简单使用SimpleCursorAdapter

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如果使用Sqlite，建议和ContentProvider结合使用。这样数据库的生命周期就不用自己管了。然后，如果要在比如ListView中显示，可以使用CursorAdapter。简化的办法是使用子类SimpleCursorAdapter。

以下就介绍一下使用sqlite+content provider+cursor adapter的最简单实现示例。太简单了，示例如图：

首先，要有个Content provider，如不了解如何实现，请参考编写最简单的Content Provider和在Content provider实现中使用SQLiteOpenHelper，下面写的是结合二者的：

public class RiverContentProvider extends ContentProvider {

    public static final Uri CONTENT_URI = Uri
            .parse("content://com.easymorse.cp.rivers");

    public static final String _ID = "_id";

    public static final String NAME = "name";

    public static final String LENGTH = "length";

    private static SQLiteDatabase database;

    private static final int DATABASE_VERSION = 2;

    private static final List<River> RIVERS = new ArrayList<River>();

    static {
        River river = new River("长江", 6380);
        RIVERS.add(river);

        river = new River("黄河", 5464);
        RIVERS.add(river);
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public String getType(Uri uri) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Uri insert(Uri uri, ContentValues contentValues) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public boolean onCreate() {
        database = new RiverDatabaseHelper(getContext(), "rivers", null,
                DATABASE_VERSION).getReadableDatabase();
        return database != null;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
        return database.query("rivers", projection, selection, selectionArgs,
                null, null, sortOrder);
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection,
            String[] selectionArgs) {
        // TODO Auto-generated method stub
        return 0;
    }

    private static class RiverDatabaseHelper extends SQLiteOpenHelper {

        public RiverDatabaseHelper(Context context, String name,
                CursorFactory factory, int version) {
            super(context, name, factory, version);
        }

        @Override
        public void onCreate(SQLiteDatabase database) {
            database.execSQL("create table if not exists rivers("
                    + " _id integer primary key autoincrement," + " name text,"
                    + "length integer" + ");");

            SQLiteStatement statement = database
                    .compileStatement("insert into rivers(name,length) values(?,?)");

            for (River r : RIVERS) {
                int index = 1;
                statement.bindString(index++, r.getName());
                statement.bindLong(index++, r.getLength());
                statement.executeInsert();
            }

            statement.close();
        }

        @Override
        public void onUpgrade(SQLiteDatabase database, int oldVersion,
                int newVersion) {
            database.execSQL("drop table if exists rivers");
            onCreate(database);
        }

    }

这里写的很简略，没用到的方法都没实现。

在总的布局中使用了ListView：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <ListView android:id="@+id/riverList" android:layout_width="fill_parent"
        android:layout_height="fill_parent" />
</LinearLayout>

使用了自定义的ListView布局，见：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="wrap_content">
    <TextView android:id="@+id/riverName" android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

最后是在Activity中使用contentprovider查询的cursor，生成ListView：

public class ListViewActivity extends Activity {

    private ListView riverListView;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        setRiverListViewAdapter();
    }

    private void setRiverListViewAdapter() {
        riverListView = (ListView) this.findViewById(R.id.riverList);

        Cursor cursor = managedQuery(RiverContentProvider.CONTENT_URI, null,
                null, null, null);
        CursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.row,
                cursor, new String[] { RiverContentProvider.NAME },
                new int[] { R.id.riverName });
        riverListView.setAdapter(adapter);
    }
}

源代码见：

http://easymorse.googlecode.com/svn/tags/CustomListViewDemo-0.1/

来源：oschina

链接：https://my.oschina.net/u/54100/blog/14846

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android

simplecursoradapter