ListView Adapter优化 实例

    private String[] mArrData;
    private ListView listView;
    private AsyncImageLoader asyncImageLoader;
    private final LayoutInflater inflater;

    public listviewAdapterDemo1(String[] mArrData, Context mContext, ListView listView) {
        this.mArrData = mArrData;
        this.listView = listView;
        asyncImageLoader = new AsyncImageLoader();
        inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return this.mArrData.length;
    }

    @Override
    public Object getItem(int arg0) {
        return mArrData[arg0];
    }

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

    /***
     * 1.控件对象内存为一个
     * 2.view对象只会创建可视对象次数（有的是8次）根据屏幕可视listview的数量而定，在加载超过可视postion数据时不会重新创建
     *   但是需要每次重新加载数据
     *  
     *   从节省内存的角度出发，这种更合理，毕竟加载数据不需要占用内存
     */
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        ViewHolder viewholder;
        Log.d("dd", "Position:" + position+"------");
        if (convertView == null) {
            Log.d("dd", "Position:" + position);
            convertView = inflater.inflate(R.layout.list_item_icon_text, null);
            viewholder = new ViewHolder();
            viewholder.icon = (ImageView) convertView.findViewById(R.id.icon);
            viewholder.text = (TextView) convertView.findViewById(R.id.text);

            convertView.setTag(viewholder);
        } else {
            viewholder = (ViewHolder) convertView.getTag();
        }

        viewholder.text.setText(mArrData[position]);
        // Load the image and set it on the ImageView
        String imageUrl = "";
        viewholder.icon.setTag(imageUrl);
        Drawable cachedImage = asyncImageLoader.loadDrawable(imageUrl, new ImageCallback() {

            public void imageLoaded(Drawable imageDrawable, String imageUrl) {
                ImageView imageViewByTag = (ImageView) listView.findViewWithTag(imageUrl);
                if (imageViewByTag != null) {
                    imageViewByTag.setImageDrawable(imageDrawable);
                }
            }
        });
        if (cachedImage != null)//说明是从缓存池中得到
            viewholder.icon.setImageDrawable(cachedImage);

        return convertView;
    }

    static class ViewHolder {
        ImageView icon;
        TextView text;
    }
}
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在listview中的getview方法中也可以这样用这个方法：

    private String[] mArrData;
    private ListView listView;
    private AsyncImageLoader asyncImageLoader;
    private final LayoutInflater inflater;
    private Map<Integer, View> viewMap = new HashMap<Integer, View>();

    public listviewAdapterDemo2(String[] mArrData, Context mContext, ListView listView) {
        this.mArrData = mArrData;
        this.listView = listView;
        asyncImageLoader = new AsyncImageLoader();
        inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return this.mArrData.length;
    }

    @Override
    public Object getItem(int arg0) {
        return mArrData[arg0];
    }

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

    /**
     * 1.控件对象内存为一个
     * 2.每一个postion对应一个view，且不管前进后退，每个postion数据只加载一次　　　* 但是从节省内容的角度出发，方案一更节省内存
     */
    @Override
    public View getView(int position, View convertVi