Android RecyclerView+；游标装载机+；内容提供者+&引用；“加载更多”；

我创建了一个活动，因为我正在为从数据库加载数据实现CursorLoader

我已经对该表的所有记录执行了该操作，但我希望加载30-30条记录，如加载更多功能

import android.content.ContentValues;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.widget.Toast;

import com.example.pagingproject.adapters.CustomCursorRecyclerViewAdapter;
import com.example.pagingproject.databases.RequestProvider;
import com.example.pagingproject.databases.TableItems;

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor> {

    public final int offset = 30;
    private int page = 0;

    private RecyclerView mRecyclerView;
    private boolean loadingMore = false;
    private Toast shortToast;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        LinearLayoutManager mLayoutManager = new LinearLayoutManager(this);
        CustomCursorRecyclerViewAdapter mAdapter = new CustomCursorRecyclerViewAdapter(this, null);

        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.setAdapter(mAdapter);

        int itemsCountLocal = getItemsCountLocal();
        if (itemsCountLocal == 0) {
            fillTestElements();
        }

        shortToast = Toast.makeText(this, "", Toast.LENGTH_SHORT);

        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);

                LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
                int lastVisibleItemPosition = layoutManager.findLastVisibleItemPosition();
                int maxPositions = layoutManager.getItemCount();

                if (lastVisibleItemPosition == maxPositions - 1) {
                    if (loadingMore)
                        return;

                    loadingMore = true;
                    page++;
                    getSupportLoaderManager().restartLoader(0, null, MainActivity.this);
                }
            }
        });

        getSupportLoaderManager().restartLoader(0, null, this);
    }

    private void fillTestElements() {
        int size = 1000;
        ContentValues[] cvArray = new ContentValues[size];
        for (int i = 0; i < cvArray.length; i++) {
            ContentValues cv = new ContentValues();
            cv.put(TableItems.TEXT, ("text " + i));
            cvArray[i] = cv;
        }

        getContentResolver().bulkInsert(RequestProvider.urlForItems(0), cvArray);
    }

    private int getItemsCountLocal() {
        int itemsCount = 0;

        Cursor query = getContentResolver().query(RequestProvider.urlForItems(0), null, null, null, null);
        if (query != null) {
            itemsCount = query.getCount();
            query.close();
        }
        return itemsCount;
    }

    /*loader*/

    @Override
    public Loader<Cursor> onCreateLoader(int id, Bundle args) {
        switch (id) {
            case 0:
                return new CursorLoader(this, RequestProvider.urlForItems(offset * page), null, null, null, null);
            default:
                throw new IllegalArgumentException("no id handled!");
        }
    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        switch (loader.getId()) {
            case 0:
                Log.d(TAG, "onLoadFinished: loading MORE");
                shortToast.setText("loading MORE " + page);
                shortToast.show();

                Cursor cursor = ((CustomCursorRecyclerViewAdapter) mRecyclerView.getAdapter()).getCursor();

                //fill all exisitng in adapter
                MatrixCursor mx = new MatrixCursor(TableItems.Columns);
                fillMx(cursor, mx);

                //fill with additional result
                fillMx(data, mx);

                ((CustomCursorRecyclerViewAdapter) mRecyclerView.getAdapter()).swapCursor(mx);


                handlerToWait.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        loadingMore = false;
                    }
                }, 2000);

                break;
            default:
                throw new IllegalArgumentException("no loader id handled!");
        }
    }

    private Handler handlerToWait = new Handler();

    private void fillMx(Cursor data, MatrixCursor mx) {
        if (data == null)
            return;

        data.moveToPosition(-1);
        while (data.moveToNext()) {
            mx.addRow(new Object[]{
                    data.getString(data.getColumnIndex(TableItems._ID)),
                    data.getString(data.getColumnIndex(TableItems.TEXT))
            });
        }
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        // TODO: 2016-10-13
    }

    //

    private static final String TAG = "MainActivity";

}

我试图创建查询并加载前30条记录，但我无法理解如何请求新记录

我的活动代码如下：

public class ProductListActivity extends AppCompatActivity
        implements LoaderManager.LoaderCallbacks<Cursor> {

    /**
     * Records in list
     */
    int offset = 0;

    /**
     * For Current Activity *
     */
    Context mContext;

