RecyclerView使用：深入 CursorAdapter（3）

问题

在使用listview的时候，如果数据源来自数据库，我们可能会使用到cursorAdapter

listiew.setAdapter(cursorAdapter) 是常见的用法

但是，当我们使用RecyclerView的时候，Adapter为cursorAdapter是会报错的。

到目前为止，RecyclerView是不支持cursorAdapter的，但在github上有网友通过改写，已经实现了支持

1. 借鉴

github：ExRecyclerViewLibrary

2. 使用

1. 添加下面加入类中的RecyclerViewCursorAdapter 和 CursorFilter到工程中 (第5步)

2. 新建自定义Adapter   (第3步)

3. RecyclerView.setAdapter  （第4步）

3. 新建自定义Adapter

继承RecyclerViewCursorAdapter

注意：下面代码进行了Listener的优化

public class ContactsAdapter extends RecyclerViewCursorAdapter<ContactsAdapter.MyViewHolder> {    private static final String TAG = "ContactsAdapter";    public ContactsAdapter(Context context, Cursor c, int flags) {        super(context, c, flags);    }    // new view     @Override    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        View view = LayoutInflater.from(parent.getContext())                .inflate(R.layout.list_item, parent, false);        MyViewHolder myViewHolder = new MyViewHolder(view);        ClickListener clickListener = new ClickListener();        myViewHolder.linearLayout.setOnClickListener(clickListener);        view.setTag(myViewHolder.linearLayout.getId(),clickListener);        return myViewHolder ;    }    // bind view     @Override    public void onBindViewHolder(final MyViewHolder holder, Cursor cursor) {        String name = cursor.getString(cursor.getColumnIndex(                ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));        String number =cursor.getString(cursor.getColumnIndex(                ContactsContract.CommonDataKinds.Phone.NUMBER));        long contactsId = Long.parseLong(cursor.getString(cursor.getColumnIndex(                ContactsContract.CommonDataKinds.Phone.RAW_CONTACT_ID)));        holder.contactName.setText(name);        ClickListener clickListener = (ClickListener) holder.itemView.getTag(                holder.linearLayout.getId());        clickListener.setContactsId(contactsId);    }    @Override    protected void onContentChanged() {    }    public static class MyViewHolder extends RecyclerView.ViewHolder{        private TextView contactName;        private LinearLayout linearLayout;        public MyViewHolder(View itemView) {            super(itemView);            contactName = (TextView) itemView.findViewById(R.id.contactNameText);            linearLayout  = (LinearLayout)itemView.findViewById(R.id.linearlayout);        }    }    private class ClickListener implements View.OnClickListener {        private long contactsId;        public void setContactsId(long contactsId) {            this.contactsId = contactsId;        }        @Override        public void onClick(View v) { Log.i(TAG,"contactsId:"+contactsId); }    }}

4. Activty中使用

mRecyclerView为RecyclerView实例

cusror为数据返回的cursor

 mRecyclerView.setAdapter(new ContactsAdapter(getActivity(), cursor,0));

