diff --git a/src/data/Notes.java b/src/data/Notes.java
new file mode 100644
index 0000000..86806b8
--- /dev/null
+++ b/src/data/Notes.java
@@ -0,0 +1,305 @@
+
+
+package net.micode.notes.data;
+ 
+import android.content.ContentUris;
+import android.net.Uri;
+// Notes 类中定义了很多常量，这些常量大多是int型和string型
+public class Notes {
+    public static final String AUTHORITY = "micode_notes";
+    public static final String TAG = "Notes";
+    
+    //以下三个常量对NoteColumns.TYPE的值进行设置时会用到
+    public static final int TYPE_NOTE     = 0;
+    public static final int TYPE_FOLDER   = 1;
+    public static final int TYPE_SYSTEM   = 2;
+ 
+    /**
+     * Following IDs are system folders' identifiers
+     * {@link Notes#ID_ROOT_FOLDER } is default folder
+     * {@link Notes#ID_TEMPARAY_FOLDER } is for notes belonging no folder
+     * {@link Notes#ID_CALL_RECORD_FOLDER} is to store call records
+     */
+    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;
+ 
+    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";
+    public static final String INTENT_EXTRA_WIDGET_TYPE = 
+ 
+"net.micode.notes.widget_type";
+    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";
+ 
+    public static final int TYPE_WIDGET_INVALIDE      = -1;
+    public static final int TYPE_WIDGET_2X            = 0;
+    public static final int TYPE_WIDGET_4X            = 1;
+ 
+    public static class DataConstants {
+        public static final String NOTE = TextNote.CONTENT_ITEM_TYPE;
+        public static final String CALL_NOTE = CallNote.CONTENT_ITEM_TYPE;
+    }
+ 
+    /**
+     * Uri to query all notes and folders
+     */
+    public static final Uri CONTENT_NOTE_URI = Uri.parse("content://" + 
+ 
+AUTHORITY + "/note");//定义查询便签和文件夹的指针。
+ 
+//    public static final Uri my_URI = ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI , 10);
+   
+    /**
+     * Uri to query data
+     */
+    public static final Uri CONTENT_DATA_URI = Uri.parse("content://" + 
+ 
+AUTHORITY + "/data");//定义查找数据的指针。
+ 
+    // 定义NoteColumns的常量,用于后面创建数据库的表头
+    public interface NoteColumns {
+        /**
+         * The unique ID for a row
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String ID = "_id";
+ 
+        /**
+         * The parent's id for note or folder
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String PARENT_ID = "parent_id";//为什么会有parent_id
+ 
+        /**
+         * Created data for note or folder
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String CREATED_DATE = "created_date";
+ 
+        /**
+         * Latest modified date
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String MODIFIED_DATE = "modified_date";
+ 
+ 
+        /**
+         * Alert date
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String ALERTED_DATE = "alert_date";
+ 
+        /**
+         * Folder's name or text content of note
+         * <P> Type: TEXT </P>
+         */
+        public static final String SNIPPET = "snippet";
+ 
+        /**
+         * Note's widget id
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String WIDGET_ID = "widget_id";
+ 
+        /**
+         * Note's widget type
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String WIDGET_TYPE = "widget_type";
+ 
+        /**
+         * Note's background color's id
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String BG_COLOR_ID = "bg_color_id";
+ 
+        /**
+         * For text note, it doesn't has attachment, for multi-media
+         * note, it has at least one attachment
+         * <P> Type: INTEGER </P>
+         */
+        public static final String HAS_ATTACHMENT = "has_attachment";
+ 
+        /**
+         * Folder's count of notes
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String NOTES_COUNT = "notes_count";
+ 
+        /**
+         * The file type: folder or note
+         * <P> Type: INTEGER </P>
+         */
+        public static final String TYPE = "type";
+ 
+        /**
+         * The last sync id
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String SYNC_ID = "sync_id";//同步
+ 
+        /**
+         * Sign to indicate local modified or not
+         * <P> Type: INTEGER </P>
+         */
+        public static final String LOCAL_MODIFIED = "local_modified";
+ 
+        /**
+         * Original parent id before moving into temporary folder
+         * <P> Type : INTEGER </P>
+         */
+        public static final String ORIGIN_PARENT_ID = "origin_parent_id";
+ 
+        /**
+         * The gtask id
+         * <P> Type : TEXT </P>
+         */
+        public static final String GTASK_ID = "gtask_id";
+ 
+        /**
+         * The version code
+         * <P> Type : INTEGER (long) </P>
+         */
+        public static final String VERSION = "version";
+    }//这些常量主要是定义便签的属性的。
+ 
+    // 定义DataColumns的常量,用于后面创建数据库的表头
+    public interface DataColumns {
+        /**
+         * The unique ID for a row
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String ID = "_id";
+ 
+        /**
+         * The MIME type of the item represented by this row.
+         * <P> Type: Text </P>
+         */
+        public static final String MIME_TYPE = "mime_type";
+ 
+        /**
+         * The reference id to note that this data belongs to
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String NOTE_ID = "note_id";
+ 
+        /**
+         * Created data for note or folder
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String CREATED_DATE = "created_date";
+ 
+        /**
+         * Latest modified date
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String MODIFIED_DATE = "modified_date";
+ 
+        /**
+         * Data's content
+         * <P> Type: TEXT </P>
+         */
+        public static final String CONTENT = "content";
+ 
+ 
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, 
+used for
+         * integer data type
+         * <P> Type: INTEGER </P>
+         */
+        public static final String DATA1 = "data1";
+ 
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, 
+used for
+         * integer data type
+         * <P> Type: INTEGER </P>
+         */
+        public static final String DATA2 = "data2";
+ 
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, 
+used for
+         * TEXT data type
+         * <P> Type: TEXT </P>
+         */
+        public static final String DATA3 = "data3";
+ 
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, 
+used for
+         * TEXT data type
+         * <P> Type: TEXT </P>
+         */
+        public static final String DATA4 = "data4";
+ 
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, 
+used for
+         * TEXT data type
+         * <P> Type: TEXT </P>
+         */
+        public static final String DATA5 = "data5";
+    }//主要是定义存储便签内容数据的
+    public static final class TextNote implements DataColumns {
+        /**
+         * Mode to indicate the text in check list mode or not
+         * <P> Type: Integer 1:check list mode 0: normal mode </P>
+         */
+        public static final String MODE = DATA1;
+ 
+        public static final int MODE_CHECK_LIST = 1;
+ 
+        public static final String CONTENT_TYPE = 
+ 
+"vnd.android.cursor.dir/text_note";
+ 
+        public static final String CONTENT_ITEM_TYPE = 
+ 
+"vnd.android.cursor.item/text_note";
+ 
+        public static final Uri CONTENT_URI = Uri.parse("content://" + 
+ 
+AUTHORITY + "/text_note");
+    }//文本内容的数据结构
+ 
+    public static final class CallNote implements DataColumns {
+        /**
+         * Call date for this record
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String CALL_DATE = DATA1;
+ 
+        /**
+         * Phone number for this record
+         * <P> Type: TEXT </P>
+         */
+        public static final String PHONE_NUMBER = DATA3;
+ 
+        public static final String CONTENT_TYPE = 
+ 
+"vnd.android.cursor.dir/call_note";
+ 
+        public static final String CONTENT_ITEM_TYPE = 
+ 
+"vnd.android.cursor.item/call_note";
+ 
+        public static final Uri CONTENT_URI = Uri.parse("content://" + 
+ 
+AUTHORITY + "/call_note");
+    }//电话内容的数据结构
+}
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