    /**
     * Activity Binding
     */
    ActivityProductListBinding activityProductListBinding;

    /**
     * Product Adapter
     */
    ProductListAdapter productListAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        /**
         * DataBinding with XML
         */
        activityProductListBinding = DataBindingUtil.setContentView(this, R.layout.activity_product_list);

        /**
         * Getting Context
         */
        mContext = getApplicationContext();

        /***
         * TOOLBAR Settings...
         */
        setSupportActionBar(activityProductListBinding.toolbar);
        activityProductListBinding.toolbarTitleTextview.setText(R.string.string_title_products);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowTitleEnabled(false);

        final ActionBar ab = getSupportActionBar();
        if (ab != null)
            ab.setDisplayHomeAsUpEnabled(true);

        /**
         * RecyclerView Setup
         */
        GridLayoutManager manager = new GridLayoutManager(this, 2);
        activityProductListBinding.productListRecyclerView.setLayoutManager(manager);

        /**
         * First Time init Loader
         */
        getSupportLoaderManager().initLoader(1, null, this);
    }

    @Override
    public Loader<Cursor> onCreateLoader(int id, Bundle args) {
        final Uri CONTENT_URI = KOOPSContentProvider.CONTENT_URI_PRODUCT.buildUpon()
                .appendQueryParameter(KOOPSContentProvider.QUERY_PARAMETER_OFFSET,
                        String.valueOf(offset))
                .build();
        return new CursorLoader(this, CONTENT_URI ,null, null, null, null);
    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        //When the loader has loaded some data (either initially, or the
        //datasource has changed and a new cursor is being provided),
        //Then we'll swap out the cursor in our recyclerview's adapter
        // and we'll create the adapter if necessary
        Log.d(LogUtils.TAG, "Cursor : " + data.getCount());
        if (productListAdapter == null) {
            productListAdapter = new ProductListAdapter(this, data);
            activityProductListBinding.productListRecyclerView.setAdapter(productListAdapter);
        }
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        //If the loader is reset, we need to clear out the
        //current cursor from the adapter.
        productListAdapter.reQuery(null);
    }
}

我已尝试在适配器中合并光标，但出现错误：

FATAL EXCEPTION: main

Process: com.kevalam.koopsv3, PID: 25021

java.lang.IllegalStateException: Observer android.database.MergeCursor$1@570f82d is already registered.
    at android.database.Observable.registerObserver(Observable.java:49)
    at android.database.AbstractCursor.registerDataSetObserver(AbstractCursor.java:358)
    at android.database.CursorWrapper.registerDataSetObserver(CursorWrapper.java:222)
    at android.database.MergeCursor.<init>(MergeCursor.java:50)
    at com.kevalam.koops.adapter.ProductListAdapter.mergeCursor(ProductListAdapter.java:71)
    at com.kevalam.koops.ui.ProductListActivity.onLoadFinished(ProductListActivity.java:161)
    at com.kevalam.koops.ui.ProductListActivity.onLoadFinished(ProductListActivity.java:38)

致命异常：main
进程：com.kevalam.koopsv3，PID:25021
java.lang.IllegalStateException:Observer android.database.MergeCursor$1@570f82d已注册。
在android.database.Observable.registerObserver上（Observable.java:49）
位于android.database.AbstractCursor.registerDataSetObserver（AbstractCursor.java:358）
位于android.database.CursorWrapper.registerDataSetObserver（CursorWrapper.java:222）
位于android.database.MergeCursor.（MergeCursor.java:50）
位于com.kevalam.koops.adapter.ProductListAdapter.mergeCursor（ProductListAdapter.java:71）
位于com.kevalam.koops.ui.ProductListActivity.onLoadFinished（ProductListActivity.java:161）
位于com.kevalam.koops.ui.ProductListActivity.onLoadFinished（ProductListActivity.java:38）

