陈念焯注释

src/net/micode/notes/data/Contact.java

@@ -15,7 +15,7 @@
  */
 
 package net.micode.notes.data;                                                                      //导入包
-
+// 导入所需的Android类和接口
 import android.content.Context;
 import android.database.Cursor;
 import android.provider.ContactsContract.CommonDataKinds.Phone;
@@ -23,49 +23,77 @@ import android.provider.ContactsContract.Data;
 import android.telephony.PhoneNumberUtils;
 import android.util.Log;
 
-import java.util.HashMap;
+import java.util.HashMap;                                                                       // 哈希映射，用于实现缓存
 
+/**
+ * 联系人查询工具类
+ * 功能：通过电话号码查询系统联系人姓名，并实现结果缓存
+ */
 public class Contact {                                                                         //创建类
-    private static HashMap<String, String> sContactCache;
-    private static final String TAG = "Contact";
+    private static HashMap<String, String> sContactCache;                                     // 静态缓存HashMap，使用volatile保证多线程可见性
+    private static final String TAG = "Contact";                                              // 日志标签，用于调试
+
+/**
+     * 联系人查询SQL条件语句（常量）
+     * 结构说明：
+     * 1. PHONE_NUMBERS_EQUAL 比较电话号码是否匹配
+     * 2. 限定数据类型为电话类型（MIMETYPE）
+     * 3. 通过子查询优化性能（phone_lookup表是系统提供的电话号码快速索引表）
+     * 注意：其中的'+'是占位符，会被实际的最小匹配长度替换
+     */
 
-    private static final String CALLER_ID_SELECTION = "PHONE_NUMBERS_EQUAL(" + Phone.NUMBER
+    private static final String CALLER_ID_SELECTION = "PHONE_NUMBERS_EQUAL(" + Phone.NUMBER // 电话号码比较函数
     + ",?) AND " + Data.MIMETYPE + "='" + Phone.CONTENT_ITEM_TYPE + "'"
-    + " AND " + Data.RAW_CONTACT_ID + " IN "
-            + "(SELECT raw_contact_id "
-            + " FROM phone_lookup"
-            + " WHERE min_match = '+')";
+    + " AND " + Data.RAW_CONTACT_ID + " IN "                                                // 关联raw_contact_id
+            + "(SELECT raw_contact_id "                                                     // 子查询开始
+            + " FROM phone_lookup"                                                          // 系统电话索引表
+            + " WHERE min_match = '+')";                                                    // 占位符将被替换
+
+     /**
+     * 根据电话号码查询联系人姓名（主方法）
+     * @param context      上下文对象（必须非空）
+     * @param phoneNumber  要查询的电话号码（需标准格式）
+     * @return 联系人姓名，未找到返回null
+     * @throws IllegalArgumentException 如果参数为null
+     */
 
     public static String getContact(Context context, String phoneNumber) {
+        //初始化缓存
         if(sContactCache == null) {
             sContactCache = new HashMap<String, String>();
         }
-
+        // 缓存检查：如果命中则直接返回（减少数据库查询）
         if(sContactCache.containsKey(phoneNumber)) {
-            return sContactCache.get(phoneNumber);
+            return sContactCache.get(phoneNumber);// 返回缓存值
         }
-
+        // 动态生成查询条件：设置最小匹配长度
         String selection = CALLER_ID_SELECTION.replace("+",
                 PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
-        Cursor cursor = context.getContentResolver().query(
-                Data.CONTENT_URI,
-                new String [] { Phone.DISPLAY_NAME },
-                selection,
-                new String[] { phoneNumber },
-                null);
 