5. 加入类

主要是引入2个类：RecyclerViewCursorAdapter 和 CursorFilter

RecyclerViewCursorAdapter：

/* * Copyright (C) 2013 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. *//* * Copyright (C) 2014 [e-mail] * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */import android.content.Context;import android.database.ContentObserver;import android.database.Cursor;import android.database.DataSetObserver;import android.os.Handler;import android.support.v7.widget.RecyclerView;import android.widget.Filter;import android.widget.FilterQueryProvider;import android.widget.Filterable;/** * Version 1.0 * * Date: 2014-07-07 19:53 * Author: [e-mail] * * Copyright © 2009-2014 LiGux.com. * */public abstract class RecyclerViewCursorAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH>  implements Filterable,        CursorFilter.CursorFilterClient {    /**     * Call when bind view with the cursor     * @param holder     * @param cursor     */    public abstract void onBindViewHolder(VH holder, Cursor cursor);    /**     * This field should be made private, so it is hidden from the SDK.     * {@hide}     */    protected boolean mDataValid;    /**     * The current cursor     */    protected Cursor mCursor;    /**     * This field should be made private, so it is hidden from the SDK.     * {@hide}     */    protected Context mContext;    /**     * The row id column     */    protected int mRowIDColumn;    /**     * This field should be made private, so it is hidden from the SDK.     * {@hide}     */    protected ChangeObserver mChangeObserver;    /**     * This field should be made private, so it is hidden from the SDK.     * {@hide}     */    protected DataSetObserver mDataSetObserver;    /**     * This field should be made private, so it is hidden from the SDK.     * {@hide}     */    protected CursorFilter mCursorFilter;    /**     * This field should be made private, so it is hidden from the SDK.     * {@hide}     */    protected FilterQueryProvider mFilterQueryProvider;    /**     * If set the adapter will register a content observer on the cursor and will call     * {@link #onContentChanged()} when a notification comes in.  Be careful when     * using this flag: you will need to unset the current Cursor from the adapter     * to avoid leaks due to its registered observers.  This flag is not needed     * when using a CursorAdapter with a     * {@link android.content.CursorLoader}.     */    public static final int FLAG_REGISTER_CONTENT_OBSERVER = 0x02;    /**     * Recommended constructor.     *     * @param c The cursor from which to get the data.     * @param context The context     * @param flags Flags used to determine the behavior of the adapter;     *              Currently it accept {@link #FLAG_REGISTER_CONTENT_OBSERVER}.     */    public RecyclerViewCursorAdapter(Context context, Cursor c, int flags) {        init(context, c, flags);    }    void init(Context context, Cursor c, int flags) {        boolean cursorPresent = c != null;        mCursor = c;        mDataValid = cursorPresent;        mContext = context;        mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1;        if ((flags & FLAG_REGISTER_CONTENT_OBSERVER) == FLAG_REGISTER_CONTENT_OBSERVER) {            mChangeObserver = new ChangeObserver();            mDataSetObserver = new MyDataSetObserver();        } else {            mChangeObserver = null;            mDataSetObserver = null;        }        if (cursorPresent) {            if (mChangeObserver != null) c.registerContentObserver(mChangeObserver);            if (mDataSetObserver != null) c.registerDataSetObserver(mDataSetObserver);        }        setHasStableIds(true);    }    /**     * Returns the cursor.     * @return the cursor.     */    @Override    public Cursor getCursor() {        return mCursor;    }    /**     * @see android.support.v7.widget.RecyclerView.Adapter#getItemCount()     */    @Override    public int getItemCount() {        if (mDataValid && mCursor != null) {            return mCursor.getCount();        } else {            return 0;        }    }    /**     * @see android.support.v7.widget.RecyclerView.Adapter#getItemId(int)     *     * @param position Adapter position to query     * @return     */    @Override    public long getItemId(int position) {        if (mDataValid && mCursor != null) {            if (mCursor.moveToPosition(position)) {                return mCursor.getLong(mRowIDColumn);            } else {                return 0;            }        } else {            return 0;        }    }    @Override    public void onBindViewHolder(VH holder, 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(holder, mCursor);    }    /**     * Change the underlying cursor to a new cursor. If there is an existing cursor it will be     * closed.     *     * @param cursor The new cursor to be used     */    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.     *     * @param newCursor The new cursor to be used.     * @return Returns the previously set Cursor, or null if there wasa not one.     * If the given new Cursor is the same instance is the previously set     * Cursor, null is also returned.     */    public Cursor swapCursor(Cursor newCursor) {        if (newCursor == mCursor) {            return null;        }        Cursor oldCursor = mCursor;        if (oldCursor != null) {            if (mChangeObserver != null) oldCursor.unregisterContentObserver(mChangeObserver);            if (mDataSetObserver != null) oldCursor.unregisterDataSetObserver(mDataSetObserver);        }        mCursor = newCursor;        if (newCursor != null) {            if (mChangeObserver != null) newCursor.registerContentObserver(mChangeObserver);            if (mDataSetObserver != null) newCursor.registerDataSetObserver(mDataSetObserver);            mRowIDColumn = newCursor.getColumnIndexOrThrow("_id");            mDataValid = true;            // notify the observers about the new cursor            notifyDataSetChanged();        } else {            mRowIDColumn = -1;            mDataValid = false;            // notify the observers about the lack of a data set            notifyDataSetChanged();//            notifyDataSetInvalidated();        }        return oldCursor;    }    /**     * <p>Converts the cursor into a CharSequence. Subclasses should override this     * method to convert their results. The default implementation returns an     * empty String for null values or the default String representation of     * the value.</p>     *     * @param cursor the cursor to convert to a CharSequence     * @return a CharSequence representing the value     */    public CharSequence convertToString(Cursor cursor) {        return cursor == null ? "" : cursor.toString();    }    /**     * Runs a query with the specified constraint. This query is requested     * by the filter attached to this adapter.     *     * The query is provided by a     * {@link android.widget.FilterQueryProvider}.     * If no provider is specified, the current cursor is not filtered and returned.     *     * After this method returns the resulting cursor is passed to {@link #changeCursor(Cursor)}     * and the previous cursor is closed.     *     * This method is always executed on a background thread, not on the     * application's main thread (or UI thread.)     *     * Contract: when constraint is null or empty, the original results,     * prior to any filtering, must be returned.     *     * @param constraint the constraint with which the query must be filtered     *     * @return a Cursor representing the results of the new query     *     * @see #getFilter()     * @see #getFilterQueryProvider()     * @see #setFilterQueryProvider(android.widget.FilterQueryProvider)     */    public Cursor runQueryOnBackgroundThread(CharSequence constraint) {        if (mFilterQueryProvider != null) {            return mFilterQueryProvider.runQuery(constraint);        }        return mCursor;    }    public Filter getFilter() {        if (mCursorFilter == null) {            mCursorFilter = new CursorFilter(this);        }        return mCursorFilter;    }    /**     * Returns the query filter provider used for filtering. When the     * provider is null, no filtering occurs.     *     * @return the current filter query provider or null if it does not exist     *     * @see #setFilterQueryProvider(android.widget.FilterQueryProvider)     * @see #runQueryOnBackgroundThread(CharSequence)     */    public FilterQueryProvider getFilterQueryProvider() {        return mFilterQueryProvider;    }    /**     * Sets the query filter provider used to filter the current Cursor.     * The provider's     * {@link android.widget.FilterQueryProvider#runQuery(CharSequence)}     * method is invoked when filtering is requested by a client of     * this adapter.     *     * @param filterQueryProvider the filter query provider or null to remove it     *     * @see #getFilterQueryProvider()     * @see #runQueryOnBackgroundThread(CharSequence)     */    public void setFilterQueryProvider(FilterQueryProvider filterQueryProvider) {        mFilterQueryProvider = filterQueryProvider;    }    /**     * Called when the {@link ContentObserver} on the cursor receives a change notification.     * The default implementation provides the auto-requery logic, but may be overridden by     * sub classes.     *     * @see ContentObserver#onChange(boolean)     */    protected abstract void onContentChanged();    private class ChangeObserver extends ContentObserver {        public ChangeObserver() {            super(new Handler());        }        @Override        public boolean deliverSelfNotifications() {            return true;        }        @Override        public void onChange(boolean selfChange) {            onContentChanged();        }    }    private class MyDataSetObserver extends DataSetObserver {        @Override        public void onChanged() {            mDataValid = true;            notifyDataSetChanged();        }        @Override        public void onInvalidated() {            mDataValid = false;            notifyDataSetChanged();//            notifyDataSetInvalidated();        }    }}