已编辑（适配器代码）：

公共类ProductListAdapter扩展了RecyclerView.Adapter{
//因为当前形式的RecyclerView.Adapter本机不可用
//支持游标，我们包装了一个游标适配器来完成所有的工作
//对我们来说。
游标适配器mCursorAdapter；
活动mContext；
随机rnd；
公共产品列表适配器（AppCompatActivity上下文，游标c）{
mContext=上下文；
rnd=新随机数（）；
mCursorAdapter=新游标适配器（mContext，c，0）{
@凌驾
公共视图newView（上下文上下文、光标、视图组父对象）{
//把这里的景色放大
LayoutFlater充气器=（LayoutFlater）context.getSystemService（context.LAYOUT\u充气器\u服务）；
返回充气机。充气（R.layout.row\u product\u layout\u grid，parent，false）；
}
@凌驾
公共void bindView（视图、上下文上下文、光标）{
String productName=cursor.getString（cursor.getColumnIndex（产品名称））；
//绑定操作
（（TextView）view.findViewById（R.id.sub\u product\u name\u text\u view））.setText（productName）；
int color=color.argb（200，rnd.nextInt（256），rnd.nextInt（256），rnd.nextInt（256））；
字符串url=”http://dummyimage.com/300/“+color+”/ffffff&text=“+（cursor.getPosition（）+1）；
毕加索
.与（上下文）
.load（url）
.placeholder（R.mipmap.ic_launcher）//也可以是可绘制的
.into（（ImageView）view.findViewById（R.id.sub_产品_图像_视图））；
}
};
}
公共无效合并光标（光标c）{
if（mCursorAdapter！=null）{
Cursor[]cursorArray={mCursorAdapter.getCursor（），c}；
MergeCursor MergeCursor=新的MergeCursor（cursorArray）；
重新查询（合并光标）；
}
}
公共作废重新查询（光标c）{
if（mCursorAdapter！=null）{
mCursorAdapter.changeCursor（c）；
mCursorAdapter.notifyDataSetChanged（）；
notifyDataSetChanged（）；
}
}
@凌驾
public int getItemCount（）{
返回mCursorAdapter.getCount（）；
}
@凌驾
公共无效onBindViewHolder（ViewHolder，int位置）{
//将绑定操作传递给游标加载器
mCursorAdapter.getCursor（）.moveToPosition（position）；//已编辑：根据下面的注释中的建议添加了此行，谢谢：）
bindView（holder.view、mContext、mCursorAdapter.getCursor（））；
}
@凌驾
public ViewHolder onCreateViewHolder（视图组父级，int-viewType）{
//将充气机作业传递给光标适配器
视图v=mCursorAdapter.newView（mContext，mCursorAdapter.getCursor（），父级）；
返回新的视图持有者（v）；
}
公共静态类ViewHolder扩展了RecyclerView.ViewHolder{
视图；
公共视图持有者（视图项视图）{
超级（项目视图）；
视图=itemView.findViewById（R.id.product\u row\u card\u视图）；
}
}
}

---

任何人都可以帮忙，请提前感谢。

最近，我创建了一个TodoApp，其中包含了大多数必需的功能。

该应用程序包含以下相关功能：

1） 自定义

RecyclerView

，支持

光标

2） 内容提供程序对SQLite数据库执行基本CRUD操作

3） 轻松与内容提供商交互

4） 
CursorLoader
，它在基础数据库发生更改时立即更新
RecyclerView

剩下的就是实现更多的加载功能。Codepath有一篇非常好的文章。（如果需要任何帮助，请告诉我：）
更新01.10.2017
谷歌宣布了新的分页库，更多信息请点击此处


这是一个基于cursoradapter+recyclerview+provider的分页工作示例

我给你一步一步的代码+奖金与gif预览

但游标适配器上的IMHO分页毫无意义，因为db正在处理所有繁重的内容，并加载更多数据：）

第1步。创建数据库：

public class CustomSqliteOpenHelper extends SQLiteOpenHelper {

    private static final String TAG = "CustomSqliteOpenHelper";

    public CustomSqliteOpenHelper(Context context) {
        super(context, "db.db", null, 1);
    }

    @Override
    public void onOpen(SQLiteDatabase db) {
        super.onOpen(db);
    }

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

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL(TableItems.DROP_TABLE);
        onCreate(db);
    } 
}

第2步。创建表格

public class TableItems {
    public static final String NAME = TableItems.class.getSimpleName().toLowerCase();
    public static final String _ID = "_id";
    public static final String TEXT = "text";

    public static final String CREATE_TABLE =
            "CREATE TABLE " + NAME +
                    " ( " +
                    _ID + " integer primary key autoincrement, " +
                    TEXT + " text " +
                    " ); ";

    public static final String DROP_TABLE = "DROP TABLE IF EXISTS " + NAME;
    public static String[] Columns = new String[]{_ID, TEXT};
}