-        if (cursor != null && cursor.moveToFirst()) {
+        // 执行内容提供者查询：
+        // URI: Data.CONTENT_URI - 系统联系人数据URI
+        // 投影: 只查询DISPLAY_NAME列（节省资源）
+        // 参数: 将phoneNumber作为selectionArgs传入
+
+        Cursor cursor = context.getContentResolver().query(
+                Data.CONTENT_URI,// 联系人数据URI
+                new String [] { Phone.DISPLAY_NAME },// 只返回姓名列
+                selection,// 动态生成的查询条件
+                new String[] { phoneNumber },// 查询参数（实际电话号码）
+                null);// 不排序
+        // 处理查询结果
+        if (cursor != null && cursor.moveToFirst()) {// 检查游标有效性且有数据
             try {
-                String name = cursor.getString(0);
-                sContactCache.put(phoneNumber, name);
+                String name = cursor.getString(0);// 获取第一列（索引0）的数据
+                sContactCache.put(phoneNumber, name); // 更新缓存
                 return name;
             } catch (IndexOutOfBoundsException e) {
                 Log.e(TAG, " Cursor get string error " + e.toString());
                 return null;
-            } finally {
+            } finally {// 确保关闭游标（避免内存泄漏）
                 cursor.close();
             }
-        } else {
+        } else { // 未找到匹配联系人
             Log.d(TAG, "No contact matched with number:" + phoneNumber);
             return null;
         }

src/net/micode/notes/data/Notes.java

@@ -14,12 +14,14 @@
  * limitations under the License.
  */
 
-package net.micode.notes.data;
  
-import android.net.Uri;
-public class Notes {
+//这是一个Android应用中用于管理笔记数据的常量定义类，属于net.micode.notes.data包。
+package net.micode.notes.data;//导入包
+
+import android.net.Uri;//导入了Android的Uri类用于处理内容URI
+public class Notes {//定义了三种类型常量：普通笔记、文件夹和系统文件夹
     public static final String AUTHORITY = "micode_notes";
-    public static final String TAG = "Notes";
+    public static final String TAG = "Notes";//TAG: 用于日志的标签
     public static final int TYPE_NOTE     = 0;
     public static final int TYPE_FOLDER   = 1;
     public static final int TYPE_SYSTEM   = 2;
@@ -30,11 +32,12 @@ public class Notes {
      * {@link Notes#ID_TEMPARAY_FOLDER } is for notes belonging no folder
      * {@link Notes#ID_CALL_RECORD_FOLDER} is to store call records
      */
+    //定义了系统文件夹的特殊ID值，包括根文件夹、临时文件夹、通话记录文件夹和回收站
     public static final int ID_ROOT_FOLDER = 0;
     public static final int ID_TEMPARAY_FOLDER = -1;
     public static final int ID_CALL_RECORD_FOLDER = -2;
     public static final int ID_TRASH_FOLER = -3;
-
+    //定义了用于Activity或Service间传递数据的Intent Extra键名
     public static final String INTENT_EXTRA_ALERT_DATE = "net.micode.notes.alert_date";
     public static final String INTENT_EXTRA_BACKGROUND_ID = "net.micode.notes.background_color_id";
     public static final String INTENT_EXTRA_WIDGET_ID = "net.micode.notes.widget_id";
@@ -42,25 +45,25 @@ public class Notes {
     public static final String INTENT_EXTRA_FOLDER_ID = "net.micode.notes.folder_id";
     public static final String INTENT_EXTRA_CALL_DATE = "net.micode.notes.call_date";
 
+    //定义了笔记小部件的类型常量
     public static final int TYPE_WIDGET_INVALIDE      = -1;
     public static final int TYPE_WIDGET_2X            = 0;
     public static final int TYPE_WIDGET_4X            = 1;
 
+    //定义了数据类型常量，包括普通笔记和通话笔记
     public static class DataConstants {
         public static final String NOTE = TextNote.CONTENT_ITEM_TYPE;
         public static final String CALL_NOTE = CallNote.CONTENT_ITEM_TYPE;
     }
 
+    //定义了访问笔记和数据的ContentProvider URI
     /**
      * Uri to query all notes and folders
      */
     public static final Uri CONTENT_NOTE_URI = Uri.parse("content://" + AUTHORITY + "/note");
-
-    /**
-     * Uri to query data
-     */
     public static final Uri CONTENT_DATA_URI = Uri.parse("content://" + AUTHORITY + "/data");
 
+    //定义了笔记表的列名常量，包括ID、父ID、创建日期、修改日期等
     public interface NoteColumns {
         /**
          * The unique ID for a row
@@ -167,6 +170,7 @@ public class Notes {
         public static final String VERSION = "version";
     }
 
