在阅读本文之前,如果您不知道如何创建数据库,请点击此链接.
好的,让我们开始在数据库中存储一些收藏夹..
你还应该从json,post的id解析并将它存储在数据库的第一个表中,这样你就可以比较后面的id和第二个表中用于存储收藏夹的行的id.
创建表格
这些是我的表
// CREATE TABLES
private static final String CREATE_FUN_FACTS_TABLE = "CREATE TABLE " + TABLE_NAME + "("
+ KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ POST_ID + " INTEGER,"
+ KEY_DESC + " TEXT,"
+ KEY_IMAGE + " TEXT,"
+ KEY_SOURCE + " TEXT" + ")";
private static final String CREATE_FAVS_TABLE = "CREATE TABLE " + TABLE_FAVS + "("
+ FAVS_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ FACTS_ID + " INTEGER" + ")";
现在我们将一些项目添加到第一个表中
// ADDING NEW FACTS ITEM
public void addItem(FunFactsData item) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(POST_ID, item.getId());
values.put(KEY_DESC, item.getDescription());
values.put(KEY_IMAGE, item.getImagePath());
values.put(KEY_SOURCE, item.getSource());
// INSERTING ROW
db.insert(TABLE_NAME, null, values);
db.close(); // CLOSING DATABASE CONNECTION
}
现在让我们在第二个表中添加一些最喜欢的东西
// ADDING NEW FAVORITE
public void addToFavorite(FunFactsData savedItem) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(FACTS_ID, savedItem.getId());
// INSERTING ROW
db.insert(TABLE_FAVS, null, values);
db.close();
}
从最喜欢的物品中取出物品的方法
// REMOVING FROM FAVORITE
public void removeFromFavorite(FunFactsData removedItem) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_FAVS, FACTS_ID + " = ? ",
new String[]{String.valueOf(removedItem.getId())});
db.close();
}
这是获得所有收藏的方法
// GETTING ALL FAVORITES public ListgetFavorites() { List funFactsDataList = new ArrayList<>(); // BUILD THE QUERY String query = "SELECT * FROM " + TABLE_NAME; String query2 = " INNER JOIN " + TABLE_FAVS; String query3 = " ON " + POST_ID + " = " + FACTS_ID + " GROUP BY " + FACTS_ID; // GET REFERENCE TO WRITABLE DB SQLiteDatabase db = this.getWritableDatabase(); Cursor cursor = db.rawQuery(query + query2 + query3, null); // GO OVER EACH ROW, AND GET FAVORITES FROM FAVORITES TABLE FunFactsData fact; if (cursor.moveToFirst()) { do { fact = new FunFactsData(); fact.setId(cursor.getInt(1)); fact.setDescription(cursor.getString(2)); fact.setImagePath(cursor.getString(3)); fact.setSource(cursor.getString(4)); funFactsDataList.add(fact); } while (cursor.moveToNext()); } return funFactsDataList; }
从DB获取所有项目的方法
// GET ALL DATA FROM DATABASE public ListgetAllFunFacts() { List funFactsDataList = new ArrayList<>(); // 1. BUILD THE QUERY String query = "SELECT * FROM " + TABLE_NAME; // 2. GET REFERENCE TO WRITABLE DB SQLiteDatabase db = this.getWritableDatabase(); Cursor cursor = db.rawQuery(query, null); // 3. GO OVER EACH ROW, BUILD FUN FACTS AND ADD IT TO LIST FunFactsData fact; if (cursor.moveToFirst()) { do { fact = new FunFactsData(); fact.setId(cursor.getInt(1)); fact.setDescription(cursor.getString(2)); fact.setImagePath(cursor.getString(3)); fact.setSource(cursor.getString(4)); // Add fun fac to facts funFactsDataList.add(fact); } while (cursor.moveToNext()); } Log.d("getAllFunFacts()", funFactsDataList.toString()); // RETURN FACT return funFactsDataList; }
这就是我们将如何存储从JSON到DATABASE的项目
@Override
public void getData(String link) {
try {
JSONObject response = new JSONObject(link);
JSONArray posts = response.getJSONArray("posts");
facts = new ArrayList<>();
shuffleJsonArray(posts);
for (int i = 0; i < posts.length(); i++) {
JSONObject obj = posts.getJSONObject(i);
JSONObject customFields = obj.getJSONObject("custom_fields");
FunFactsData funFactsData = new FunFactsData();
funFactsData.setId(obj.getInt("id"));
funFactsData.setImagePath(obj.getString("thumbnail"));
funFactsData.setDescription(customFields.optString("description"));
funFactsData.setSource(customFields.optString("source"));
facts.add(funFactsData);
dataBase.deleteRecords(); // "DELETE FROM " + TABLE_NAME, so everytime we get data from json, we will delete records from database and store new, but as far as we got id of post, we are good!
