陈念焯注释

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;
+    // URI匹配代码常量
-    private static final int URI_NOTE_ITEM       = 2;
+    private static final int URI_NOTE            = 1;  // 笔记集合操作
-    private static final int URI_DATA            = 3;
+    private static final int URI_NOTE_ITEM       = 2;  // 单条笔记操作
-    private static final int URI_DATA_ITEM       = 4;
+    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;
+    private static final int URI_SEARCH          = 5;  // 搜索操作
-    private static final int URI_SEARCH_SUGGEST  = 6;
+    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,
+     * 搜索结果的投影(列)定义
-     * we will trim '\n' and white space in order to show more information.
+     * 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
+                 * ID小于0的是系统文件夹，不允许删除
-                 * trash
                  */
                 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;
     }
-
 }