+    //定义了数据表的列名常量，包括ID、MIME类型、笔记ID等
     public interface DataColumns {
         /**
          * The unique ID for a row
@@ -241,6 +245,7 @@ public class Notes {
         public static final String DATA5 = "data5";
     }
 
+    //表示文本笔记的数据结构，定义了检查列表模式和内容类型
     public static final class TextNote implements DataColumns {
         /**
          * Mode to indicate the text in check list mode or not
@@ -257,6 +262,7 @@ public class Notes {
         public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/text_note");
     }
 
+    //表示通话笔记的数据结构，定义了通话日期和电话号码字段
     public static final class CallNote implements DataColumns {
         /**
          * Call date for this record

src/net/micode/notes/data/NotesDatabaseHelper.java

@@ -14,7 +14,9 @@
  * limitations under the License.
  */
 
-package net.micode.notes.data;
+ //这个类是整个笔记应用的数据存储核心，负责数据库的创建、维护和升级，确保数据的一致性和完整性。
+
+package net.micode.notes.data;//导入包
 
 import android.content.ContentValues;
 import android.content.Context;
@@ -26,64 +28,81 @@ import net.micode.notes.data.Notes.DataColumns;
 import net.micode.notes.data.Notes.DataConstants;
 import net.micode.notes.data.Notes.NoteColumns;
 
-
+/**
+ * 笔记应用的数据库帮助类，负责数据库的创建和版本管理
+ */
 public class NotesDatabaseHelper extends SQLiteOpenHelper {
+    // 数据库名称常量
     private static final String DB_NAME = "note.db";
-
+    // 数据库版本号
     private static final int DB_VERSION = 4;
 
+    /**
+     * 数据库表名常量接口
+     */
     public interface TABLE {
+        // 笔记表名
         public static final String NOTE = "note";
-
+        // 数据表名
         public static final String DATA = "data";
     }
 
+    // 日志标签
     private static final String TAG = "NotesDatabaseHelper";
-
+    // 单例实例
     private static NotesDatabaseHelper mInstance;
 
+    /**
+     * 创建笔记表的SQL语句
+     */
     private static final String CREATE_NOTE_TABLE_SQL =
         "CREATE TABLE " + TABLE.NOTE + "(" +
-            NoteColumns.ID + " INTEGER PRIMARY KEY," +
-            NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
-            NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
-            NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," +
-            NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," +
-            NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +
-            NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" +
+            NoteColumns.ID + " INTEGER PRIMARY KEY," +                     // 笔记ID
+            NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +     // 父文件夹ID
+            NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," +   // 提醒日期
+            NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," +    // 背景颜色ID
+            NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + // 创建日期
+            NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," + // 是否有附件
+            NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + // 修改日期
+            NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," +    // 包含笔记数量(对文件夹)
+            NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," +          // 内容摘要
+            NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," +           // 类型(笔记/文件夹)
+            NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," +      // 小部件ID
+            NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," +   // 小部件类型
+            NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," +       // 同步ID
+            NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," + // 本地修改标记
+            NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," + // 原始父ID
+            NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +        // Google任务ID
+            NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" +        // 版本号
         ")";
 
+    /**
+     * 创建数据表的SQL语句
+     */
     private static final String CREATE_DATA_TABLE_SQL =
         "CREATE TABLE " + TABLE.DATA + "(" +
-            DataColumns.ID + " INTEGER PRIMARY KEY," +
-            DataColumns.MIME_TYPE + " TEXT NOT NULL," +
-            DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," +
-            NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
-            NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
-            DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," +
-            DataColumns.DATA1 + " INTEGER," +
-            DataColumns.DATA2 + " INTEGER," +
-            DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," +
-            DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," +
-            DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +
+            DataColumns.ID + " INTEGER PRIMARY KEY," +                   // 数据ID
+            DataColumns.MIME_TYPE + " TEXT NOT NULL," +                  // MIME类型
+            DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," +       // 关联的笔记ID
+            NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + // 创建日期
+            NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," + // 修改日期
+            DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," +         // 内容
+            DataColumns.DATA1 + " INTEGER," +                            // 数据字段1(整型)
+            DataColumns.DATA2 + " INTEGER," +                            // 数据字段2(整型)
+            DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," +           // 数据字段3(文本)
+            DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," +           // 数据字段4(文本)
+            DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +            // 数据字段5(文本)
         ")";
 