CursorFilter：

/* * Copyright (C) 2011 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */import android.widget.Filter;import android.database.Cursor;/** * The CursorFilter delegates most of the work to the * {@link android.widget.CursorAdapter}. Subclasses should override these * delegate methods to run the queries and convert the results into String * that can be used by auto-completion widgets. */class CursorFilter extends Filter {    CursorFilterClient mClient;    interface CursorFilterClient {        CharSequence convertToString(Cursor cursor);        Cursor runQueryOnBackgroundThread(CharSequence constraint);        Cursor getCursor();        void changeCursor(Cursor cursor);    }    CursorFilter(CursorFilterClient client) {        mClient = client;    }    @Override    public CharSequence convertResultToString(Object resultValue) {        return mClient.convertToString((Cursor) resultValue);    }    @Override    protected Filter.FilterResults performFiltering(CharSequence constraint) {        Cursor cursor = mClient.runQueryOnBackgroundThread(constraint);        FilterResults results = new FilterResults();        if (cursor != null) {            results.count = cursor.getCount();            results.values = cursor;        } else {            results.count = 0;            results.values = null;        }        return results;    }    @Override    protected void publishResults(CharSequence constraint, FilterResults results) {        Cursor oldCursor = mClient.getCursor();        if (results.values != null && results.values != oldCursor) {            mClient.changeCursor((Cursor) results.values);        }    }}