHolder{
public TextView tvName; public FileViewHolder(View itemView){
tvName = (TextView) itemView.findViewById(R.id.tvName);
} public void setData(File data) {
tvName.setText(data.name);
}
}

实现方式2:(因为方式1不断inflate view,影响性能,于是考虑是否能尽可能重用已经inflate的view,于是添加了一个缓存,不过实际测试快速滑动或切换数据会显示异常,应该是AbsListView#RecycleBin缓存的原因,具体原因我后面理清了再添加,看别人的代码最痛苦了。。。)

private class MyAdapter extends BaseAdapter{

        private List<View> folderViewCaches = new ArrayList<View>(5);
private List<View> fileViewCaches = new ArrayList<View>(5); private List<Object> datas = Collections.EMPTY_LIST; public void setDatas(List<Object> datas) {
if(datas == null){
datas = Collections.EMPTY_LIST;
}
this.datas = datas;
notifyDataSetChanged();
} @Override
public int getCount() {
return datas.size();
} @Override
public Object getItem(int position) {
return datas.get(position);
} @Override
public long getItemId(int position) {
return 0;
} @Override
public View getView(int position, View convertView, ViewGroup parent) {
Object data = getItem(position); if(data instanceof Folder){
//文件夹,应该返回R.layout.listitem1对应的View
FolderViewHolder holder = null;
if(convertView != null && convertView.getTag() instanceof FolderViewHolder){
//View与数据类型一致
holder = (FolderViewHolder) convertView.getTag();
}else{
if(convertView != null){
//缓存到文件列表
fileViewCaches.add(convertView);
convertView = null;
} //从缓存里面取已从ListView移除的缓存(注释掉此部分代码显示正常)
if(!folderViewCaches.isEmpty()){
for(View cache : folderViewCaches){
if(cache.getParent() == null){
//缓存的View已从listView里面移除
convertView = cache;
holder = (FolderViewHolder) convertView.getTag();
folderViewCaches.remove(cache);
break;
}
}
} //还是没有,重新inflate
if(convertView == null){
convertView = mInflater.inflate(R.layout.listitem1, null);
holder = new FolderViewHolder(convertView);
convertView.setTag(holder);
}
} holder.setData((Folder) data); }else{
//文件,应该返回R.layout.listitem2对应的View
FileViewHolder holder = null;
if(convertView != null && convertView.getTag() instanceof FileViewHolder){
//View与数据类型一致
holder = (FileViewHolder) convertView.getTag();
}else{
if(convertView != null){
//缓存到文件夹列表
folderViewCaches.add(convertView);
convertView = null;
} //从缓存里面取已从ListView移除的缓存(注释掉此部分代码显示正常)
if(!fileViewCaches.isEmpty()){
for(View cache : fileViewCaches){
if(cache.getParent() == null){
//缓存的View已从listView里面移除
convertView = cache;
holder = (FileViewHolder) convertView.getTag();
fileViewCaches.remove(cache);
break;
}
}
} //还是没有,重新inflate
if(convertView == null){
convertView = mInflater.inflate(R.layout.listitem2, null);
holder = new FileViewHolder(convertView);
convertView.setTag(holder);
}
} holder.setData((File) data);
} return convertView;
}
}

实现方式3:(最佳实现,运行正常

后面仔细阅读ListView相关源码,才发现Adapter本身就支持不同的布局了,而且AbsListView#RecycleBin也支持不同类型的布局的缓存策略,RecycleBin.mViewTypeCount标示有多少种View类型。

我们需要做的就是重写Adapter的下面3个方法:

1.getViewTypeCount:

     /**
* 有多少种不同布局的View
*/
@Override
public int getViewTypeCount() {
return 2;
}

2.getItemViewType

        /**
* 相应position对应的View类型
*/
@Override
public int getItemViewType(int position) {
if(getItem(position) instanceof Folder){
return TYPE_FOLDER;
}else{
return TYPE_FILE;
}
}

3.getView,通过判断对应position的类型,返回相应类型的view:

     @Override
public View getView(int position, View convertView, ViewGroup parent) {
Object data = getItem(position); if(data instanceof Folder){
//TYPE_FOLDER,文件夹,应该返回R.layout.listitem1对应的View
FolderViewHolder holder = null;
if(convertView != null){
holder = (FolderViewHolder) convertView.getTag();
}else{
convertView = mInflater.inflate(R.layout.listitem1, null);
holder = new FolderViewHolder(convertView);
convertView.setTag(holder);
} holder.setData((Folder) data); }else{
//TYPE_FILE,文件,应该返回R.layout.listitem2对应的View
FileViewHolder holder = null;
if(convertView != null){
holder = (FileViewHolder) convertView.getTag();
}else{
convertView = mInflater.inflate(R.layout.listitem2, null);
holder = new FileViewHolder(convertView);
convertView.setTag(holder);
} holder.setData((File) data);
} return convertView;
}

此demo的github源码地址:

https://github.com/John-Chen/BlogSamples/tree/master/MultipleListTest

apk下载地址:

https://github.com/John-Chen/BlogSamples/blob/master/MultipleListTest/MultipleListTest.apk

如果写的有问题的地方,欢迎指教!

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