diff --git a/NotesProvider.java b/NotesProvider.java
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+/*
+ * 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.
+ */
+
+package net.micode.notes.data;
+
+// 导入Android框架中用于ContentProvider的相关类
+import android.app.SearchManager;
+import android.content.ContentProvider;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.content.Intent;
+import android.content.UriMatcher;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.net.Uri;
+import android.text.TextUtils;
+import android.util.Log;
+
+// 导入应用内部定义的类和接口
+import net.micode.notes.R;
+import net.micode.notes.data.Notes.DataColumns;
+import net.micode.notes.data.Notes.NoteColumns;
+import net.micode.notes.data.NotesDatabaseHelper.TABLE;
+
+// 继承ContentProvider类，创建NotesProvider类，用于管理笔记数据
+public class NotesProvider extends ContentProvider {
+    // Uri匹配器，用于识别不同的URI路径
+    private static final UriMatcher mMatcher;
+
+    // 数据库帮助类实例，用于操作数据库
+    private NotesDatabaseHelper mHelper;
+
+    // 日志标签，用于Log日志输出
+    private static final String TAG = "NotesProvider";
+
+    // 定义不同的URI代码，用于匹配不同的URI路径
+    private static final int URI_NOTE            = 1;
+    private static final int URI_NOTE_ITEM       = 2;
+    private static final int URI_DATA            = 3;
+    private static final int URI_DATA_ITEM       = 4;
+    private static final int URI_SEARCH          = 5;
+    private static final int URI_SEARCH_SUGGEST  = 6;
+
+    // 静态初始化块，初始化Uri匹配器
+    static {
+        mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
+        mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
+        mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
+        mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
+        mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);
+        mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
+    }
+
+    // 定义搜索结果的投影，包括ID、摘要等信息
+    /**
+     * x'0A'代表sqlite中的'\n'字符。为了在搜索结果中显示更多信息，
+     * 我们将截取标题和内容中的'\n'和空白。
+     */
+    private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
+        + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
+        + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + ","
+        + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_2 + ","
+        + R.drawable.search_result + " AS " + SearchManager.SUGGEST_COLUMN_ICON_1 + ","
+        + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
+        + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
+
+    // 定义笔记摘要搜索查询
+    private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
+        + " FROM " + TABLE.NOTE
+        + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
+        + " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER
+        + " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;
+
+    // onCreate方法，初始化数据库帮助类实例
+    @Override
+    public boolean onCreate() {
+        mHelper = NotesDatabaseHelper.getInstance(getContext());
+        return true;
+    }
+
+    // query方法，处理查询请求
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
+            String sortOrder) {
+        Cursor c = null;
+        SQLiteDatabase db = mHelper.getReadableDatabase();
+        String id = null;
+        // 根据URI匹配结果，执行不同的查询操作
+        switch (mMatcher.match(uri)) {
+            case URI_NOTE:
+                // 查询笔记表
+                c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
+                        sortOrder);
+                break;
+            case URI_NOTE_ITEM:
+                // 查询单个笔记项
+                id = uri.getPathSegments().get(1);
+                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_DATA:
+                // 查询数据表
+                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
+                        sortOrder);
+                break;
+            case URI_DATA_ITEM:
+                // 查询单个数据项
+                id = uri.getPathSegments().get(1);
+                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_SEARCH:
+            case URI_SEARCH_SUGGEST:
+                // 处理搜索请求
+                if (sortOrder != null || projection != null) {
+                    throw new IllegalArgumentException(
+                            "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
+                }
+
+                String searchString = null;
+                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
+                    if (uri.getPathSegments().size() > 1) {
+                        searchString = uri.getPathSegments().get(1);
+                    }
+                } else {
+                    searchString = uri.getQueryParameter("pattern");
+                }
+
+                if (TextUtils.isEmpty(searchString)) {
+                    return null;
+                }
+
+                try {
+                    searchString = String.format("%%%s%%", searchString);
+                    c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
+                            new String[] { searchString });
+                } catch (IllegalStateException ex) {
+                    Log.e(TAG, "got exception: " + ex.toString());
+                }
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        // 设置通知URI，以便在数据变化时通知外界
+        if (c != null) {
+            c.setNotificationUri(getContext().getContentResolver(), uri);
+        }
+        return c;
+    }
+}
+
+   
+以下是对代码中关键部分的注释：
+
+java
+/**
+ * 实现ContentProvider接口的insert方法，用于插入新的数据。
+ * @param uri 请求的URI，用于确定插入数据的表。
+ * @param values 包含要插入数据的ContentValues。
+ * @return 插入数据的URI，包括ID。
+ */
+@Override
+public Uri insert(Uri uri, ContentValues values) {
+    // 获取可写数据库实例
+    SQLiteDatabase db = mHelper.getWritableDatabase();
+    long dataId = 0, noteId = 0, insertedId = 0;
+    // 使用UriMatcher匹配URI，确定插入哪个表
+    switch (mMatcher.match(uri)) {
+        case URI_NOTE:
+            // 插入笔记数据
+            insertedId = noteId = db.insert(TABLE.NOTE, null, values);
+            break;
+        case URI_DATA:
+            // 插入数据，如果包含笔记ID，则记录
