添加注释

src/Notes-master1/app/src/main/java/net/micode/notes/data/NotesProvider.java

@@ -36,12 +36,16 @@ import net.micode.notes.data.NotesDatabaseHelper.TABLE;
 
 
 public class NotesProvider extends ContentProvider {
+    // 创建一个UriMatcher对象，用于匹配URI
     private static final UriMatcher mMatcher;
 
+    // 创建一个NotesDatabaseHelper对象，用于操作数据库
     private NotesDatabaseHelper mHelper;
 
+    // 创建一个TAG，用于标记日志
     private static final String TAG = "NotesProvider";
 
+    // 创建一个URI码，用于表示不同的URI
     private static final int URI_NOTE            = 1;
     private static final int URI_NOTE_ITEM       = 2;
     private static final int URI_DATA            = 3;
@@ -50,6 +54,7 @@ public class NotesProvider extends ContentProvider {
     private static final int URI_SEARCH          = 5;
     private static final int URI_SEARCH_SUGGEST  = 6;
 
+    // 静态初始化，创建一个UriMatcher对象，用于匹配URI
     static {
         mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
         mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
@@ -81,6 +86,7 @@ public class NotesProvider extends ContentProvider {
 
     @Override
     public boolean onCreate() {
+        // 获取NotesDatabaseHelper实例
         mHelper = NotesDatabaseHelper.getInstance(getContext());
         return true;
     }
@@ -88,99 +94,136 @@ public class NotesProvider extends ContentProvider {
     @Override
     public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
             String sortOrder) {
+        // 初始化游标
         Cursor c = null;
+        // 获取可读的数据库
         SQLiteDatabase db = mHelper.getReadableDatabase();
+        // 初始化id
         String id = null;
+        // 根据uri匹配模式
         switch (mMatcher.match(uri)) {
+            // 查询note表
             case URI_NOTE:
+                // 查询note表，并设置查询条件
                 c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
                         sortOrder);
                 break;
+            // 查询note表中的某一行
             case URI_NOTE_ITEM:
+                // 获取id
                 id = uri.getPathSegments().get(1);
+                // 查询note表，并设置查询条件
                 c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
                         + parseSelection(selection), selectionArgs, null, null, sortOrder);
                 break;
+            // 查询data表
             case URI_DATA:
+                // 查询data表，并设置查询条件
                 c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
                         sortOrder);
                 break;
+            // 查询data表中的某一行
             case URI_DATA_ITEM:
+                // 获取id
                 id = uri.getPathSegments().get(1);
+                // 查询data表，并设置查询条件
                 c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
                         + parseSelection(selection), selectionArgs, null, null, sortOrder);
                 break;
+            // 查询搜索建议
             case URI_SEARCH:
             case URI_SEARCH_SUGGEST:
+                // 检查排序，查询条件，查询参数是否有效
                 if (sortOrder != null || projection != null) {
                     throw new IllegalArgumentException(
                             "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
                 }
 
+                // 初始化搜索字符串
                 String searchString = null;
+                // 根据uri匹配模式，获取搜索字符串
                 if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
+                    // 如果uri中包含路径段，则获取路径段
                     if (uri.getPathSegments().size() > 1) {
                         searchString = uri.getPathSegments().get(1);
                     }
                 } else {
+                    // 从uri中获取查询参数
                     searchString = uri.getQueryParameter("pattern");
                 }
 
+                // 如果搜索字符串为空，则返回空游标
                 if (TextUtils.isEmpty(searchString)) {
                     return null;
                 }
 
                 try {
+                    // 将搜索字符串格式化
                     searchString = String.format("%%%s%%", searchString);
+                    // 查询note表，并设置查询条件
                     c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
                             new String[] { searchString });
                 } catch (IllegalStateException ex) {
                     Log.e(TAG, "got exception: " + ex.toString());
                 }
                 break;
+            // 未知uri
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
+        // 如果游标不为空，则设置通知uri
         if (c != null) {
             c.setNotificationUri(getContext().getContentResolver(), uri);
         }
+        // 返回游标
         return c;
     }
 
    @Override
     public Uri insert(Uri uri, ContentValues values) {
+        // 获取可写的数据库
         SQLiteDatabase db = mHelper.getWritableDatabase();
+        // 定义变量
         long dataId = 0, noteId = 0, insertedId = 0;
+        // 根据uri匹配
         switch (mMatcher.match(uri)) {
+            // 匹配到note uri
             case URI_NOTE:
+                // 插入note
                 insertedId = noteId = db.insert(TABLE.NOTE, null, values);
                 break;
+            // 匹配到data uri
             case URI_DATA:
+                // 判断note id是否存在
                 if (values.containsKey(DataColumns.NOTE_ID)) {
                     noteId = values.getAsLong(DataColumns.NOTE_ID);
                 } else {
                     Log.d(TAG, "Wrong data format without note id:" + values.toString());
                 }
+                // 插入data
                 insertedId = dataId = db.insert(TABLE.DATA, null, values);
                 break;
+            // 匹配到其他uri
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
         // Notify the note uri
+        // 通知note uri
         if (noteId > 0) {
             getContext().getContentResolver().notifyChange(
                     ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
         }
 
         // Notify the data uri
+        // 通知data uri
         if (dataId > 0) {
             getContext().getContentResolver().notifyChange(
                     ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
         }
 
+        // 返回插入的id
         return ContentUris.withAppendedId(uri, insertedId);
     }
-
     @Override
     public int delete(Uri uri, String selection, String[] selectionArgs) {
         int count = 0;
@@ -235,21 +278,27 @@ public class NotesProvider extends ContentProvider {
         boolean updateData = false;
         switch (mMatcher.match(uri)) {
             case URI_NOTE:
+                // 增加版本号
                 increaseNoteVersion(-1, selection, selectionArgs);
                 count = db.update(TABLE.NOTE, values, selection, selectionArgs);
                 break;
             case URI_NOTE_ITEM:
+                // 获取id
                 id = uri.getPathSegments().get(1);
+                // 增加版本号
                 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:
+                // 获取id
                 id = uri.getPathSegments().get(1);
+                // 更新数据
                 count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
                         + parseSelection(selection), selectionArgs);
                 updateData = true;
@@ -260,18 +309,22 @@ public class NotesProvider extends ContentProvider {
 
         if (count > 0) {
             if (updateData) {
+                // 通知更新数据
                 getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
             }
+            // 通知更新笔记
             getContext().getContentResolver().notifyChange(uri, null);
         }
         return count;
     }
 
    private String parseSelection(String selection) {
+        // 解析选择语句，返回一个字符串
         return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
     }
 
     private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
+        // 增加笔记的版本
         StringBuilder sql = new StringBuilder(120);
         sql.append("UPDATE ");
         sql.append(TABLE.NOTE);
@@ -299,7 +352,7 @@ public class NotesProvider extends ContentProvider {
     @Override
     public String getType(Uri uri) {
         // TODO Auto-generated method stub
+        // 获取URI的类型
         return null;
     }
-
 }