从 SQLite 数据库 Android 填充 Spinner

Populating Spinner From SQLite Database Android

提问by crv

I'm attempting to make a dynamic drop down that will be filled by a SQLite table. I have a Cursor object which I can pull the data I need from. I've been able to accomplish loading the values into the drop down with the code below:

我正在尝试制作一个将由 SQLite 表填充的动态下拉列表。我有一个 Cursor 对象，我可以从中提取我需要的数据。我已经能够使用以下代码将值加载到下拉列表中：

Spinner s = (Spinner) findViewById(R.id.spinner);
    ArrayAdapter adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    s.setAdapter(adapter);

    try{
        Cursor cursor = getAccounts();
        int accountnameIndex = cursor.getColumnIndexOrThrow(ACCOUNT_NAME);
        if(cursor.moveToFirst()){
            do{
                adapter.add(cursor.getString(accountnameIndex));
            } while(cursor.moveToNext());
        }
    } finally {
        MintLink.close();
    }

My problem is that I need the a selection from the drop down to also contain the RowID of the item selected. I need to be able to select one item and have access to the value of that item in the back end. For example, think of a drop down in HTML. Each drop down selection has it's own hidden value that is pulled. I need this value to be hidden for me to allow me to know which ID they choose.

我的问题是我需要从下拉列表中进行选择以包含所选项目的 RowID。我需要能够选择一个项目并在后端访问该项目的值。例如，想想 HTML 中的下拉菜单。每个下拉选择都有它自己的隐藏值被拉出。我需要为我隐藏这个值，让我知道他们选择了哪个 ID。

采纳答案by CommonsWare

Try using a SimpleCursorAdapterinstead of copying all the data by hand into an ArrayAdapter.

尝试使用 aSimpleCursorAdapter而不是手动将所有数据复制到ArrayAdapter.

回答by MindSpiker

This is an old question but the first one I found when figuring out this issue. Here is a detailed explanation with full source which may cut some legwork.

这是一个老问题，但我在解决这个问题时发现的第一个问题。这是带有完整源代码的详细说明，可能会减少一些麻烦。

The answer is indeed to use a SimpleCursorAdapter which handles a list of strings but also has special handling for a matched ID field that gets returned when a row is selected. The key to making this work is to know the two following obscure bits of information:

答案确实是使用 SimpleCursorAdapter 来处理字符串列表，但也对匹配的 ID 字段进行特殊处理，该字段在选择一行时返回。完成这项工作的关键是了解以下两个晦涩的信息：

1) When creating the cursor make sure the query returns a field titled "_id". This field need not be displayed anywhere but it's value will be passed back when a list item is selected.

1) 创建游标时，请确保查询返回标题为“_id”的字段。该字段不需要在任何地方显示，但它的值将在选择列表项时传回。

2) When creating a SimpleCursorAdapter you need to supply the TextView layout IDs where the row text will be placed. If using the android supplied layout android.R.layout.simple_spinner_item the text id you need to use is android.R.id.text1.

2) 创建 SimpleCursorAdapter 时，您需要提供放置行文本的 TextView 布局 ID。如果使用 android 提供的布局 android.R.layout.simple_spinner_item，则您需要使用的文本 ID 是 android.R.id.text1。

Main.xml

主文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <Spinner
        android:id="@+id/spinner1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        ></Spinner>
</RelativeLayout>

Activity code:

活动代码：

public class TesterActivity extends Activity {
public Context mContext;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    // just for this example:
    // create database table with an id field and a text field and add some data
    class MyDBHelper extends SQLiteOpenHelper {
        public MyDBHelper(Context context) {
            super(context, "someDB", null, 2);
        }
        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("CREATE TABLE someTable (someIDF INTEGER, someTextF TEXT)");
        }
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS someTable");
            onCreate(db);
            db.execSQL("INSERT INTO someTable (someIDF, someTextF) VALUES (54, 'Some text')");
            db.execSQL("INSERT INTO someTable (someIDF, someTextF) VALUES (99, 'Some more text')");
            db.execSQL("INSERT INTO someTable (someIDF, someTextF) VALUES (173, 'Even more text')");
        }
    }
    SQLiteDatabase db = new MyDBHelper(this).getWritableDatabase();

