通用于ListView的Adapter

在开发的时候，经常会用到ListView，用到ListView就要写对应的Adapter，还要写对应的ViewHolder，那么一整个项目下来，基本上都花了很多时间来写这些东西，所以，上网找了下，学着用别人写的一些通用的Adapter和ViewHolder，高度封装，扩展性强。

1.先写MyViewHolder：

package com.hvgroup.vgopapp.ui.widget;

import android.content.Context;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


public class MyViewHolder {
    private final SparseArray<View> mViews;
    private int mPosition;
    private View mConvertView;

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

    /**
     * 拿到一个ViewHolder对象
     *
     * @param context
     * @param convertView
     * @param parent
     * @param layoutId
     * @param position
     * @return
     */
    public static MyViewHolder get(Context context, View convertView,
                                   ViewGroup parent, int layoutId, int position) {
        if (convertView == null) {
            return new MyViewHolder(context, parent, layoutId, position);
        }
        return (MyViewHolder) convertView.getTag();
    }

    public View getConvertView() {
        return mConvertView;
    }

    /**
     * 通过控件的Id获取对于的控件，如果没有则加入views
     *
     * @param viewId
     * @return
     */
    public <T extends View> T getView(int viewId) {
        View view = mViews.get(viewId);
        if (view == null) {
            view = mConvertView.findViewById(viewId);
            mViews.put(viewId, view);
        }
        return (T) view;
    }

    /**
     * 为TextView设置字符串
     *
     * @param viewId
     * @param text
     * @return
     */
    public MyViewHolder setText(int viewId, String text) {
        TextView view = getView(viewId);
        view.setText(text);
        return this;
    }

    /**
     * 为控件设置点击监听
     *
     * @param viewId
     * @param listener
     * @return
     */

    public MyViewHolder setClickListener(int viewId , View.OnClickListener listener)
    {
        View view = getView(viewId);
        view.setOnClickListener(listener);
        return this;
    }

    public int getPosition()
    {
        return mPosition;
    }
}

这里用来存放每个item的View的是一个SparseArray的对象。SparseArray是一个Map来的，存放键值对，不过键是int类型，更加高效。MyViewHolder里面可以按需要加入一些设置控件常用的方法，如setText，setClickListener等。

2.再写CommonAdapter：

package com.hvgroup.vgopapp.ui.widget;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

import java.util.List;


public abstract class CommonAdapter<T> extends BaseAdapter
{
    protected LayoutInflater mInflater;
    protected Context mContext;
    protected List<T> mDatas;
    protected final int mItemLayoutId;

    public CommonAdapter(Context context, List<T> mDatas, int itemLayoutId)
    {
        this.mContext = context;
        this.mInflater = LayoutInflater.from(mContext);
        this.mDatas = mDatas;
        this.mItemLayoutId = itemLayoutId;
    }

    @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)
    {
        final MyViewHolder viewHolder = getViewHolder(position, convertView,
                parent);
        convert(viewHolder, getItem(position));
        viewHolder.getConvertView().setBackgroundColor(position%2 == 0 ? 0xFF232939 : 0xFF2A3141);
        return viewHolder.getConvertView();

    }

    public abstract void convert(MyViewHolder helper, T item);

    private MyViewHolder getViewHolder(int position, View convertView,
                                       ViewGroup parent)
    {
        return MyViewHolder.get(mContext, convertView, parent, mItemLayoutId,
                position);
    }

}

以后用这个CommonAdapter只需要new一个对象，并且重写convert方法就可以了，会方便很多。

3.MainActivity里面就只要这么写：

mCommonAdapter = new CommonAdapter<PersonInfo>(getActivity(),mDatas, R.layout.myfragment_listivew_item) {
<span style="white-space:pre">	</span>@Override
<span style="white-space:pre">	</span>public void convert(MyViewHolder helper, PersonInfo item) {
<span style="white-space:pre">		</span>helper.setText(R.id.name,item.name);
<span style="white-space:pre">	</span>}
};
mListView.setAdapter(mCommonAdapter);