我已经在我的应用程序上取得了进展，但我仍然试图弄清楚需要实现什么来从sqlite表中检索我的自定义适配器中的按钮（在此示例中为imageview）状态，该表将保留所有行的条目（通过_id）已被加入书签。
下面，如果我的自定义SimpleCursorAdapter我已经能够使用setSelected（）更改imageview，那么现在我需要创建机制来识别已经加入书签的项目并将其存储在表格中。我已经对我所设想的内容进行了评论，但不确定如何实现它......
public class DxSimpleCursorAdapter extends SimpleCursorAdapter {
Context context;
Activity activity;
private DxDbAdapter mDbHelper;
public DxSimpleCursorAdapter(Context context, int layout, Cursor c,
String[] from, int[] to) {
super(context, layout, c, from, to);
this.context=context;
this.activity=(Activity) context;
}
@Override
public View getView(int position, View convertView, ViewGroup parent){
View row = super.getView(position, convertView, parent);
ImageView image = (ImageView) row.findViewById(R.id.fav);
//Query for _id of row item and see if there is an entry for it on the favourite table
//Then change ImageView to being selected image (yellow star)
//Else leave default image (greyed out)
image.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
ImageView fav = (ImageView) v.findViewById(R.id.fav);
fav.setImageResource(R.drawable.ic_fav);
long rowID = (Long) v.getTag();
Toast toast = Toast.makeText(context, "" + rowID, Toast.LENGTH_SHORT);
toast.show();
mDbHelper = new DxDbAdapter(context);
int result = mDbHelper.isFav(rowID);
if (result == 0) {
v.setSelected(true);
}
else {
v.setSelected(false);
}
}
});
return row;
}
}
另外，我有一个适用于我的数据库，我正在创建函数，以便能够在表中添加一个喜欢的条目，但我不知道如何在自定义游标适配器中调用数据库或如果我需要以不同的方式去做。
public class DxDbAdapter {
public static final String DIAG_ID = "_id";
public static final String DIAG_CAT = "category";
public static final String DIAG_SUB = "subcategory";
public static final String DIAG = "diagnosis";
public static final String DIAG_CODE = "diagcode";
public static final String FAV_CODE = "edid";
private static final String DATABASE_NAME = "dx";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
protected static Context mCtx;
private static class DatabaseHelper extends SQLiteOpenHelper {
public DatabaseHelper (Context context) {
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
String s;
try {
Toast.makeText(mCtx, "1", 2000).show();
InputStream in = mCtx.getResources().openRawResource(R.raw.sql);
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = builder.parse(in, null);
NodeList statements = doc.getElementsByTagName("statement");
for (int i=0; i<statements.getLength(); i++) {
s = statements.item(i).getChildNodes().item(0).getNodeValue();
db.execSQL(s);
}
} catch (Throwable t) {
Toast.makeText(mCtx, t.toString(), 50000).show();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS DiagLookups");
onCreate(db);
}
}
public DxDbAdapter(Context context) {
this.mCtx = context;
}
public DxDbAdapter open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDb.close();
}
public Cursor fetch(int level, String param) {
Cursor cursor = null;
switch (level) {
case 0:
cursor = mDb.rawQuery("Select distinct _id, diagnosis, diagcode, favourite From DiagLookup Where category = ? order by diagnosis asc", new String[]{""+param});
break;
case 1:
cursor = mDb.rawQuery("Select distinct _id, diagnosis, diagcode, favourite From DiagLookup Where subcategory = ? order by diagnosis asc", new String[]{""+param});
break;
}
return cursor;
}
public Cursor fetchFavs() {
Cursor cursor = mDb.rawQuery("Select distinct _id, diagnosis, diagcode, favourite From DiagLookup Where favourite = 1 order by diagnosis asc", null);
return cursor;
}
public int isFav(Long param) {
Cursor cursor = mDb.rawQuery("Select favourite From DiagLookup Where _id = ?", new String[]{""+param});
int result = cursor.getInt(cursor.getColumnIndex(FAV));
return result;
}
我的表格结构如下：
CREATE TABLE IF NOT EXISTS Lookup (
_id INTEGER PRIMARY KEY,
category VARCHAR(150),
subcategory VARCHAR(150),
diagnosis VARCHAR(150),
diagcode VARCHAR(150),
favourite INTEGER)
我有一个listactivity，我创建了db并打开（）它。从那里我将数据提取（）到光标并将其传递给我的DxSimpleCursorAdapter。
非常感谢任何指导。
由于
答案 0 :(得分：1)
您应该实施bindView()和newView()方法，以便您可以访问游标。在newView()中，您需要对布局进行充气：
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
LayoutInflater inflater = LayoutInflater.from(context); // you should put this in the constructor so you don't do it every time the newView() method is called
View row = inflater.inflate(R.layout.row_layout, null);
// even implement the view holder pattern for a small performance boost
ViewHolder holder = new ViewHolder();
holder.image = (ImageView) row.findViewById(R.id.the_id_of_the_image);
row.setTag(holder);
return row;
}
ViewHolder是适配器中的一个类，用于保存视图，因此每次我们要访问行视图时都不会搜索整个布局：
class ViewHolder {
ImageView image;
// other views that you have in your row layout
}
然后实现bindView()方法：
@Override
public void bindView(View v, Context con, Cursor cursor) {
ViewHolder holder = (ViewHolder) v.getTag() //retrieve the holder with the row views
// set the current image status
int status = cursor.getInt(cursor.getColumnIndex(FAV_CODE)); // get the status( I don't know how you store the favorite status, I assumed is an int in the FAV_CODE column, 1 for favorite, 0 for unpicked yet)
if (status == 1) {
// the user set as favorite
holder.image.setImageResource(R.drawable.favorite); // set the favorite drawable
} else {
// this isn't a favorite so put the default image
holder.image.setImageResource(R.drawable.normal); // set the normal drawable
}
//get the row id from the cursor that we will pass in the onClick method as a tag for the image
long id = cursor.getLong(cursor.getColumnIndex(DIAG_ID));
holder.image.setTag(new Long(id));
// set the image listener
holder.image.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
long rowID = (Long) v.getTag();
//there is no need to find the view, and you don't modify the imageview image from here
// query the database to find the row with the _id equal to rowID
// find out what value we have in the column with the image status (either 1 or 0 meaning favorite or not favorite)
// update the row with the new status (if you have 1 in the database then update the status with 0 , if you have 0 in the database then update the value with 1)
//call notifyDatasetChanged on the adapter to let the adapter know about the update, I don't know if this call will work with SimpleCursorAdapter, you may have to set a new adapter on the ListView with a new cursor.
}
});
}