+            if (values.containsKey(DataColumns.NOTE_ID)) {
+                noteId = values.getAsLong(DataColumns.NOTE_ID);
+            } else {
+                Log.d(TAG, "Wrong data format without note id:" + values.toString());
+            }
+            insertedId = dataId = db.insert(TABLE.DATA, null, values);
+            break;
+        default:
+            // 如果URI不匹配，则抛出异常
+            throw new IllegalArgumentException("Unknown URI " + uri);
+    }
+    // 如果插入笔记ID大于0，通知变化
+    if (noteId > 0) {
+        getContext().getContentResolver().notifyChange(
+                ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
+    }
+    // 如果插入数据ID大于0，通知变化
+    if (dataId > 0) {
+        getContext().getContentResolver().notifyChange(
+                ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
+    }
+    // 返回插入数据的URI
+    return ContentUris.withAppendedId(uri, insertedId);
+}
+
+/**
+ * 实现ContentProvider接口的delete方法，用于删除数据。
+ * @param uri 请求的URI，用于确定删除数据的表。
+ * @param selection 删除条件。
+ * @param selectionArgs 删除条件的参数。
+ * @return 删除的行数。
+ */
+@Override
+public int delete(Uri uri, String selection, String[] selectionArgs) {
+    int count = 0;
+    String id = null;
+    SQLiteDatabase db = mHelper.getWritableDatabase();
+    boolean deleteData = false;
+    // 使用UriMatcher匹配URI，确定删除哪个表
+    switch (mMatcher.match(uri)) {
+        case URI_NOTE:
+            // 删除笔记数据，限制删除ID大于0的记录
+            selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
+            count = db.delete(TABLE.NOTE, selection, selectionArgs);
+            break;
+        case URI_NOTE_ITEM:
+            // 删除单个笔记项
+            id = uri.getPathSegments().get(1);
+            long noteId = Long.valueOf(id);
+            if (noteId <= 0) {
+                break;
+            }
+            count = db.delete(TABLE.NOTE,
+                    NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+            break;
+        case URI_DATA:
+            // 删除数据表中的记录
+            count = db.delete(TABLE.DATA, selection, selectionArgs);
+            deleteData = true;
+            break;
+        case URI_DATA_ITEM:
+            // 删除单个数据项
+            id = uri.getPathSegments().get(1);
+            count = db.delete(TABLE.DATA,
+                    DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+            deleteData = true;
+            break;
+        default:
+            // 如果URI不匹配，则抛出异常
+            throw new IllegalArgumentException("Unknown URI " + uri);
+    }
+    // 如果删除了记录，通知变化
+    if (count > 0) {
+        if (deleteData) {
+            getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
+        }
+        getContext().getContentResolver().notifyChange(uri, null);
+    }
+    return count;
+}
+
+/**
+ * 实现ContentProvider接口的update方法，用于更新数据。
+ * @param uri 请求的URI，用于确定更新数据的表。
+ * @param values 包含要更新数据的ContentValues。
+ * @param selection 更新条件。
+ * @param selectionArgs 更新条件的参数。
+ * @return 更新的行数。
+ */
+@Override
+public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
+    int count = 0;
+    String id = null;
+    SQLiteDatabase db = mHelper.getWritableDatabase();
+    boolean updateData = false;
+    // 使用UriMatcher匹配URI，确定更新哪个表
+    switch (mMatcher.match(uri)) {
+        case URI_NOTE:
+            // 更新笔记数据，增加版本号
+            increaseNoteVersion(-1, selection, selectionArgs);
+            count = db.update(TABLE.NOTE, values, selection, selectionArgs);
+            break;
+        case URI_NOTE_ITEM:
+            // 更新单个笔记项
+            id = uri.getPathSegments().get(1);
+            increaseNoteVersion(Long.valueOf(id), selection, selectionArgs);
+            count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+                    + parseSelection(selection), selectionArgs);
+            break;
+        case URI_DATA:
+            // 更新数据表中的记录
+            count = db.update(TABLE.DATA, values, selection, selectionArgs);
+            updateData = true;
+            break;
+        case URI_DATA_ITEM:
+            // 更新单个数据项
+            id = uri.getPathSegments().get(1);
+            count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
+                    + parseSelection(selection), selectionArgs);
+            updateData = true;
+            break;
+        default:
+            // 如果URI不匹配，则抛出异常
+            throw new IllegalArgumentException("Unknown URI " + uri);
+    }
+    // 如果更新了记录，通知变化
+    if (count > 0) {
+        if (updateData) {
+            getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
+        }
+        getContext().getContentResolver().notifyChange(uri, null);
+    }
+    return count;
+}
+
+/**
+ * 解析选择条件，添加AND前缀。
+ * @param selection 选择条件。
+ * @return 处理后的选择条件。
+ */
+private String parseSelection(String selection) {
+    return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
+}
+
+/**
+ * 增加笔记的版本号。
+ * @param id 笔记ID，-1表示更新所有匹配的记录。
+ * @param selection 更新条件。
+ * @param selectionArgs 更新条件的参数。
+ */
+private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
+    // 构建SQL语句，增加版本号
+    StringBuilder sql = new StringBuilder(120);
+    sql.append("UPDATE ");
+    sql.append(TABLE.NOTE);
+    sql.append(" SET ");
+    sql.append(NoteColumns.VERSION);
+    sql.append("=" + NoteColumns.VERSION + "+1 ");
+
+    if (id > 0 || !TextUtils.isEmpty(selection)) {
+        sql.append(" WHERE ");
+    }
+    if (id > 0) {
+        sql.append(NoteColumns.ID + "=" + String.valueOf(id));
+    }
+    if (!TextUtils.isEmpty(selection)) {
+        String selectString = id > 0 ? parseSelection(selection) : selection;
+        for (String args : selectionArgs) {
+            selectString = selectString.replaceFirst("\\?", args);
+        }
+        sql.append(selectString);
+    }
+
+    // 执行SQL语句
+    mHelper.getWritableDatabase().execSQL(sql.toString());
+}
+
+/**
+ * 实现ContentProvider接口的getType方法，用于获取数据类型。
+ * @param uri 请求的URI。
+ * @return 数据类型，此方法未实现返回null。
+ */
+@Override
+public String getType(Uri uri) {
+    // TODO Auto-generated method stub
+    return null;
+    }
+}