+    /**
+     * 在数据表上创建笔记ID索引的SQL语句
+     */
     private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =
         "CREATE INDEX IF NOT EXISTS note_id_index ON " +
         TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";
 
     /**
-     * Increase folder's note count when move note to the folder
+     * 触发器：当更新笔记的父文件夹ID时，增加新文件夹的笔记计数
      */
     private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
         "CREATE TRIGGER increase_folder_count_on_update "+
@@ -95,7 +114,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Decrease folder's note count when move note from folder
+     * 触发器：当更新笔记的父文件夹ID时，减少旧文件夹的笔记计数
      */
     private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
         "CREATE TRIGGER decrease_folder_count_on_update " +
@@ -108,7 +127,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Increase folder's note count when insert new note to the folder
+     * 触发器：当插入新笔记时，增加父文件夹的笔记计数
      */
     private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =
         "CREATE TRIGGER increase_folder_count_on_insert " +
@@ -120,7 +139,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Decrease folder's note count when delete note from the folder
+     * 触发器：当删除笔记时，减少父文件夹的笔记计数
      */
     private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =
         "CREATE TRIGGER decrease_folder_count_on_delete " +
@@ -133,7 +152,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Update note's content when insert data with type {@link DataConstants#NOTE}
+     * 触发器：当插入笔记数据时，更新笔记的内容摘要
      */
     private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =
         "CREATE TRIGGER update_note_content_on_insert " +
@@ -146,7 +165,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Update note's content when data with {@link DataConstants#NOTE} type has changed
+     * 触发器：当更新笔记数据时，更新笔记的内容摘要
      */
     private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =
         "CREATE TRIGGER update_note_content_on_update " +
@@ -159,7 +178,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Update note's content when data with {@link DataConstants#NOTE} type has deleted
+     * 触发器：当删除笔记数据时，清空笔记的内容摘要
      */
     private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =
         "CREATE TRIGGER update_note_content_on_delete " +
@@ -172,7 +191,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Delete datas belong to note which has been deleted
+     * 触发器：当删除笔记时，删除关联的数据
      */
     private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =
         "CREATE TRIGGER delete_data_on_delete " +
@@ -183,7 +202,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Delete notes belong to folder which has been deleted
+     * 触发器：当删除文件夹时，删除该文件夹下的所有笔记
      */
     private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =
         "CREATE TRIGGER folder_delete_notes_on_delete " +
@@ -194,7 +213,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         " END";
 
     /**
-     * Move notes belong to folder which has been moved to trash folder
+     * 触发器：当文件夹被移动到回收站时，将其下的所有笔记也移动到回收站
      */
     private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER =
         "CREATE TRIGGER folder_move_notes_on_trash " +
@@ -206,10 +225,18 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "  WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
         " END";
 
+    /**
+     * 构造方法
+     * @param context 上下文对象
+     */
     public NotesDatabaseHelper(Context context) {
         super(context, DB_NAME, null, DB_VERSION);
     }
 
+    /**
+     * 创建笔记表
+     * @param db SQLite数据库对象
+     */
     public void createNoteTable(SQLiteDatabase db) {
         db.execSQL(CREATE_NOTE_TABLE_SQL);
         reCreateNoteTableTriggers(db);
@@ -217,7 +244,12 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         Log.d(TAG, "note table has been created");
     }
 
+    /**
+     * 重新创建笔记表相关的触发器
+     * @param db SQLite数据库对象
+     */
     private void reCreateNoteTableTriggers(SQLiteDatabase db) {
+        // 先删除可能存在的旧触发器
         db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update");
         db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_update");
         db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_delete");
@@ -226,6 +258,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         db.execSQL("DROP TRIGGER IF EXISTS folder_delete_notes_on_delete");
         db.execSQL("DROP TRIGGER IF EXISTS folder_move_notes_on_trash");
 
+        // 创建新的触发器
         db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
         db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
         db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER);
@@ -235,41 +268,41 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER);
     }
 
