GridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL)不兼容低版本号系统解决方式

项目开发中须要使用GridView批处理操作，多项选择。

可是GridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL)不兼容低版本号。



找解决方式。查看android sdk提供的demo里介绍的GridView多项选择的方法

public class Grid3 extends Activity {

GridView mGrid;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

loadApps();

setContentView(R.layout.grid_1);
mGrid = (GridView) findViewById(R.id.myGrid);
mGrid.setAdapter(new AppsAdapter());
mGrid.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL);
mGrid.setMultiChoiceModeListener(new MultiChoiceModeListener());
}

private List<ResolveInfo> mApps;

private void loadApps() {
Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

mApps = getPackageManager().queryIntentActivities(mainIntent, 0);
}

public class AppsAdapter extends BaseAdapter {
public AppsAdapter() {
}

public View getView(int position, View convertView, ViewGroup parent) {
CheckableLayout l;
ImageView i;

if (convertView == null) {
i = new ImageView(Grid3.this);
i.setScaleType(ImageView.ScaleType.FIT_CENTER);
i.setLayoutParams(new ViewGroup.LayoutParams(50, 50));
l = new CheckableLayout(Grid3.this);
l.setLayoutParams(new GridView.LayoutParams(GridView.LayoutParams.WRAP_CONTENT,
GridView.LayoutParams.WRAP_CONTENT));
l.addView(i);
} else {
l = (CheckableLayout) convertView;
i = (ImageView) l.getChildAt(0);
}

ResolveInfo info = mApps.get(position);
i.setImageDrawable(info.activityInfo.loadIcon(getPackageManager()));

return l;
}

public final int getCount() {
return mApps.size();
}

public final Object getItem(int position) {
return mApps.get(position);
}

public final long getItemId(int position) {
return position;
}
}

public class CheckableLayout extends FrameLayout implements Checkable {
private boolean mChecked;

public CheckableLayout(Context context) {
super(context);
}

public void setChecked(boolean checked) {
mChecked = checked;
setBackgroundDrawable(checked ?
getResources().getDrawable(R.drawable.blue)
: null);
}

public boolean isChecked() {
return mChecked;
}

public void toggle() {
setChecked(!mChecked);
}

}

public class MultiChoiceModeListener implements GridView.MultiChoiceModeListener {
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
mode.setTitle("Select Items");
mode.setSubtitle("One item selected");
return true;
}

public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
return true;
}

public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
return true;
}

public void onDestroyActionMode(ActionMode mode) {
}

public void onItemCheckedStateChanged(ActionMode mode, int position, long id,
boolean checked) {
int selectCount = mGrid.getCheckedItemCount();
switch (selectCount) {
case 1:
mode.setSubtitle("One item selected");
break;
default:
mode.setSubtitle("" + selectCount + " items selected");
break;
}
}

}
}

实现了implements Checkable，然后能够设置GridView的多项选择，可是无法兼容低版本号

后来自己琢磨发现了解决兼容低版本号的方法。见代码

给GridView设置的Adapter

List<CodeGoodsListEntiy> goods = new ArrayList<CodeGoodsListEntiy>();
public class CollectionAdapter extends BaseAdapter{

@Override
public int getCount() {
// TODO Auto-generated method stub
return goods.size();
}

@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}

@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}

public void addDataList(List<CodeGoodsListEntiy> goodsList){
goods.addAll(goodsList);
}

public void removeAllList(){
goods.removeAll(goods);
}

public void removeData(CodeGoodsListEntiy entity){
goods.remove(entity);
}

public List<CodeGoodsListEntiy> getList(){
return goods;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
CheckableLayout layout = null;
CodeGoodsListEntiy good = goods.get(position);
if(convertView==null){
layout = new CheckableLayout();
convertView = inflater.inflate(R.layout.mycollection_griditem, null);
layout.imgviewlayout = (RelativeLayout) convertView.findViewById(R.id.imgviewlayout);
layout.iv = (ImageView) convertView.findViewById(R.id.iv);
layout.price = (TextView) convertView
.findViewById(R.id.price);
layout.title = (TextView) convertView.findViewById(R.id.title);
layout.sellnums = (TextView) convertView.findViewById(R.id.sells);
layout.item_selectbtn = (ImageView) convertView.findViewById(R.id.item_selectbtn);
layout.item_topview = (ImageView) convertView.findViewById(R.id.item_topview);
convertView.setTag(layout);
}else{
layout =  (CheckableLayout) convertView.getTag();
}

layout.price.setText("￥"+good.getSalePrice());
layout.title.setText(good.getTitle());
layout.sellnums.setText("月销量"+good.getSellNums());
layout.imgviewlayout.getLayoutParams().height = (SettingUtil.getDisplaywidthPixels() - SettingUtil
.dip2px(8)) / 2;
layout.iv.getLayoutParams().height = (SettingUtil.getDisplaywidthPixels() - SettingUtil
.dip2px(10)) / 2;
App.imageLoader.displayImage(good.getMainImg(), layout.iv, options, new SimpleImageLoadingListener());
if(editModel){
if(selecteditem.contains(position)){
layout.setChecked(true);
}else{
layout.setChecked(false);
}
}else{
layout.item_selectbtn.setVisibility(View.GONE);
layout.item_topview.setVisibility(View.GONE);
}
return convertView;
}

}

class CheckableLayout implements Checkable{

View convertView;
ImageView item_selectbtn;
ImageView item_topview;
ImageView iv;
TextView price;
TextView title;
TextView sellnums;
RelativeLayout imgviewlayout;

private boolean mChecked = false;

public CheckableLayout() {
// TODO Auto-generated constructor stub
}

@Override
public void setChecked(boolean checked) {
// TODO Auto-generated method stub
mChecked = checked;
if(item_topview!=null){
if(mChecked){
item_topview.setVisibility(View.GONE);
}else{
item_topview.setVisibility(View.VISIBLE);
}
}
if(item_selectbtn!=null){
if(mChecked){
item_selectbtn.setVisibility(View.VISIBLE);
}else{
item_selectbtn.setVisibility(View.GONE);
}
}
}

@Override
public boolean isChecked() {
// TODO Auto-generated method stub
return mChecked;
}

@Override
public void toggle() {
// TODO Auto-generated method stub
setChecked(!mChecked);
}

}

事实上这里class CheckableLayout implements Checkable类似于一般的Adapter里的ViewHolder的类一样的。

然后给GridView设置的ItemClickListener的方法

private OnItemClickListener onlvItemClick = new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
if(editModel){
CheckableLayout holder = (CheckableLayout) arg1.getTag();
if(selecteditem.contains(arg2)){
selecteditem.remove((Integer)arg2);
holder.setChecked(false);
}else{
selecteditem.add(arg2);
holder.setChecked(true);
}
}else{
ProDetailActivity.launch(MyCollectionActivity.this, goods
.get(arg2).getItemId());
}
}
};

事实上这里非常关键的就是通过传来的View得到那个ViewHolder类

CheckableLayout holder = (CheckableLayout) arg1.getTag();

或者用以下的代码

View view = gv.getChildAt(arg2 - gv.getFirstVisiblePosition());

CheckableLayout holder = (CheckableLayout) view.getTag();

这里一般的GridView或者ListView的BaseAdapter里复用了convertView的话，GridView.getChildCount的数量少于BaseAdapter.getCount数量。

仅仅会显示屏幕显示出的数量，这是BaseAdapter用ViewHolder复用convertView的特点。

所以假设要获取到单个itemview的话用上面的方法。

说到这里吧。非常多项目代码涉及到商业性，有问题能够交流。这样的方法须要注意细节就是了。

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