Android将对象保存为sqlite中的blob [英] Android Save object as blob in sqlite
问题描述
gridview
。我想在sqlite中将它的项目保存为blob。所以当我打开保存sqlite病态数据的列表只需加载保存项目
并调用 adapter.notifyDataSetChanged
到我的 gridview
我试过这个,但是得到 NotSerializableException
错误
列表项目= new ArrayList();
public static byte [] serializeObject(Object o){
ByteArrayOutputStream bos = new ByteArrayOutputStream();
尝试{
ObjectOutput out = new ObjectOutputStream(bos);
out.writeObject(o);
out.close();
//获取序列化对象的字节
byte [] buf = bos.toByteArray();
return buf;
} catch(IOException ioe){
Log.e(serializeObject,error,ioe);
返回null;
}
}
我的插入行
public long insertRow(byte [] data){
/ *
* CHANGE 3:
* /
// TODO:用新字段更新行中的数据。
// TODO:同时改变函数的参数为你所需要的!
//创建行的数据:
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_DATA,data);
//将其插入数据库。
返回db.insert(DATABASE_TABLE,null,initialValues);
}
然后插入序列化对象
myDB.insertRow(MyDBAdapter.serializeObject(items));
我也很迷惑。我应该保存适配器还是保存项目列表?
我将数据存储为BLOB的方式是通过将它们转换为JSON然后存储字节。
例如
ArrayList< Person> persons = new ArrayList<>();
Gson gson = new Gson();
ContentValues values = new ContentValues();
values.put(MyProvider.KEY_DATA,gson.toJson(persons).getBytes());
//插入或更新DB
然后返回列表
byte [] blob = cursor.getBlob(cursor.getColumnIndex(MyProvider.KEY_DATA));
String json = new String(blob);
Gson gson = new Gson();
ArrayList< Person> people = gson.fromJson(json,new TypeToken< ArrayList< Person>>()
{} .getType());
编辑:要回答最后一个问题,您应该存储您的数据(项目列表) p>
is this right. I have this gridview
. I want to save its item as blob in sqlite. so when i open the list of save data in sqlite ill just load the save items
and call adapter.notifyDataSetChanged
to my gridview
I tried this one but I get NotSerializableException
error
List items = new ArrayList();
public static byte[] serializeObject(Object o) {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try {
ObjectOutput out = new ObjectOutputStream(bos);
out.writeObject(o);
out.close();
// Get the bytes of the serialized object
byte[] buf = bos.toByteArray();
return buf;
} catch (IOException ioe) {
Log.e("serializeObject", "error", ioe);
return null;
}
}
my insert row
public long insertRow(byte[] data) {
/*
* CHANGE 3:
*/
// TODO: Update data in the row with new fields.
// TODO: Also change the function's arguments to be what you need!
// Create row's data:
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_DATA, data);
// Insert it into the database.
return db.insert(DATABASE_TABLE, null, initialValues);
}
then I insert the serialize object
myDB.insertRow(MyDBAdapter.serializeObject(items));
also i'm confuse. should i save the adapter or the list of items'?
The way I store data as BLOB in my DB, is by converting them to JSON and then storing the bytes. e.g.
ArrayList<Person> persons = new ArrayList<>();
Gson gson = new Gson();
ContentValues values = new ContentValues();
values.put(MyProvider.KEY_DATA, gson.toJson(persons).getBytes());
// insert or update the DB
And to get the list back
byte[] blob = cursor.getBlob(cursor.getColumnIndex(MyProvider.KEY_DATA));
String json = new String(blob);
Gson gson = new Gson();
ArrayList<Person> persons = gson.fromJson(json, new TypeToken<ArrayList<Person>>()
{}.getType());
Edit: to answer your last question, you should store your data (list of items).
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