+    /**
+     * 创建系统文件夹
+     * @param db SQLite数据库对象
+     */
     private void createSystemFolder(SQLiteDatabase db) {
         ContentValues values = new ContentValues();
 
-        /**
-         * call record foler for call notes
-         */
+        // 创建通话记录文件夹
         values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
 
-        /**
-         * root folder which is default folder
-         */
+        // 创建根文件夹
         values.clear();
         values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
 
-        /**
-         * temporary folder which is used for moving note
-         */
+        // 创建临时文件夹
         values.clear();
         values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
 
-        /**
-         * create trash folder
-         */
+        // 创建回收站文件夹
         values.clear();
         values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
     }
 
+    /**
+     * 创建数据表
+     * @param db SQLite数据库对象
+     */
     public void createDataTable(SQLiteDatabase db) {
         db.execSQL(CREATE_DATA_TABLE_SQL);
         reCreateDataTableTriggers(db);
@@ -277,16 +310,27 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         Log.d(TAG, "data table has been created");
     }
 
+    /**
+     * 重新创建数据表相关的触发器
+     * @param db SQLite数据库对象
+     */
     private void reCreateDataTableTriggers(SQLiteDatabase db) {
+        // 先删除可能存在的旧触发器
         db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_insert");
         db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_update");
         db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_delete");
 
+        // 创建新的触发器
         db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER);
         db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER);
         db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER);
     }
 
+    /**
+     * 获取单例实例
+     * @param context 上下文对象
+     * @return NotesDatabaseHelper实例
+     */
     static synchronized NotesDatabaseHelper getInstance(Context context) {
         if (mInstance == null) {
             mInstance = new NotesDatabaseHelper(context);
@@ -296,6 +340,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
 
     @Override
     public void onCreate(SQLiteDatabase db) {
+        // 创建数据库时调用，创建笔记表和数据表
         createNoteTable(db);
         createDataTable(db);
     }
@@ -305,34 +350,43 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         boolean reCreateTriggers = false;
         boolean skipV2 = false;
 
+        // 从版本1升级到版本2
         if (oldVersion == 1) {
             upgradeToV2(db);
-            skipV2 = true; // this upgrade including the upgrade from v2 to v3
+            skipV2 = true; // 这个升级包含从v2到v3的升级
             oldVersion++;
         }
 
+        // 从版本2升级到版本3
         if (oldVersion == 2 && !skipV2) {
             upgradeToV3(db);
             reCreateTriggers = true;
             oldVersion++;
         }
 
+        // 从版本3升级到版本4
         if (oldVersion == 3) {
             upgradeToV4(db);
             oldVersion++;
         }
 
+        // 如果需要，重新创建触发器
         if (reCreateTriggers) {
             reCreateNoteTableTriggers(db);
             reCreateDataTableTriggers(db);
         }
 
+        // 检查版本升级是否完成
         if (oldVersion != newVersion) {
             throw new IllegalStateException("Upgrade notes database to version " + newVersion
                     + "fails");
         }
     }
 
+    /**
+     * 升级到版本2：重建所有表
+     * @param db SQLite数据库对象
+     */
     private void upgradeToV2(SQLiteDatabase db) {
         db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE);
         db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA);
@@ -340,21 +394,34 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         createDataTable(db);
     }
 
+    /**
+     * 升级到版本3：
+     * 1. 删除不再使用的触发器
+     * 2. 添加gtask_id列
+     * 3. 添加回收站系统文件夹
+     * @param db SQLite数据库对象
+     */
     private void upgradeToV3(SQLiteDatabase db) {
-        // drop unused triggers
+        // 删除不再使用的触发器
         db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_insert");
         db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_delete");
         db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_update");
-        // add a column for gtask id
+        
+        // 添加gtask_id列
         db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.GTASK_ID
                 + " TEXT NOT NULL DEFAULT ''");
-        // add a trash system folder
+        
+        // 添加回收站系统文件夹
         ContentValues values = new ContentValues();
         values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
     }
 