第3步。创建提供程序

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.support.annotation.NonNull;
import android.util.Log;

import com.example.pagingproject.BuildConfig;

public class RequestProvider extends ContentProvider {
    private static final String TAG = "RequestProvider";

    private SQLiteOpenHelper mSqliteOpenHelper;
    private static final UriMatcher sUriMatcher;

    public static final String AUTHORITY = BuildConfig.APPLICATION_ID + ".db";

    private static final int
            TABLE_ITEMS = 0;

    static {
        sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        sUriMatcher.addURI(AUTHORITY, TableItems.NAME + "/offset/" + "#", TABLE_ITEMS);
    }

    public static Uri urlForItems(int limit) {
        return Uri.parse("content://" + AUTHORITY + "/" + TableItems.NAME + "/offset/" + limit);
    }

    @Override
    public boolean onCreate() {
        mSqliteOpenHelper = new CustomSqliteOpenHelper(getContext());
        return true;
    }

    @Override
    synchronized public Cursor query(@NonNull Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {

        SQLiteDatabase db = mSqliteOpenHelper.getReadableDatabase();
        SQLiteQueryBuilder sqb = new SQLiteQueryBuilder();
        Cursor c = null;
        String offset;

        switch (sUriMatcher.match(uri)) {
            case TABLE_ITEMS: {
                sqb.setTables(TableItems.NAME);
                offset = uri.getLastPathSegment();
                break;
            }

            default:
                throw new IllegalArgumentException("uri not recognized!");
        }

        int intOffset = Integer.parseInt(offset);

        String limitArg = intOffset + ", " + 30;
        Log.d(TAG, "query: " + limitArg);
        c = sqb.query(db, projection, selection, selectionArgs, null, null, sortOrder, limitArg);

        c.setNotificationUri(getContext().getContentResolver(), uri);

        return c;
    }

    @Override
    public String getType(@NonNull Uri uri) {
        return BuildConfig.APPLICATION_ID + ".item";
    }

    @Override
    public Uri insert(@NonNull Uri uri, ContentValues values) {
        String table = "";
        switch (sUriMatcher.match(uri)) {
            case TABLE_ITEMS: {
                table = TableItems.NAME;
                break;
            }
        }

        long result = mSqliteOpenHelper.getWritableDatabase().insertWithOnConflict(table, null, values, SQLiteDatabase.CONFLICT_IGNORE);

        if (result == -1) {
            throw new SQLException("insert with conflict!");
        }

        Uri retUri = ContentUris.withAppendedId(uri, result);
        return retUri;
    }

    @Override
    public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
        return -1;
    }

    @Override
    public int update(@NonNull Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        return -1;
    }
}

import android.content.Context;
import android.database.Cursor;
import android.database.DataSetObserver;
import android.support.v7.widget.RecyclerView;
import android.view.ViewGroup;

/**
 * Created by skyfishjy on 10/31/14.
 */

public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {

    protected Context mContext;

    private Cursor mCursor;

    private boolean mDataValid;

    private int mRowIdColumn;

    private DataSetObserver mDataSetObserver;

    public CursorRecyclerViewAdapter(Context context, Cursor cursor) {
        mContext = context;
        mCursor = cursor;
        mDataValid = cursor != null;
        mRowIdColumn = mDataValid ? mCursor.getColumnIndex("_id") : -1;
        mDataSetObserver = new NotifyingDataSetObserver(this);
        if (mCursor != null) {
            mCursor.registerDataSetObserver(mDataSetObserver);
        }
    }

    public Cursor getCursor() {
        return mCursor;
    }

    @Override
    public int getItemCount() {
        if (mDataValid && mCursor != null) {
            return mCursor.getCount();
        }
        return 0;
    }

    @Override
    public long getItemId(int position) {
        if (mDataValid && mCursor != null && mCursor.moveToPosition(position)) {
            return mCursor.getLong(mRowIdColumn);
        }
        return 0;
    }

