Android - 想要使用 cursorLoader 在列表视图中替换图标图像

Question

我有一个应用程序，它显示按姓氏排序的联系人列表视图，然后是名字。每个联系人旁边都有一个图像（图标）。有 3 种联系人我想显示 3 个不同的图像（客户/供应商/其他）我现在有一个默认图像，设置为客户。我想知道是否有一种方法可以使用下面显示的 cusorLoader 来动态交替图像，或者是否最好在我的 onResume 中添加一个涉及光标的方法。 （每次我需要显示图像时都会调用 onResume）。我相信 simpleCursorAdapter 只能将 textViews 作为参数，所以如果可能的话，也许复合 textview/image 会起作用。我的图标不存储在数据库中，只是在可绘制对象中。

提前感谢您的任何回复。

  @Override
  protected void onResume() {
   super.onResume();
   //Starts a new or restarts an existing Loader in this manager
   getLoaderManager().restartLoader(0, null, this);
  }

  /*
   * The fillData method binds the simpleCursorAadapter to the listView.
   */

  private void fillData() {

    String[] from = new String[] { ContactsDB.COLUMN_LAST_NAME, ContactsDB.COLUMN_FIRST_NAME };

    //The XML views that the data will be bound to:
    int[] to = new int[] {R.id.label2, R.id.label};

    getLoaderManager().initLoader(0, null, this);
    adapter = new SimpleCursorAdapter(this, R.layout.contact_row, null, from,
        to, 0);
    setListAdapter(adapter);
  }
  // Sort the names by last name, then by first name
  String orderBy = ContactsDB.COLUMN_LAST_NAME + " COLLATE NOCASE ASC"
  + "," + ContactsDB.COLUMN_FIRST_NAME + " COLLATE NOCASE ASC" ;

  // Creates a new loader after the initLoader () call
  @Override
  public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = { ContactsDB.ROW_ID, ContactsDB.COLUMN_LAST_NAME, ContactsDB.COLUMN_FIRST_NAME };
    CursorLoader cursorLoader = new CursorLoader(this,
    SomeContentProvider.CONTENT_URI, projection, null, null, orderBy);
    return cursorLoader;
  }

  @Override
  public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
    // Swap the new cursor in.
    // (The framework will take care of closing the old cursor once we return.)
    adapter.swapCursor(data); //Call requires Min API 11
  }

  @Override
  public void onLoaderReset(Loader<Cursor> loader) {
    // This is called when the last Cursor provided to onLoadFinished()
    // above is about to be closed.    
    // Data is no longer available, delete the reference
    adapter.swapCursor(null);
  }

} 

Answer 1

这是我用来在 ListView 上动态显示可绘制对象的代码，您必须在适配器上使用函数 setViewBinder：

mAdapter.setViewBinder(new ViewBinder() {
        public boolean setViewValue(View aView, Cursor aCursor, int aColumnIndex) {

            //Modification of the icon to display in the list
            if (aColumnIndex == aCursor.getColumnIndex(DatabaseHandler.RATE_EMOTION)) {
                int emotionID = aCursor.getInt(aColumnIndex);
                Drawable emotionDrawable = resources.getDrawable(R.drawable.ic_unknown_rate);

                //if emotion is set
                if(emotionID > 0){
                    String emotionDrawablePath = "ic_smi" + emotionID;          
                    int emotionDrawableID = resources.getIdentifier(emotionDrawablePath,"drawable", getPackageName());
                    //if a drawable is found
                    if(emotionDrawableID > 0){
                        emotionDrawable = resources.getDrawable(emotionDrawableID);
                    }
                }

                ImageView emotionImage = (ImageView) aView;                 
                emotionImage.setImageDrawable(emotionDrawable);
                return true;
            }

            return false;
        }
    });

您可以在此示例中看到，我根据从光标处获得的每一行的数据更改了可绘制对象。