test123/NotesListAdapter.java

/*
 * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
 *
 * 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.
 */


/*这段代码展示了一个自定义的 CursorAdapter 类 NotesListAdapter 的实现，主要用于显示一个包含笔记列表的适配器。这个适配器支持选择模式（choice mode），允许用户多选笔记条目进行批量操作。*/

package net.micode.notes.ui;

import android.content.Context;
import android.database.Cursor;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CursorAdapter;

import net.micode.notes.data.Notes;

import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;


public class NotesListAdapter extends CursorAdapter {
    private static final String TAG = "NotesListAdapter";
    private Context mContext;
    private HashMap<Integer, Boolean> mSelectedIndex;
    private int mNotesCount;
    private boolean mChoiceMode;

    public static class AppWidgetAttribute {
        public int widgetId;
        public int widgetType;
    };

    public NotesListAdapter(Context context) {
        super(context, null);
        mSelectedIndex = new HashMap<Integer, Boolean>();
        mContext = context;
        mNotesCount = 0;
    }          /*构造函数初始化了适配器的基本属性，包括上下文、存储选定索引的哈希表和笔记数量*/

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return new NotesLis tItem(context);
    }    /*此方法负责创建一个新的视图，这里返回的是一个 NotesListItem 视图对象*/

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        if (view instanceof NotesListItem) {
            NoteItemData itemData = new NoteItemData(context, cursor);
            ((NotesListItem) view).bind(context, itemData, mChoiceMode,
                    isSelectedItem(cursor.getPosition()));
        }
    }     /*此方法用于绑定数据到视图。这里将从 Cursor 中获取的数据绑定到 NotesListItem 对象上，并设置选择模式和当前项是否被选中*/

    public void setCheckedItem(final int position, final boolean checked) {
        mSelectedIndex.put(position, checked);
        notifyDataSetChanged();
    }

    public boolean isInChoiceMode() {
        return mChoiceMode;
    }     /*这两个方法分别用于设置选择模式和检查当前是否处于选择模式*/

    public void setChoiceMode(boolean mode) {
        mSelectedIndex.clear();
        mChoiceMode = mode;
    }

    public void selectAll(boolean checked) {
        Cursor cursor = getCursor();
        for (int i = 0; i < getCount(); i++) {
            if (cursor.moveToPosition(i)) {
                if (NoteItemData.getNoteType(cursor) == Notes.TYPE_NOTE) {
                    setCheckedItem(i, checked);
                }
            }
        }
    }     /*此方法遍历所有的笔记，并根据传入的布尔值设置所有笔记项为选中或取消选中*/

    public HashSet<Long> getSelectedItemIds() {
        HashSet<Long> itemSet = new HashSet<Long>();
        for (Integer position : mSelectedIndex.keySet()) {
            if (mSelectedIndex.get(position) == true) {
                Long id = getItemId(position);
                if (id == Notes.ID_ROOT_FOLDER) {
                    Log.d(TAG, "Wrong item id, should not happen");
                } else {
                    itemSet.add(id);
                }
            }
        }

        return itemSet;
    }       /*此方法返回一个包含所有被选中项ID的集合*/

    public HashSet<AppWidgetAttribute> getSelectedWidget() {
        HashSet<AppWidgetAttribute> itemSet = new HashSet<AppWidgetAttribute>();
        for (Integer position : mSelectedIndex.keySet()) {
            if (mSelectedIndex.get(position) == true) {
                Cursor c = (Cursor) getItem(position);
                if (c != null) {
                    AppWidgetAttribute widget = new AppWidgetAttribute();
                    NoteItemData item = new NoteItemData(mContext, c);
                    widget.widgetId = item.getWidgetId();
                    widget.widgetType = item.getWidgetType();
                    itemSet.add(widget);
                    /**
                     * Don't close cursor here, only the adapter could close it
                     */
                } else {
                    Log.e(TAG, "Invalid cursor");
                    return null;
                }
            }
        }
        return itemSet;
    }       /*此方法返回一个包含所有被选中小部件属性的集合*/

    public int getSelectedCount() {
        Collection<Boolean> values = mSelectedIndex.values();
        if (null == values) {
            return 0;
        }
        Iterator<Boolean> iter = values.iterator();
        int count = 0;
        while (iter.hasNext()) {
            if (true == iter.next()) {
                count++;
            }
        }
        return count;
    }     /*此方法计算并返回被选中项的数量*/

    public boolean isAllSelected() {
        int checkedCount = getSelectedCount();
        return (checkedCount != 0 && checkedCount == mNotesCount);
    }     /*此方法用于检查当前是否所有的笔记都被选中*/

    public boolean isSelectedItem(final int position) {
        if (null == mSelectedIndex.get(position)) {
            return false;
        }
        return mSelectedIndex.get(position);
    }     /*setCheckedItem 方法用于设置指定位置的项是否被选中，并通知适配器数据已改变。isSelectedItem 方法则用于检查指定位置的项是否已被选中*/

    @Override
    protected void onContentChanged() {
        super.onContentChanged();
        calcNotesCount();
    }

    @Override
    public void changeCursor(Cursor cursor) {
        super.changeCursor(cursor);
        calcNotesCount();
    }

    private void calcNotesCount() {
        mNotesCount = 0;
        for (int i = 0; i < getCount(); i++) {
            Cursor c = (Cursor) getItem(i);
            if (c != null) {
                if (NoteItemData.getNoteType(c) == Notes.TYPE_NOTE) {
                    mNotesCount++;
                }
            } else {
                Log.e(TAG, "Invalid cursor");
                return;
            }
        }
    }
}       /*此方法用于计算笔记的数量，只统计类型为 Notes.TYPE_NOTE 的条目*/