    @Override
    public void setHasStableIds(boolean hasStableIds) {
        super.setHasStableIds(true);
    }

    public static final String TAG = CursorRecyclerViewAdapter.class.getSimpleName();

    public abstract void onBindViewHolder(VH viewHolder, Cursor cursor);

    @Override
    public VH onCreateViewHolder(ViewGroup parent, int viewType) {
        return null;
    }

    @Override
    public void onBindViewHolder(VH viewHolder, int position) {
        if (!mDataValid) {
            throw new IllegalStateException("this should only be called when the cursor is valid");
        }
        if (!mCursor.moveToPosition(position)) {
            throw new IllegalStateException("couldn't move cursor to position " + position);
        }
        onBindViewHolder(viewHolder, mCursor);
    }

    /**
     * Change the underlying cursor to a new cursor. If there is an existing cursor it will be
     * closed.
     */
    public void changeCursor(Cursor cursor) {
        Cursor old = swapCursor(cursor);
        if (old != null) {
            old.close();
        }
    }

    /**
     * Swap in a new Cursor, returning the old Cursor.  Unlike
     * {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em>
     * closed.
     */
    public Cursor swapCursor(Cursor newCursor) {
        if (newCursor == mCursor) {
            return null;
        }
        final Cursor oldCursor = mCursor;
        if (oldCursor != null && mDataSetObserver != null) {
            oldCursor.unregisterDataSetObserver(mDataSetObserver);
        }
        mCursor = newCursor;
        if (mCursor != null) {
            if (mDataSetObserver != null) {
                mCursor.registerDataSetObserver(mDataSetObserver);
            }
            mRowIdColumn = newCursor.getColumnIndexOrThrow("_id");
            mDataValid = true;
            notifyDataSetChanged();
        } else {
            mRowIdColumn = -1;
            mDataValid = false;
            notifyDataSetChanged();
            //There is no notifyDataSetInvalidated() method in RecyclerView.Adapter
        }
        return oldCursor;
    }

    public void setDataValid(boolean mDataValid) {
        this.mDataValid = mDataValid;
    }

    private class NotifyingDataSetObserver extends DataSetObserver {
        private RecyclerView.Adapter adapter;

        public NotifyingDataSetObserver(RecyclerView.Adapter adapter) {
            this.adapter = adapter;
        }

        @Override
        public void onChanged() {
            super.onChanged();
            ((CursorRecyclerViewAdapter) adapter).setDataValid(true);
            adapter.notifyDataSetChanged();
        }

        @Override
        public void onInvalidated() {
            super.onInvalidated();
            ((CursorRecyclerViewAdapter) adapter).setDataValid(false);
        }
    }
}

import android.database.Cursor;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

public class CustomViewHolder extends RecyclerView.ViewHolder {

    public TextView textView1;

    public CustomViewHolder(View itemView) {
        super(itemView);
        textView1 = (TextView) itemView.findViewById(android.R.id.text1);
    }

    public void setData(Cursor c) {
        textView1.setText(c.getString(c.getColumnIndex("text")));
    }
}

第4步。创建一个抽象的游标适配器，我从StackOverflow自定义游标回收视图适配器中获取了示例

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.support.annotation.NonNull;
import android.util.Log;

import com.example.pagingproject.BuildConfig;

public class RequestProvider extends ContentProvider {
    private static final String TAG = "RequestProvider";

    private SQLiteOpenHelper mSqliteOpenHelper;
    private static final UriMatcher sUriMatcher;

    public static final String AUTHORITY = BuildConfig.APPLICATION_ID + ".db";

    private static final int
            TABLE_ITEMS = 0;

    static {
        sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        sUriMatcher.addURI(AUTHORITY, TableItems.NAME + "/offset/" + "#", TABLE_ITEMS);
    }

    public static Uri urlForItems(int limit) {
        return Uri.parse("content://" + AUTHORITY + "/" + TableItems.NAME + "/offset/" + limit);
    }

    @Override
    public boolean onCreate() {
        mSqliteOpenHelper = new CustomSqliteOpenHelper(getContext());
        return true;
    }

    @Override
    synchronized public Cursor query(@NonNull Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {

