2015/10/10
一不小心在看ListView优化的时候看到了Adapter的复用，发现万能的Adapter发现确实很好，节省多余的代码在项目中

两个网址
http://www.cnblogs.com/smyhvae/p/4477079.html 代码基本来自这里

https://github.com/JoanZapata/base-adapter-helper github上面的挺有名的 稍微看了一下这两个代码差不多

这个源码就是这样

public abstract class MyBaseAdapter<T> extends BaseAdapter {
private List<T> mDatas;
private Context mContext;
private LayoutInflater mLayoutInflater;
private int layoutId;
public MyBaseAdapter(List<T> mDatas, Context mContext, int layoutId) {
    this.mDatas = mDatas;
    this.mContext = mContext;
    this.mLayoutInflater = LayoutInflater.from(mContext);
    this.layoutId = layoutId;
}

@Override
public int getCount() {
    return mDatas.size();
}

@Override
public T getItem(int position) {
    return mDatas.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    //初始化ViewHolder,使用通用的ViewHolder，一样代码就搞定ViewHolder的初始化咯
    MyViewHolder holder = MyViewHolder.get(mContext, convertView, parent, layoutId, position);//layoutId就是单个item的布局
    convert(holder, getItem(position));
    return holder.getConvertView(); //这一行的代码要注意了
}
//将convert方法公布出去 子类实现
public abstract void convert(MyViewHolder holder, T t);
}


class MyViewHolder {
private SparseArray<View> mViews;
private int mPosition;
private View mCurrentView;
public MyViewHolder(Context context, ViewGroup parent, int layoutId, int position) {
    this.mPosition = position;
    this.mViews = new SparseArray<View>();
    mCurrentView = LayoutInflater.from(context).inflate(layoutId, parent, false);
    mCurrentView.setTag(this);
}

public static MyViewHolder get(Context context, View convertView, ViewGroup parent, int layoutId, int position) {
    if (convertView == null) {
        return new MyViewHolder(context, parent, layoutId, position);
    } else {
        MyViewHolder holder = (MyViewHolder) convertView.getTag();
        holder.mPosition = position; //ViewHolder是复用的，position更新一下
        return holder;
    }
}
    /*
   通过viewId获取控件
   */
    //使用的是泛型T,返回的是View的子类
    public <T extends View> T getView(int viewId) {
    View view = mViews.get(viewId);
    //复用
    if (view == null) {
        view = mCurrentView.findViewById(viewId);
        mViews.put(viewId, view);
    }
    return (T) view;
}
public View getConvertView() {
    return mCurrentView;
}
}

在Activity中

public class BaseAdapterActivity extends ActionBarActivity {
private android.widget.ListView lvshow;
private android.widget.GridView gvshow;
private android.widget.Button btlistview;
private android.widget.Button btgridview;
public List<String> lists=new ArrayList<String>();
private GridViewAdpater gridViewAdpater;
private ListViewAdpater listViewAdpater;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_base_adapter);
    this.btgridview = (Button) findViewById(R.id.bt_gridview);
    this.btlistview = (Button) findViewById(R.id.bt_listview);
    this.gvshow = (GridView) findViewById(R.id.gv_show);
    this.lvshow = (ListView) findViewById(R.id.lv_show);
    listViewAdpater=new ListViewAdpater(lists,this,R.layout.item_baseadapter_listview);

    lvshow.setAdapter(listViewAdpater);
    btlistview.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            gvshow.setVisibility(View.GONE);
            lvshow.setVisibility(View.VISIBLE);
            lists.clear();
            for(int i=0 ; i<200 ; i++) {
                lists.add("Daemon " + i);
            }
            listViewAdpater.notifyDataSetChanged();
        }
    });

    lists.clear();
    gridViewAdpater=new GridViewAdpater(lists,this,R.layout.item_baseadapter_listview);
    gvshow.setAdapter(gridViewAdpater);
    btgridview.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            lvshow.setVisibility(View.GONE);
            gvshow.setVisibility(View.VISIBLE);
            lists.clear();
            for(int i=0 ; i<200 ; i++){
                lists.add("Daemon "+i);
            }
            gridViewAdpater.notifyDataSetChanged();
        }
    });
}

class ListViewAdpater extends MyBaseAdapter<String>{
public ListViewAdpater(List<String> mDatas, Context mContext, int layoutId) {
    super(mDatas, mContext, layoutId);
}

@Override
public void convert(MyViewHolder holder, String s) {
    ((TextView)holder.getView(R.id.tv_show)).setText(s);
}
}

class GridViewAdpater extends MyBaseAdapter<String>{
public GridViewAdpater(List<String> mDatas, Context mContext, int layoutId) {
    super(mDatas, mContext, layoutId);
}

@Override
public void convert(MyViewHolder holder, String s) {
    ((TextView)holder.getView(R.id.tv_show)).setText(s);
}
}

这样做到了Adapter的复用写来节省了很多代码，不用在每次都新建继承BaseAdpater写很多重复的代码了

效果图

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