Sqlite CursorAdapter-优快云博客

本文链接：https://blog.youkuaiyun.com/huaiyiheyuan/article/details/52088636

本文详细介绍如何在Android中创建数据库并使用CursorAdapter进行数据展示。包括定义数据库表结构、创建数据库工具类、实现增删改查操作及使用CursorAdapter绑定数据到ListView。

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一、用到CursorAdapter首先要用到数据库了
1、我们先来创建数据库，首先去官方找下资料
https://developer.android.com/training/basics/data-storage/databases.html
我就照着这个敲了下

/**
 * Created by Administrator on 2016/7/29.
 * 该代码段定义了单个表格的表格名称和列名称：
 */
public class FeedReaderContract {
    public FeedReaderContract() {
    }
    /* Inner class that defines the table contents */
    public static abstract class FeedEntry implements BaseColumns {
        public static final String TABLE_NAME = "entry";
        public static final String COULUMN_NAME_ENTRY_ID = "entryid";
        public static final String COLUMN_NAME_TITILE = "title";
        public static final String COLUMN_NAME_SUBTITLE = "subtitle";
    }
}

这样写方便不少，然后就是建个数据库工具类

/**
 * Created by Administrator on 2016/7/29.
 * 使用 SQL 辅助工具创建数据库
 */
public class FeedReaderDbHelper extends SQLiteOpenHelper {
    // If you change the database schema, you must increment the database version.
    public static final int DATABASE_VERSION = 1;
    public static final String DATABASE_NAME = "FeedReader.db";

    private static final String TEXT_TYPE = " TEXT";  //千万注意  引号后面的空格，这样系统才知道这个是表示数据类型的
    private static final String COMMA_SEP = ",";
    private static final String SQL_CREATE_ENTRIES = "CREATE TABLE " + FeedReaderContract.FeedEntry.TABLE_NAME + " (" +
            FeedReaderContract.FeedEntry._ID + " INTEGER PRIMARY KEY," +
            FeedReaderContract.FeedEntry.COULUMN_NAME_ENTRY_ID + TEXT_TYPE + COMMA_SEP +
            FeedReaderContract.FeedEntry.COLUMN_NAME_TITILE + TEXT_TYPE + ")";
    private static final String SQL_DELETE_ENTRIES = "DROP TABLE IF EXISTS " + FeedReaderContract.FeedEntry.TABLE_NAME;

    public FeedReaderDbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(SQL_CREATE_ENTRIES);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // This database is only a cache for online data, so its upgrade policy is
        // to simply to discard the data and start over
        db.execSQL(SQL_DELETE_ENTRIES);
        onCreate(db);
    }

    public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        onUpgrade(db, oldVersion, newVersion);
    }
}

代码里有个注意的地方，数据库就Ok了
接着就是对数据库的增删改查了，后面会给代码

2、开始用CursorAdapter

代码搬家

public class TodoCursorAdapter extends CursorAdapter {

    public TodoCursorAdapter(Context context, Cursor c) {
        super(context, c, 0);
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return LayoutInflater.from(context).inflate(R.layout.item_todo, parent, false);
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        // Find fields to populate in inflated template
        TextView tvBody = (TextView) view.findViewById(R.id.tvBody);
        TextView tvPriority = (TextView) view.findViewById(R.id.tvPriority);
        // Extract properties from cursor
        String title = cursor.getString(cursor.getColumnIndexOrThrow(FeedReaderContract.FeedEntry.COLUMN_NAME_TITILE));
        tvBody.setText(title);
    }
}

使用的地方

public class MainActivity extends AppCompatActivity {
    private boolean isShow;
    private RelativeLayout view;
    private SQLiteDatabase db;//修改工具类对象
    private TodoCursorAdapter todoAdaapter;


    /**
     * 将信息输入到数据库
     *
     * @param v
     */
    public void addDb(View v) {
        ContentValues values = null;
        for (int i = 1; i < 5; i++) {
            values = new ContentValues();
            values.put(FeedReaderContract.FeedEntry.COULUMN_NAME_ENTRY_ID, i);
            values.put(FeedReaderContract.FeedEntry.COLUMN_NAME_TITILE, "heh" + i);
            long newRowId = db.insert(FeedReaderContract.FeedEntry.TABLE_NAME, FeedReaderContract.FeedEntry.TABLE_NAME, values);
            todoAdaapter.changeCursor(queryDb());      //Cursor改变调用chanageCursor()方法
            if (newRowId != -1)
                Toast.makeText(MainActivity.this, "插入成功", Toast.LENGTH_SHORT).show();
        }
    }

    /**
     * 从数据库删除信息
     *
     * @param v
     */
    public void deleteDb(View v) {
        //Define 'where' part of query
        String selection = FeedReaderContract.FeedEntry.COULUMN_NAME_ENTRY_ID + " like ?";
        //Specify arguments in placeholder order.
//        String[] selectionArgs = {String.valueOf(FeedReaderContract.FeedEntry._ID)};
        String[] selectionArgs = {String.valueOf(2)};

        //Issue SQL statement.
        int i = db.delete(FeedReaderContract.FeedEntry.TABLE_NAME, selection, selectionArgs);

    }

    /**
     * 从数据库读取信息
     *
     * @param
     */
    public Cursor queryDb() {
        // Define a projection that specifies which columns from the database
        // you will actually use after this query.
        String[] projection = {FeedReaderContract.FeedEntry._ID,
                FeedReaderContract.FeedEntry.COULUMN_NAME_ENTRY_ID,
                FeedReaderContract.FeedEntry.COLUMN_NAME_TITILE};

        // How you want the results sorted in the resulting Cursor
        String sortOrder = FeedReaderContract.FeedEntry._ID + "DESC";

        Cursor c = db.query(FeedReaderContract.FeedEntry.TABLE_NAME, // The table to query
                projection,  //The columns to return
                null,  //  selection :  The columns for the WHERE clause
                null, //selectionArgs :  The values for the WHERE clause
                null,
                null,
                null/*  sortOrder  //The sort order*/
        );
//        while (c.moveToNext()) {
//            String titleName = c.getString(c.getColumnIndexOrThrow(FeedReaderContract.FeedEntry.COLUMN_NAME_TITILE));
//            Log.i("MainActivity", titleName);
//        }
        return c;
    }

    /**
     * 更新数据库
     *
     * @param v
     */
    public void updateDb(View v) {
        // New value for one column
        ContentValues values = new ContentValues();
        values.put(FeedReaderContract.FeedEntry.COLUMN_NAME_TITILE, "jahlajfajfjjfjf");
        // Which row to update, based on the ID
        String selection = FeedReaderContract.FeedEntry.COULUMN_NAME_ENTRY_ID + " LIKE ?";
        String[] selectionArgs = {String.valueOf(3)};
        int i = db.update(FeedReaderContract.FeedEntry.TABLE_NAME, values, selection, selectionArgs);
    }


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //初始化工具类实例
        FeedReaderDbHelper mDbHelper = new FeedReaderDbHelper(this);
        db = mDbHelper.getWritableDatabase();
//        initWindow();


        ListView lvCur = (ListView) findViewById(R.id.lv_cur);
        todoAdaapter = new TodoCursorAdapter(this, queryDb());
        lvCur.setAdapter(todoAdaapter);
    }