        SQLiteDatabase db = mSqliteOpenHelper.getReadableDatabase();
        SQLiteQueryBuilder sqb = new SQLiteQueryBuilder();
        Cursor c = null;
        String offset;

        switch (sUriMatcher.match(uri)) {
            case TABLE_ITEMS: {
                sqb.setTables(TableItems.NAME);
                offset = uri.getLastPathSegment();
                break;
            }

            default:
                throw new IllegalArgumentException("uri not recognized!");
        }

        int intOffset = Integer.parseInt(offset);

        String limitArg = intOffset + ", " + 30;
        Log.d(TAG, "query: " + limitArg);
        c = sqb.query(db, projection, selection, selectionArgs, null, null, sortOrder, limitArg);

        c.setNotificationUri(getContext().getContentResolver(), uri);

        return c;
    }

    @Override
    public String getType(@NonNull Uri uri) {
        return BuildConfig.APPLICATION_ID + ".item";
    }

    @Override
    public Uri insert(@NonNull Uri uri, ContentValues values) {
        String table = "";
        switch (sUriMatcher.match(uri)) {
            case TABLE_ITEMS: {
                table = TableItems.NAME;
                break;
            }
        }

        long result = mSqliteOpenHelper.getWritableDatabase().insertWithOnConflict(table, null, values, SQLiteDatabase.CONFLICT_IGNORE);

        if (result == -1) {
            throw new SQLException("insert with conflict!");
        }

        Uri retUri = ContentUris.withAppendedId(uri, result);
        return retUri;
    }

    @Override
    public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
        return -1;
    }

    @Override
    public int update(@NonNull Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        return -1;
    }
}

import android.content.Context;
import android.database.Cursor;
import android.database.DataSetObserver;
import android.support.v7.widget.RecyclerView;
import android.view.ViewGroup;

/**
 * Created by skyfishjy on 10/31/14.
 */

public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {

    protected Context mContext;

    private Cursor mCursor;

    private boolean mDataValid;

    private int mRowIdColumn;

    private DataSetObserver mDataSetObserver;

    public CursorRecyclerViewAdapter(Context context, Cursor cursor) {
        mContext = context;
        mCursor = cursor;
        mDataValid = cursor != null;
        mRowIdColumn = mDataValid ? mCursor.getColumnIndex("_id") : -1;
        mDataSetObserver = new NotifyingDataSetObserver(this);
        if (mCursor != null) {
            mCursor.registerDataSetObserver(mDataSetObserver);
        }
    }

    public Cursor getCursor() {
        return mCursor;
    }

    @Override
    public int getItemCount() {
        if (mDataValid && mCursor != null) {
            return mCursor.getCount();
        }
        return 0;
    }

    @Override
    public long getItemId(int position) {
        if (mDataValid && mCursor != null && mCursor.moveToPosition(position)) {
            return mCursor.getLong(mRowIdColumn);
        }
        return 0;
    }

    @Override
    public void setHasStableIds(boolean hasStableIds) {
        super.setHasStableIds(true);
    }

    public static final String TAG = CursorRecyclerViewAdapter.class.getSimpleName();

    public abstract void onBindViewHolder(VH viewHolder, Cursor cursor);

    @Override
    public VH onCreateViewHolder(ViewGroup parent, int viewType) {
        return null;
    }

    @Override
    public void onBindViewHolder(VH viewHolder, int position) {
        if (!mDataValid) {
            throw new IllegalStateException("this should only be called when the cursor is valid");
        }
        if (!mCursor.moveToPosition(position)) {
            throw new IllegalStateException("couldn't move cursor to position " + position);
        }
        onBindViewHolder(viewHolder, mCursor);
    }

    /**
     * Change the underlying cursor to a new cursor. If there is an existing cursor it will be
     * closed.
     */
    public void changeCursor(Cursor cursor) {
        Cursor old = swapCursor(cursor);
        if (old != null) {
            old.close();
        }
    }