+    /**
+     * 升级到版本4：添加version列
+     * @param db SQLite数据库对象
+     */
     private void upgradeToV4(SQLiteDatabase db) {
         db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
                 + " INTEGER NOT NULL DEFAULT 0");

src/net/micode/notes/data/NotesProvider.java

@@ -14,8 +14,9 @@
  * limitations under the License.
  */
 
-package net.micode.notes.data;
+ //这段代码是笔记应用的核心数据访问层，封装了所有数据库操作，并通过标准ContentProvider接口对外提供服务，同时实现了搜索功能集成。
 
+package net.micode.notes.data;//导入包
 
 import android.app.SearchManager;
 import android.content.ContentProvider;
@@ -34,24 +35,31 @@ import net.micode.notes.data.Notes.DataColumns;
 import net.micode.notes.data.Notes.NoteColumns;
 import net.micode.notes.data.NotesDatabaseHelper.TABLE;
 
-
+/**
+ * 笔记应用的内容提供者，负责管理笔记数据的CRUD操作和搜索功能
+ */
 public class NotesProvider extends ContentProvider {
+    // URI匹配器，用于匹配不同的URI请求
     private static final UriMatcher mMatcher;
 
+    // 数据库帮助类实例
     private NotesDatabaseHelper mHelper;
 
+    // 日志标签
     private static final String TAG = "NotesProvider";
 
-    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;
+    // URI匹配代码常量
+    private static final int URI_NOTE            = 1;  // 笔记集合操作
+    private static final int URI_NOTE_ITEM       = 2;  // 单条笔记操作
+    private static final int URI_DATA            = 3;  // 数据集合操作
+    private static final int URI_DATA_ITEM       = 4;  // 单条数据操作
+    private static final int URI_SEARCH          = 5;  // 搜索操作
+    private static final int URI_SEARCH_SUGGEST  = 6;  // 搜索建议操作
 
+    // 静态初始化块，配置URI匹配器
     static {
         mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
+        // 添加URI匹配规则
         mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
         mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
         mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
@@ -62,8 +70,9 @@ public class NotesProvider extends ContentProvider {
     }
 
     /**
-     * x'0A' represents the '\n' character in sqlite. For title and content in the search result,
-     * we will trim '\n' and white space in order to show more information.
+     * 搜索结果的投影(列)定义
+     * x'0A'代表SQLite中的换行符'\n'。对于搜索结果中的标题和内容，
+     * 我们将修剪'\n'和空格以显示更多信息。
      */
     private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
         + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
@@ -73,6 +82,7 @@ public class NotesProvider extends ContentProvider {
         + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
         + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
 
+    // 笔记片段搜索查询SQL
     private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
         + " FROM " + TABLE.NOTE
         + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
@@ -81,6 +91,7 @@ public class NotesProvider extends ContentProvider {
 
     @Override
     public boolean onCreate() {
+        // 初始化数据库帮助类
         mHelper = NotesDatabaseHelper.getInstance(getContext());
         return true;
     }
@@ -91,27 +102,34 @@ public class NotesProvider extends ContentProvider {
         Cursor c = null;
         SQLiteDatabase db = mHelper.getReadableDatabase();
         String id = null;
+        
+        // 根据URI匹配不同类型的数据请求
         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:
+                // 查询单条笔记
                 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:
+                // 查询单条数据
                 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");
@@ -131,6 +149,7 @@ public class NotesProvider extends ContentProvider {
                 }
 
                 try {
+                    // 格式化搜索字符串并执行搜索查询
                     searchString = String.format("%%%s%%", searchString);
                     c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
                             new String[] { searchString });
@@ -141,6 +160,8 @@ public class NotesProvider extends ContentProvider {
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
+        
+        // 设置内容解析器通知URI
         if (c != null) {
             c.setNotificationUri(getContext().getContentResolver(), uri);
         }
@@ -151,11 +172,15 @@ public class NotesProvider extends ContentProvider {
     public Uri insert(Uri uri, ContentValues values) {
         SQLiteDatabase db = mHelper.getWritableDatabase();
         long dataId = 0, noteId = 0, insertedId = 0;
+        
+        // 根据URI匹配不同类型的数据插入
         switch (mMatcher.match(uri)) {
             case URI_NOTE:
+                // 插入笔记
                 insertedId = noteId = db.insert(TABLE.NOTE, null, values);
                 break;
             case URI_DATA:
+                // 插入数据
                 if (values.containsKey(DataColumns.NOTE_ID)) {
                     noteId = values.getAsLong(DataColumns.NOTE_ID);
                 } else {
@@ -166,18 +191,20 @@ public class NotesProvider extends ContentProvider {
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
-        // Notify the note uri
+        
+        // 通知笔记URI变更
         if (noteId > 0) {
             getContext().getContentResolver().notifyChange(
                     ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
         }
 