    // get a cursor from the database with an "_id" field
    Cursor c = db.rawQuery("SELECT someIDF AS _id, someTextF FROM someTable", null);

    // make an adapter from the cursor
    String[] from = new String[] {"someTextF"};
    int[] to = new int[] {android.R.id.text1};
    SimpleCursorAdapter sca = new SimpleCursorAdapter(this, android.R.layout.simple_spinner_item, c, from, to);

    // set layout for activated adapter
    sca.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 

    // get xml file spinner and set adapter 
    Spinner spin = (Spinner) this.findViewById(R.id.spinner1);
    spin.setAdapter(sca);

    // set spinner listener to display the selected item id
    mContext = this;
    spin.setOnItemSelectedListener(new OnItemSelectedListener() {
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id){
            Toast.makeText(mContext, "Selected ID=" + id, Toast.LENGTH_LONG).show();
        }
        public void onNothingSelected(AdapterView<?> parent) {}
        });
    }
}

回答by Benoit Duffez

Here's another answer with loaders and cursors.

这是加载器和游标的另一个答案。

In the activity/fragment creation (said fragment/activity must implement LoaderManager.LoaderCallbacks<Cursor>):

在活动/片段创建中（说片段/活动必须实现LoaderManager.LoaderCallbacks<Cursor>）：

final Spinner spinner = (Spinner) findViewById(R.id.spinner);
mAdapter = new MyCursorAdapter(getActivity());
spinner.setAdapter(mAdapter);
getLoaderManager().initLoader(SOME_INT_CONSTANT, null, this);

In your activity/fragment:

在您的活动/片段中：

@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    return new MyCursorLoader(getActivity(), args);
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
    mAdapter.swapCursor(data);
}

@Override
public void onLoaderReset(Loader<Cursor> loader) {
    mAdapter.swapCursor(null);
}

Here's the cursor adapter:

这是光标适配器：

class MyCursorAdapter extends CursorAdapter {
    class ViewsHolder {
        TextView text1, text2;
    }

    public MyCursorAdapter(Context context, Bundle args) {
        super(context, null, false);
        // do something with args
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        View v = LayoutInflater.from(context).inflate(R.layout.your_item_layout, parent, false);
        ViewsHolder holder = new ViewsHolder();
        holder.text1 = (TextView) v.findViewById(R.id.text1);
        holder.text2 = (TextView) v.findViewById(R.id.text2);
        v.setTag(holder);
        return v;
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        ViewsHolder holder = (ViewsHolder) view.getTag();
        String text1 = cursor.getString(cursor.getColumnIndex(KEY_TEXT1));
        String text2 = cursor.getString(cursor.getColumnIndex(KEY_TEXT2));
        holder.text1.setText(text1);
        holder.text2.setText(text2);
    }
}

Here's the cursor loader:

这是游标加载器：

public class MyCursorLoader extends CursorLoader {
    private final YourSQLiteDbAdapter mHelper;

    public MyCursorLoader(Context context) {
        super(context);
        mHelper = new YourSQLiteDbAdapter(context);
        mHelper.openReadOnly();
    }

    @Override
    public Cursor loadInBackground() {
        return mHelper.selectYourDataAsACursor();
    }

    @Override
    protected void onStopLoading() {
        super.onStopLoading();
        mHelper.close();
    }
}

Using this you get:

使用它你会得到：

• no use of deprecated APIs
• use of the loader API
• customized adapter / layouts
• view recycling
• API level 4 backward compatible (through support lib)
• background thread data loading

• 不使用已弃用的 API
• 加载器 API 的使用
• 定制的适配器/布局
• 查看回收
• API 级别 4 向后兼容（通过支持库）
• 后台线程数据加载

回答by Anji

Example of data binding can be found here.

可以在此处找到数据绑定示例。

http://developer.android.com/guide/topics/ui/binding.html

http://developer.android.com/guide/topics/ui/binding.html

check "Filling the Layout with Data" section for usage of SimpleCursorAdapter

检查“使用数据填充布局”部分以了解使用情况 SimpleCursorAdapter