    /**
     * Swap in a new Cursor, returning the old Cursor.  Unlike
     * {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em>
     * closed.
     */
    public Cursor swapCursor(Cursor newCursor) {
        if (newCursor == mCursor) {
            return null;
        }
        final Cursor oldCursor = mCursor;
        if (oldCursor != null && mDataSetObserver != null) {
            oldCursor.unregisterDataSetObserver(mDataSetObserver);
        }
        mCursor = newCursor;
        if (mCursor != null) {
            if (mDataSetObserver != null) {
                mCursor.registerDataSetObserver(mDataSetObserver);
            }
            mRowIdColumn = newCursor.getColumnIndexOrThrow("_id");
            mDataValid = true;
            notifyDataSetChanged();
        } else {
            mRowIdColumn = -1;
            mDataValid = false;
            notifyDataSetChanged();
            //There is no notifyDataSetInvalidated() method in RecyclerView.Adapter
        }
        return oldCursor;
    }

    public void setDataValid(boolean mDataValid) {
        this.mDataValid = mDataValid;
    }

    private class NotifyingDataSetObserver extends DataSetObserver {
        private RecyclerView.Adapter adapter;

        public NotifyingDataSetObserver(RecyclerView.Adapter adapter) {
            this.adapter = adapter;
        }

        @Override
        public void onChanged() {
            super.onChanged();
            ((CursorRecyclerViewAdapter) adapter).setDataValid(true);
            adapter.notifyDataSetChanged();
        }

        @Override
        public void onInvalidated() {
            super.onInvalidated();
            ((CursorRecyclerViewAdapter) adapter).setDataValid(false);
        }
    }
}

import android.database.Cursor;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

public class CustomViewHolder extends RecyclerView.ViewHolder {

    public TextView textView1;

    public CustomViewHolder(View itemView) {
        super(itemView);
        textView1 = (TextView) itemView.findViewById(android.R.id.text1);
    }

    public void setData(Cursor c) {
        textView1.setText(c.getString(c.getColumnIndex("text")));
    }
}

第6步。创建自定义视图夹

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.support.annotation.NonNull;
import android.util.Log;

import com.example.pagingproject.BuildConfig;

public class RequestProvider extends ContentProvider {
    private static final String TAG = "RequestProvider";

    private SQLiteOpenHelper mSqliteOpenHelper;
    private static final UriMatcher sUriMatcher;

    public static final String AUTHORITY = BuildConfig.APPLICATION_ID + ".db";

    private static final int
            TABLE_ITEMS = 0;

    static {
        sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        sUriMatcher.addURI(AUTHORITY, TableItems.NAME + "/offset/" + "#", TABLE_ITEMS);
    }

    public static Uri urlForItems(int limit) {
        return Uri.parse("content://" + AUTHORITY + "/" + TableItems.NAME + "/offset/" + limit);
    }

    @Override
    public boolean onCreate() {
        mSqliteOpenHelper = new CustomSqliteOpenHelper(getContext());
        return true;
    }

    @Override
    synchronized public Cursor query(@NonNull Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {

        SQLiteDatabase db = mSqliteOpenHelper.getReadableDatabase();
        SQLiteQueryBuilder sqb = new SQLiteQueryBuilder();
        Cursor c = null;
        String offset;

        switch (sUriMatcher.match(uri)) {
            case TABLE_ITEMS: {
                sqb.setTables(TableItems.NAME);
                offset = uri.getLastPathSegment();
                break;
            }

            default:
                throw new IllegalArgumentException("uri not recognized!");
        }

        int intOffset = Integer.parseInt(offset);

        String limitArg = intOffset + ", " + 30;
        Log.d(TAG, "query: " + limitArg);
        c = sqb.query(db, projection, selection, selectionArgs, null, null, sortOrder, limitArg);

        c.setNotificationUri(getContext().getContentResolver(), uri);

        return c;
    }

    @Override
    public String getType(@NonNull Uri uri) {
        return BuildConfig.APPLICATION_ID + ".item";
    }

    @Override
    public Uri insert(@NonNull Uri uri, ContentValues values) {
        String table = "";
        switch (sUriMatcher.match(uri)) {
            case TABLE_ITEMS: {
                table = TableItems.NAME;
                break;
            }
        }

        long result = mSqliteOpenHelper.getWritableDatabase().insertWithOnConflict(table, null, values, SQLiteDatabase.CONFLICT_IGNORE);

        if (result == -1) {
            throw new SQLException("insert with conflict!");
        }

        Uri retUri = ContentUris.withAppendedId(uri, result);
        return retUri;
    }

    @Override
    public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
        return -1;
    }

    @Override
    public int update(@NonNull Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        return -1;
    }
}

import android.content.Context;
import android.database.Cursor;
import android.database.DataSetObserver;
import android.support.v7.widget.RecyclerView;
import android.view.ViewGroup;

