Android Scrollview+Listview 实现不同条目点赞并计数功能及原理分析（3）

来源：互联网发布：大非农数据是什么意思编辑：程序博客网时间：2024/06/02 21:52

过了有点久，还好上次把代码发上去了，不会影响。现在我们来解决最后一个问题

点赞后计数改变

这个问题难在哪里呢，就是我们需要在自定义的adapter中设置每个item长什么样子，每个子控件的clickListener也需要在这里设置，但是有时候点击事件需要改变外层的页面属性。比如我在item中有一个button，点击它，整个屏幕就暗了，显然需要在外界得到这个button的click事件。解决这个问题有几种方法，下面一个个说；

使用回调函数（也是代码中使用的）

在adapter中设置一个interface，然后在click中调用interface的方法，外层的代码需要实现这个interface，这样实际button的click的具体实现方法就在外层去做了。
item实现代码：

public class SampleItem extends BaseAdapter implements View.OnClickListener{    private Context context;    private Callback callback;    private List<ItemMsg> listMsg;    public List<ItemMsg> getListMsg() {        return listMsg;    }    public void setListMsg(List<ItemMsg> listMsg) {        this.listMsg = listMsg;    }    public SampleItem(Context context,Callback callback,List<ItemMsg> list){        this.context = context;        this.callback = callback;        this.listMsg = list;    }    public interface Callback{        public void myClick(View view);    }    @Override    public int getCount() {        return listMsg.size();    }    @Override    public Object getItem(int i) {        return listMsg.get(i);    }    @Override    public long getItemId(int i) {        return i;    }    @Override    public View getView(int i, View view, ViewGroup viewGroup) {        ViewHolder viewHolder= null;        if (view == null){            view = LayoutInflater.from(context).inflate(R.layout.item,null);            viewHolder = new ViewHolder();            viewHolder.up = (ImageButton)view.findViewById(R.id.up);            viewHolder.down = (ImageButton)view.findViewById(R.id.down);            viewHolder.itemMsg = (TextView)view.findViewById(R.id.item_text);            view.setTag(viewHolder);        }else{            viewHolder = (ViewHolder)view.getTag();        }        viewHolder.up.setOnClickListener(this);        viewHolder.up.setTag(i);        viewHolder.down.setOnClickListener(this);        viewHolder.down.setTag(i);        viewHolder.itemMsg.setText(Integer.toString(listMsg.get(i).getI()));        return view;    }    public class ViewHolder{        private ImageButton up,down;        private TextView itemMsg;    }    @Override    public void onClick(View view) {        callback.myClick(view);    }}

外层调用代码：

public class MainActivity extends Activity implements SampleItem.Callback{    private ListView listView;    private SampleItem sampleItemAdapter;    private Context context;    @Override    protected void onCreate(Bundle savedInstanceState) {        ...    }    @Override    public void myClick(View view) {        switch(view.getId()){            case R.id.up:                ItemMsg itemMsgUp = sampleItemAdapter.getListMsg().get((Integer)view.getTag());                itemMsgUp.increase();                sampleItemAdapter.notifyDataSetChanged();                break;            case R.id.down:                ItemMsg itemMsgDown = sampleItemAdapter.getListMsg().get((Integer)view.getTag());                itemMsgDown.decrease();                sampleItemAdapter.notifyDataSetChanged();                break;        }    }}

2 传入handler，在每一次点击事件的时候发送一个msg，然后在外层拦截

这种方式就比较“Android”，但是并不是一个好方法，每一个点击事件都需要发送一个message，效率不高，也许有些场景会接受这种。
item代码：

public class SampleItem extends BaseAdapter implements View.OnClickListener{    public static final int UP = 1;    public static final int DOWN = 2;    private Context context;    private Callback callback;    private List<ItemMsg> listMsg;    private Handler handler;    public List<ItemMsg> getListMsg() {        return listMsg;    }    public void setListMsg(List<ItemMsg> listMsg) {        this.listMsg = listMsg;    }    public SampleItem(Context context,Callback callback,List<ItemMsg> list){        this.context = context;        this.callback = callback;        this.listMsg = list;    }    public SampleItem(Context context,List<ItemMsg> list,Handler handler){        this.context = context;        this.listMsg = list;        this.handler = handler;    }    public interface Callback{        public void myClick(View view);    }    @Override    public int getCount() {        return listMsg.size();    }    @Override    public Object getItem(int i) {        return listMsg.get(i);    }    @Override    public long getItemId(int i) {        return i;    }    @Override    public View getView(int i, View view, ViewGroup viewGroup) {        ViewHolder viewHolder= null;        if (view == null){            view = LayoutInflater.from(context).inflate(R.layout.item,null);            viewHolder = new ViewHolder();            viewHolder.up = (ImageButton)view.findViewById(R.id.up);            viewHolder.down = (ImageButton)view.findViewById(R.id.down);            viewHolder.itemMsg = (TextView)view.findViewById(R.id.item_text);            view.setTag(viewHolder);        }else{            viewHolder = (ViewHolder)view.getTag();        }        viewHolder.up.setOnClickListener(this);        viewHolder.up.setTag(i);        viewHolder.down.setOnClickListener(this);        viewHolder.down.setTag(i);        viewHolder.itemMsg.setText(Integer.toString(listMsg.get(i).getI()));        return view;    }    public class ViewHolder{        private ImageButton up,down;        private TextView itemMsg;    }    @Override    public void onClick(View view) {        //way 1//        callback.myClick(view);        //way 2        Message msg = new Message();        msg.arg1 = (Integer)view.getTag();        switch (view.getId()){            case R.id.up:                msg.what = UP;                handler.sendMessage(msg);                break;            case R.id.down:                msg.what = DOWN;                handler.sendMessage(msg);                break;        }    }}

外层代码：

Handler mHandler = new Handler(){            @Override            public void handleMessage(Message msg) {                switch (msg.what){                    case SampleItem.UP:                        ItemMsg itemMsgUp = sampleItemWithHandler.getListMsg().get(msg.arg1);                        itemMsgUp.increase();                        sampleItemWithHandler.notifyDataSetChanged();                        break;                    case SampleItem.DOWN:                        ItemMsg itemMsgDown = sampleItemWithHandler.getListMsg().get(msg.arg1);                        itemMsgDown.decrease();                        sampleItemWithHandler.notifyDataSetChanged();                        break;                }            }        };

这两种方法都是可以发到目的，时间不早了，再不回宿舍就关门了。。。
接下来在这个基础上加上一个下拉刷新，尽请期待~~~
新加了一种实现方式，代码地址：
http://download.csdn.net/detail/wsrspirit/9294389

1 0