diff --git a/src/net/micode/notes/tool/DataUtils.java b/src/net/micode/notes/tool/DataUtils.java
index 2a14982..4163d69 100644
--- a/src/net/micode/notes/tool/DataUtils.java
+++ b/src/net/micode/notes/tool/DataUtils.java
@@ -50,7 +50,7 @@ public class DataUtils {
         ArrayList<ContentProviderOperation> operationList = new ArrayList<ContentProviderOperation>();
         for (long id : ids) {
             if(id == Notes.ID_ROOT_FOLDER) {
-                Log.e(TAG, "Don't delete system folder root");
+                Log.e(TAG, "Don't delete system folder root"); //如果发现是根文件夹，则不删除
                 continue;
             }
             ContentProviderOperation.Builder builder = ContentProviderOperation
@@ -58,7 +58,7 @@ public class DataUtils {
             operationList.add(builder.build());
         }
         try {
-            ContentProviderResult[] results = resolver.applyBatch(Notes.AUTHORITY, operationList);
+            ContentProviderResult[] results = resolver.applyBatch(Notes.AUTHORITY, operationList);//数据库事务，数据库事务是由一组数据库操作序列组成，事务作为一个整体被执行
             if (results == null || results.length == 0 || results[0] == null) {
                 Log.d(TAG, "delete notes failed, ids:" + ids.toString());
                 return false;
@@ -93,7 +93,8 @@ public class DataUtils {
                     .newUpdate(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, id));
             builder.withValue(NoteColumns.PARENT_ID, folderId);
             builder.withValue(NoteColumns.LOCAL_MODIFIED, 1);
-            operationList.add(builder.build());
+            operationList.add(builder.build());//将ids里包含的每一列的数据逐次加入到operationList中，等待最后的批量处理
+
         }
 
         try {
@@ -119,7 +120,7 @@ public class DataUtils {
                 new String[] { "COUNT(*)" },
                 NoteColumns.TYPE + "=? AND " + NoteColumns.PARENT_ID + "<>?",
                 new String[] { String.valueOf(Notes.TYPE_FOLDER), String.valueOf(Notes.ID_TRASH_FOLER)},
-                null);
+                null);//筛选条件：源文件不为trash folder
 
         int count = 0;
         if(cursor != null) {
@@ -141,11 +142,11 @@ public class DataUtils {
                 null,
                 NoteColumns.TYPE + "=? AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER,
                 new String [] {String.valueOf(type)},
-                null);
+                null);//查询条件：type符合，且不属于垃圾文件夹
 
         boolean exist = false;
         if (cursor != null) {
-            if (cursor.getCount() > 0) {
+            if (cursor.getCount() > 0) {//用getcount函数判断cursor是否为空
                 exist = true;
             }
             cursor.close();
@@ -171,7 +172,7 @@ public class DataUtils {
         Cursor cursor = resolver.query(ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId),
                 null, null, null, null);
 
-        boolean exist = false;
+        boolean exist = false;//通过名字查询文件是否存在
         if (cursor != null) {
             if (cursor.getCount() > 0) {
                 exist = true;
@@ -202,7 +203,7 @@ public class DataUtils {
                 new String[] { NoteColumns.WIDGET_ID, NoteColumns.WIDGET_TYPE },
                 NoteColumns.PARENT_ID + "=?",
                 new String[] { String.valueOf(folderId) },
-                null);
+                null);//查询条件：父ID是传入的folderId;
 
         HashSet<AppWidgetAttribute> set = null;
         if (c != null) {
@@ -211,13 +212,13 @@ public class DataUtils {
                 do {
                     try {
                         AppWidgetAttribute widget = new AppWidgetAttribute();
-                        widget.widgetId = c.getInt(0);
-                        widget.widgetType = c.getInt(1);
+                        widget.widgetId = c.getInt(0);//0对应的NoteColumns.WIDGET_ID
+                        widget.widgetType = c.getInt(1);//1对应的NoteColumns.WIDGET_TYPE
                         set.add(widget);
                     } catch (IndexOutOfBoundsException e) {
                         Log.e(TAG, e.toString());
                     }
-                } while (c.moveToNext());
+                } while (c.moveToNext());//查询下一条
             }
             c.close();
         }
@@ -229,11 +230,12 @@ public class DataUtils {
                 new String [] { CallNote.PHONE_NUMBER },
                 CallNote.NOTE_ID + "=? AND " + CallNote.MIME_TYPE + "=?",
                 new String [] { String.valueOf(noteId), CallNote.CONTENT_ITEM_TYPE },
-                null);
+                null); //通过数据库操作，查询条件是（callDate和phoneNumber匹配传入参数的值）
+
 
         if (cursor != null && cursor.moveToFirst()) {
             try {
-                return cursor.getString(0);
+                return cursor.getString(0);//0对应的CallNote.NOTE_ID
             } catch (IndexOutOfBoundsException e) {
                 Log.e(TAG, "Get call number fails " + e.toString());
             } finally {
@@ -249,7 +251,7 @@ public class DataUtils {
                 CallNote.CALL_DATE + "=? AND " + CallNote.MIME_TYPE + "=? AND PHONE_NUMBERS_EQUAL("
                 + CallNote.PHONE_NUMBER + ",?)",
                 new String [] { String.valueOf(callDate), CallNote.CONTENT_ITEM_TYPE, phoneNumber },
-                null);
+                null);//查询条件：noteId
 
         if (cursor != null) {
             if (cursor.moveToFirst()) {
@@ -282,7 +284,7 @@ public class DataUtils {
         throw new IllegalArgumentException("Note is not found with id: " + noteId);
     }
 
-    public static String getFormattedSnippet(String snippet) {
+    public static String getFormattedSnippet(String snippet) {//对字符串进行格式处理，将字符串两头的空格去掉，同时将换行符去掉
         if (snippet != null) {
             snippet = snippet.trim();
             int index = snippet.indexOf('\n');