for (FunFactsData data : facts) { // go through loop for getting all objects and add them to database
dataBase.addItem(data); // add items do database
}
facts = (ArrayList) dataBase.getAllFunFacts(); // retrieve items from database
adapter = new FunFactsListAdapter(HomeActivity.this, facts);
flyingContainer.setAdapter(adapter); // setting addapter
loadMoreData.setVisibility(View.INVISIBLE);
noMoreData.setVisibility(View.INVISIBLE);
}
hidePDialog();
adapter.notifyDataSetChanged();
} catch (Exception e) {
e.printStackTrace();
}
}
现在我们得到了我们正在收藏的部分
我已经在我的适配器中编写了逻辑,所有魔法都在那里发生..
// Here we are checking if item with specified post id we are getting from json exists in second database.
private boolean checkFavoriteItem(FunFactsData checkItem) {
boolean check = false;
List facts = dataBase.getFavorites();
if (facts != null) {
for (FunFactsData data : facts) {
int id = data.getId();
int id2 = checkItem.getId();
if (id == id2) {
check = true;
break;
}
}
}
return check;
}
// Here i'm storing item to favorite
holder.favoriteIcon.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String getTag = holder.favoriteIcon.getTag().toString();
if (getTag.equalsIgnoreCase("gray")) {
dataBase.addToFavorite(data);
toast(context.getString(R.string.add_favorite));
holder.favoriteIcon.setTag("red");
holder.favoriteIcon.setImageResource(R.drawable.heart_red);
} else {
dataBase.removeFromFavorite(data);
toast(context.getString(R.string.remove_favorite));
holder.favoriteIcon.setTag("gray");
holder.favoriteIcon.setImageResource(R.drawable.heart);
}
mSmallBang.bang(v);
}
});
// i think this is clear also what i'm doing here.
if (checkFavoriteItem(data)) {
holder.favoriteIcon.setImageResource(R.drawable.heart_red);
holder.favoriteIcon.setTag("red");
} else {
holder.favoriteIcon.setImageResource(R.drawable.heart);
holder.favoriteIcon.setTag("gray");
}
我希望您能够根据我的代码管理您的代码并解决您的问题!
UPDATE
mRecyclerView.addOnItemTouchListener(new GiftsFavoriteList.RecyclerTouchListener(TagGiftsActivity.this, mRecyclerView, new GiftsFavoriteList.ClickListener() {
@Override
public void onClick(View view, int position) {
Intent intent = new Intent(TagGiftsActivity.this, GiftSingleActivity.class);
GiftItem selectedItem = mAdapter.getItem(position); // you can create method in adapter for getting specific item in row or use this -- arrayList.get(position); That is the same. I just used this in adapter.
intent.putExtra("selected_item", selectedItem);
startActivity(intent);
}
然后你需要使你的类实现Serializable,如下所示:
public class YourClass implements Serializable
接下来,我们需要从此活动获得对我们接收您的类对象的活动的意图.
// GETTING INTENT FROM PREVIOUS ACTIVITY
final Intent i = getIntent();
// GETTING POSITION OF SELECTED ITEM
GiftItem selectedItem = (GiftItem) i.getSerializableExtra("selected_item");
我在适配器中用于检查喜欢的项目的相同逻辑是在单个视图项目中.在这里,我们还检查项目是否在收藏夹中,因此我们可以设置适当的图像资源.
if (checkFavoriteItem(selectedItem)) {
favorite.setImageResource(R.drawable.ic_favorite);
favorite.setTag("red");
} else {
favorite.setImageResource(R.drawable.ic_add_favorite);
favorite.setTag("gray");
}
在这里我们将项目添加到收藏夹:
String tag = favorite.getTag().toString();
if (tag.equalsIgnoreCase("gray")) {
dbh.addToFavorite(selectedItem);
toast("Added to favorites!");
favorite.setImageResource(R.drawable.ic_favorite);
favorite.setTag("red");
} else {
dbh.removeFromFavorite(selectedItem);
toast("Removed from favorites!");
favorite.setImageResource(R.drawable.ic_add_favorite);
favorite.setTag("gray");
}
}
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