/**
 * Created by skyfishjy on 10/31/14.
 */

public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {

    protected Context mContext;

    private Cursor mCursor;

    private boolean mDataValid;

    private int mRowIdColumn;

    private DataSetObserver mDataSetObserver;

    public CursorRecyclerViewAdapter(Context context, Cursor cursor) {
        mContext = context;
        mCursor = cursor;
        mDataValid = cursor != null;
        mRowIdColumn = mDataValid ? mCursor.getColumnIndex("_id") : -1;
        mDataSetObserver = new NotifyingDataSetObserver(this);
        if (mCursor != null) {
            mCursor.registerDataSetObserver(mDataSetObserver);
        }
    }

    public Cursor getCursor() {
        return mCursor;
    }

    @Override
    public int getItemCount() {
        if (mDataValid && mCursor != null) {
            return mCursor.getCount();
        }
        return 0;
    }

    @Override
    public long getItemId(int position) {
        if (mDataValid && mCursor != null && mCursor.moveToPosition(position)) {
            return mCursor.getLong(mRowIdColumn);
        }
        return 0;
    }

    @Override
    public void setHasStableIds(boolean hasStableIds) {
        super.setHasStableIds(true);
    }

    public static final String TAG = CursorRecyclerViewAdapter.class.getSimpleName();

    public abstract void onBindViewHolder(VH viewHolder, Cursor cursor);

    @Override
    public VH onCreateViewHolder(ViewGroup parent, int viewType) {
        return null;
    }

    @Override
    public void onBindViewHolder(VH viewHolder, int position) {
        if (!mDataValid) {
            throw new IllegalStateException("this should only be called when the cursor is valid");
        }
        if (!mCursor.moveToPosition(position)) {
            throw new IllegalStateException("couldn't move cursor to position " + position);
        }
        onBindViewHolder(viewHolder, mCursor);
    }

    /**
     * Change the underlying cursor to a new cursor. If there is an existing cursor it will be
     * closed.
     */
    public void changeCursor(Cursor cursor) {
        Cursor old = swapCursor(cursor);
        if (old != null) {
            old.close();
        }
    }

    /**
     * Swap in a new Cursor, returning the old Cursor.  Unlike
     * {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em>
     * closed.
     */
    public Cursor swapCursor(Cursor newCursor) {
        if (newCursor == mCursor) {
            return null;
        }
        final Cursor oldCursor = mCursor;
        if (oldCursor != null && mDataSetObserver != null) {
            oldCursor.unregisterDataSetObserver(mDataSetObserver);
        }
        mCursor = newCursor;
        if (mCursor != null) {
            if (mDataSetObserver != null) {
                mCursor.registerDataSetObserver(mDataSetObserver);
            }
            mRowIdColumn = newCursor.getColumnIndexOrThrow("_id");
            mDataValid = true;
            notifyDataSetChanged();
        } else {
            mRowIdColumn = -1;
            mDataValid = false;
            notifyDataSetChanged();
            //There is no notifyDataSetInvalidated() method in RecyclerView.Adapter
        }
        return oldCursor;
    }

    public void setDataValid(boolean mDataValid) {
        this.mDataValid = mDataValid;
    }

    private class NotifyingDataSetObserver extends DataSetObserver {
        private RecyclerView.Adapter adapter;

        public NotifyingDataSetObserver(RecyclerView.Adapter adapter) {
            this.adapter = adapter;
        }

        @Override
        public void onChanged() {
            super.onChanged();
            ((CursorRecyclerViewAdapter) adapter).setDataValid(true);
            adapter.notifyDataSetChanged();
        }

        @Override
        public void onInvalidated() {
            super.onInvalidated();
            ((CursorRecyclerViewAdapter) adapter).setDataValid(false);
        }
    }
}

import android.database.Cursor;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

public class CustomViewHolder extends RecyclerView.ViewHolder {

    public TextView textView1;

    public CustomViewHolder(View itemView) {
        super(itemView);
        textView1 = (TextView) itemView.findViewById(android.R.id.text1);
    }

    public void setData(Cursor c) {
        textView1.setText(c.getString(c.getColumnIndex("text")));
    }
}

第7步。用sa编写代码