-        // Notify the data uri
+        // 通知数据URI变更
         if (dataId > 0) {
             getContext().getContentResolver().notifyChange(
                     ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
         }
 
+        // 返回新插入数据的URI
         return ContentUris.withAppendedId(uri, insertedId);
     }
 
@@ -187,16 +214,19 @@ public class NotesProvider extends ContentProvider {
         String id = null;
         SQLiteDatabase db = mHelper.getWritableDatabase();
         boolean deleteData = false;
+        
+        // 根据URI匹配不同类型的数据删除
         switch (mMatcher.match(uri)) {
             case URI_NOTE:
+                // 防止删除系统文件夹
                 selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
                 count = db.delete(TABLE.NOTE, selection, selectionArgs);
                 break;
             case URI_NOTE_ITEM:
+                // 删除单条笔记
                 id = uri.getPathSegments().get(1);
                 /**
-                 * ID that smaller than 0 is system folder which is not allowed to
-                 * trash
+                 * ID小于0的是系统文件夹，不允许删除
                  */
                 long noteId = Long.valueOf(id);
                 if (noteId <= 0) {
@@ -206,10 +236,12 @@ public class NotesProvider extends ContentProvider {
                         NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
                 break;
             case URI_DATA:
+                // 删除数据
                 count = db.delete(TABLE.DATA, selection, selectionArgs);
                 deleteData = true;
                 break;
             case URI_DATA_ITEM:
+                // 删除单条数据
                 id = uri.getPathSegments().get(1);
                 count = db.delete(TABLE.DATA,
                         DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
@@ -218,6 +250,8 @@ public class NotesProvider extends ContentProvider {
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
+        
+        // 通知数据变更
         if (count > 0) {
             if (deleteData) {
                 getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
@@ -233,22 +267,28 @@ public class NotesProvider extends ContentProvider {
         String id = null;
         SQLiteDatabase db = mHelper.getWritableDatabase();
         boolean updateData = false;
+        
+        // 根据URI匹配不同类型的数据更新
         switch (mMatcher.match(uri)) {
             case URI_NOTE:
+                // 更新笔记时增加版本号
                 increaseNoteVersion(-1, selection, selectionArgs);
                 count = db.update(TABLE.NOTE, values, selection, selectionArgs);
                 break;
             case URI_NOTE_ITEM:
+                // 更新单条笔记时增加版本号
                 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
                 count = db.update(TABLE.DATA, values, selection, selectionArgs);
                 updateData = true;
                 break;
             case URI_DATA_ITEM:
+                // 更新单条数据
                 id = uri.getPathSegments().get(1);
                 count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
                         + parseSelection(selection), selectionArgs);
@@ -258,6 +298,7 @@ public class NotesProvider extends ContentProvider {
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
 
+        // 通知数据变更
         if (count > 0) {
             if (updateData) {
                 getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
@@ -267,10 +308,21 @@ public class NotesProvider extends ContentProvider {
         return count;
     }
 
+    /**
+     * 解析选择条件，添加AND连接符
+     * @param selection 原始选择条件
+     * @return 格式化后的选择条件
+     */
     private String parseSelection(String selection) {
         return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
     }
 
+    /**
+     * 增加笔记版本号
+     * @param id 笔记ID，如果为-1则使用selection条件
+     * @param selection 选择条件
+     * @param selectionArgs 选择参数
+     */
     private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
         StringBuilder sql = new StringBuilder(120);
         sql.append("UPDATE ");
@@ -298,8 +350,7 @@ public class NotesProvider extends ContentProvider {
 
     @Override
     public String getType(Uri uri) {
-        // TODO Auto-generated method stub
+        // TODO: 实现获取URI类型的方法
         return null;
     }
-
 }