定义

适配器模式应用于数据类型转换的场景, 比如输入有无数种情况， 但是输出类型是统一的，我们可以通过Adapter返回一个统一的输出.
最典型的应用是ListView中使用的Adapter， 用户的item view各式各样， 但最终的输出都是属于view类型. ListView只需要知道getView返回的是一个View即可, 具体是什么view类型并不需要ListView关心.

代码

public class NewsAdapter extends BaseAdapter{
    private List<NewsBean> mNewsBeanList;
    private LayoutInflater mInflater;

    public NewsAdapter(Context context, List<NewsBean> list) {
        mNewsBeanList = list;
        mInflater = LayoutInflater.from(context);
    }

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

    @Override
    public Object getItem(int position) {
        return mNewsBeanList.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null) {
            viewHolder = new ViewHolder();
            convertView = mInflater.inflate(R.layout.item_layout, null);
            viewHolder.tvTitle = (TextView) convertView.findViewById(R.id.tv_title);
            viewHolder.tvDate = (TextView) convertView.findViewById(R.id.tv_date);
            viewHolder.tvContent = (TextView) convertView.findViewById(R.id.tv_content);
            convertView.setTag(viewHolder);

        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        viewHolder.tvTitle.setText(mNewsBeanList.get(position).title);
        viewHolder.tvDate.setText(mNewsBeanList.get(position).date);
        viewHolder.tvContent.setText(mNewsBeanList.get(position).content);

        return convertView;
    }

    class ViewHolder {
        public TextView tvTitle;
        public TextView tvDate;
        public TextView tvContent;
    }
}

给listView设置adapter

NewsAdapter newsAdapter = new NewsAdapter(GetJsonActivity.this, newsBeanList);
mListView.setAdapter(newsAdapter);

refer to:
https://github.com/AandK/volley_gson_demo/blob/master/src/GetJsonActivity.java
------DONE.-------