有关ListView与Button的共存问题

时间:2021-10-10 17:48:51


ListView 和 其它能触发点击事件的widget无法一起正常工作的原因是加入其它widget后,ListView的itemclick事件将无法触发,被其它widget的click事件屏蔽。
 
•首先,说明一下,ListView中每一行包括以下三项:
 
   一个ImageView, 一个TextView,一个ImageButton,依次排开。
 
以下是layout的内容,分为两部分:
•res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="fill_parent"
    android:padding="10dip" android:orientation="vertical">

    <ListView android:id="@id/android:list" android:layout_width="fill_parent"
        android:layout_height="fill_parent" />
</LinearLayout>
 


因为继承了ListActivity,所以ListView 的id设置为"@id/android:list"是必须的

•res/layout/lvitem.xml
注意:

在<RelativeLayout>中

android:descendantFocusability="blocksDescendants"

和<ImageButton>中

android:focusable="false"

这两项的设置很关键,如果不设置,将导致ListView的ItemClick事件将无法触发,该事件被ImageButton的click事件屏蔽了。


<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:padding="5dip"
  android:descendantFocusability="blocksDescendants" >
 
  <ImageView
      android:id="@+id/ItemImage"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:padding="5dip"
  />
 
 
  <!--
      把按钮背景设置为透明:     android:background="#00000000"
      把按钮背景设置为半透明:     android:background="#e0000000"
      -->
  <ImageButton
     android:id="@+id/ItemCloseWin"
     
     android:layout_alignParentRight="true"
     android:layout_alignTop="@+id/ItemWinName"
      android:layout_alignBottom="@+id/ItemWinName"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
     
      android:background="#e0000000"
      android:gravity="left|center_vertical"
      android:focusable="false"
      android:src="@android:drawable/ic_menu_close_clear_cancel"
  />
 
  <TextView
      android:id="@+id/ItemWinName"
     
      android:layout_toRightOf="@+id/ItemImage"
      android:layout_toLeftOf="@+id/ItemCloseWin"
      android:layout_alignTop="@+id/ItemImage"
      android:layout_alignBottom="@+id/ItemImage"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
     
      android:gravity="left|center_vertical"
      android:textSize="20dip"
      android:text="title"
  />
   
  
</RelativeLayout>
 

•接下来,我们看看继承ListActivity的实现
在lvWithButtonExt中,为了能处理ImageButton的click事件,我继承了BaseAdapter类,并重新实现了getView()接口,在其中加入了Button的clicklistener,详见lvButtonAdapter类的实现。

public class lvWithButtonExt extends ListActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // 关联Layout中的ListView
        ListView vncListView = (ListView)findViewById(android.R.id.list);
       
        // 生成动态数组,加入数据
        ArrayList<HashMap<String, Object>> remoteWindowItem = new ArrayList<HashMap<String, Object>>();
        for(int i=0;i<10;i++)
        {
            HashMap<String, Object> map = new HashMap<String, Object>();
            map.put("ItemImage", R.drawable.firefox);//图像资源的ID
            map.put("ItemWinName", "Window ID "+i);
            map.put("ItemCloseWin", android.R.drawable.ic_menu_close_clear_cancel);
            remoteWindowItem.add(map);
        }
       
      // 生成适配器的Item和动态数组对应的元素
        lvButtonAdapter listItemAdapter = new lvButtonAdapter(
            this,
            remoteWindowItem,//数据源
            R.layout.lvitem,//ListItem的XML实现

            //动态数组与ImageItem对应的子项
            new String[] {"ItemImage","ItemWinName", "ItemCloseWin"},
            //ImageItem的XML文件里面的一个ImageView,两个TextView ID
            new int[] {R.id.ItemImage,R.id.ItemWinName,R.id.ItemCloseWin}
        );
       
        vncListView.setAdapter(listItemAdapter);
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        // TODO Auto-generated method stub
        super.onListItemClick(l, v, position, id);
        l.getItemAtPosition(position);
    }
}
 

•接下来,我们看看lvButtonAdapter的实现
为了响应按钮的点击事件,首先要记录按钮的位置,然后为按钮设置clicklistener。

在重新实现的getView()接口中,我使用了lvButtonListener监听类,在构造函数中,记录行号,以便在OnClick接口中能准确的定位按钮所在的位置,进而对相应的行进行处理。

public class lvButtonAdapter extends BaseAdapter {
    private class buttonViewHolder {
        ImageView appIcon;
        TextView appName;
        ImageButton buttonClose;
    }
   
    private ArrayList<HashMap<String, Object>> mAppList;
    private LayoutInflater mInflater;
    private Context mContext;
    private String[] keyString;
    private int[] valueViewID;
    private buttonViewHolder holder;
   
    public lvButtonAdapter(Context c, ArrayList<HashMap<String, Object>> appList, int resource,
            String[] from, int[] to) {
        mAppList = appList;
        mContext = c;
        mInflater = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        keyString = new String[from.length];
        valueViewID = new int[to.length];
        System.arraycopy(from, 0, keyString, 0, from.length);
        System.arraycopy(to, 0, valueViewID, 0, to.length);
    }
   
    @Override
    public int getCount() {
        return mAppList.size();
    }

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

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

    public void removeItem(int position){
        mAppList.remove(position);
        this.notifyDataSetChanged();
    }
   
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView != null) {
            holder = (buttonViewHolder) convertView.getTag();
        } else {
            convertView = mInflater.inflate(R.layout.lvitem, null);
            holder = new buttonViewHolder();
            holder.appIcon = (ImageView)convertView.findViewById(valueViewID[0]);
            holder.appName = (TextView)convertView.findViewById(valueViewID[1]);
            holder.buttonClose = (ImageButton)convertView.findViewById(valueViewID[2]);
            convertView.setTag(holder);
        }
       
        HashMap<String, Object> appInfo = mAppList.get(position);
        if (appInfo != null) {
            String aname = (String) appInfo.get(keyString[1]);
            int mid = (Integer)appInfo.get(keyString[0]);
            int bid = (Integer)appInfo.get(keyString[2]);
            holder.appName.setText(aname);
            holder.appIcon.setImageDrawable(holder.appIcon.getResources().getDrawable(mid));
            holder.buttonClose.setImageDrawable(holder.buttonClose.getResources().getDrawable(bid));
            holder.buttonClose.setOnClickListener(new lvButtonListener(position));
        }       
        return convertView;
    }

    class lvButtonListener implements OnClickListener {
        private int position;

        lvButtonListener(int pos) {
            position = pos;
        }
       
        @Override
        public void onClick(View v) {
            int vid=v.getId();
            if (vid == holder.buttonClose.getId())
                removeItem(position);
        }
    }
}
 


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