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NotesProvider.java

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+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.data;
+
+import android.app.SearchManager;
+import android.content.ContentProvider;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.content.Intent;
+import android.content.UriMatcher;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.net.Uri;
+import android.text.TextUtils;
+import android.util.Log;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes.DataColumns;
+import net.micode.notes.data.Notes.NoteColumns;
+import net.micode.notes.data.NotesDatabaseHelper.TABLE;
+
+// 主要的 NotesProvider 类，继承自 ContentProvider
+public class NotesProvider extends ContentProvider {
+    private static final UriMatcher mMatcher; // URI匹配器
+
+    private NotesDatabaseHelper mHelper; // 数据库帮助类
+
+    private static final String TAG = "NotesProvider"; // 日志标签
+
+    // 定义URI匹配码
+    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;
+
+    // 初始化URI匹配器
+    static {
+        mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
+        mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
+        mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
+        mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
+        mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);
+        mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
+    }
+
+    // 定义搜索时使用的投影
+    /**
+     * 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.
+     */
+    private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
+        + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
+        + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + ","
+        + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_2 + ","
+        + R.drawable.search_result + " AS " + SearchManager.SUGGEST_COLUMN_ICON_1 + ","
+        + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
+        + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
+
+    // 定义搜索查询
+    private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
+        + " FROM " + TABLE.NOTE
+        + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
+        + " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER
+        + " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;
+
+    @Override
+    public boolean onCreate() {
+        mHelper = NotesDatabaseHelper.getInstance(getContext()); // 获取数据库帮助类的实例
+        return true;
+    }
+
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
+            String sortOrder) {
+        Cursor c = null;
+        SQLiteDatabase db = mHelper.getReadableDatabase(); // 获取可读数据库
+        String id = null;
+        switch (mMatcher.match(uri)) { // 匹配URI
+            case URI_NOTE:
+                c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
+                        sortOrder);
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1); // 获取路径中的ID
+                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_DATA:
+                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
+                        sortOrder);
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1); // 获取路径中的ID
+                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_SEARCH:
+            case URI_SEARCH_SUGGEST:
+                if (sortOrder != null || projection != null) {
+                    throw new IllegalArgumentException(
+                            "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
+                }
+
+                String searchString = null;
+                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
+                    if (uri.getPathSegments().size() > 1) {
+                        searchString = uri.getPathSegments().get(1);
+                    }
+                } else {
+                    searchString = uri.getQueryParameter("pattern");
+                }
+
+                if (TextUtils.isEmpty(searchString)) {
+                    return null;
+                }
+
+                try {
+                    searchString = String.format("%%%s%%", searchString);
+                    c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
+                            new String[] { searchString });
+                } catch (IllegalStateException ex) {
+                    Log.e(TAG, "got exception: " + ex.toString());
+                }
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        if (c != null) {
+            c.setNotificationUri(getContext().getContentResolver(), uri); // 设置通知URI
+        }
+        return c;
+    }
+
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {
+        SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写数据库
+        long dataId = 0, noteId = 0, insertedId = 0;
+        switch (mMatcher.match(uri)) { // 匹配URI
+            case URI_NOTE:
+                insertedId = noteId = db.insert(TABLE.NOTE, null, values); // 插入笔记
+                break;
+            case URI_DATA:
+                if (values.containsKey(DataColumns.NOTE_ID)) {
+                    noteId = values.getAsLong(DataColumns.NOTE_ID); // 获取笔记ID
+                } else {
+                    Log.d(TAG, "Wrong data format without note id:" + values.toString());
+                }
+                insertedId = dataId = db.insert(TABLE.DATA, null, values); // 插入数据
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        // Notify the note uri
+        if (noteId > 0) {
+            getContext().getContentResolver().notifyChange(
+                    ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
+        }
+
+        // Notify the data uri
+        if (dataId > 0) {
+            getContext().getContentResolver().notifyChange(
+                    ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
+        }
+
+        return ContentUris.withAppendedId(uri, insertedId); // 返回插入的URI
+    }
+
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {
+        int count = 0;
+        String id = null;
+        SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写数据库
+        boolean deleteData = false;
+        switch (mMatcher.match(uri)) { // 匹配URI
+            case URI_NOTE:
+                selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 "; // 确保ID大于0
+                count = db.delete(TABLE.NOTE, selection, selectionArgs); // 删除笔记
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1); // 获取路径中的ID
+                /**
+                 * ID that smaller than 0 is system folder which is not allowed to
+                 * trash
+                 */
+                long noteId = Long.valueOf(id);
+                if (noteId <= 0) {
+                    break;
+                }
+                count = db.delete(TABLE.NOTE,
+                        NoteColumns.ID + "=" +id + parseSelection(selection), selectionArgs); // 删除笔记项
+					break;
+			case URI_DATA:
+				count = db.delete(TABLE.DATA, selection, selectionArgs); // 删除数据
+				deleteData = true;
+					break;
+			case URI_DATA_ITEM:
+				id = uri.getPathSegments().get(1); // 获取路径中的ID
+				count = db.delete(TABLE.DATA,
+				DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs); // 删除数据项
+				deleteData = true;
+				break;
+			default:
+				throw new IllegalArgumentException("Unknown URI " + uri);
+		}
+	if (count > 0) {
+		if (deleteData) {
+			getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); // 通知删除数据
+		}
+		getContext().getContentResolver().notifyChange(uri, null); // 通知删除
+	}		
+	return count;
+}
+@Override
+public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
+    int count = 0;
+    String id = null;
+    SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写数据库
+    boolean updateData = false;
+    switch (mMatcher.match(uri)) { // 匹配URI
+        case URI_NOTE:
+            increaseNoteVersion(-1, selection, selectionArgs); // 增加笔记版本
+            count = db.update(TABLE.NOTE, values, selection, selectionArgs); // 更新笔记
+            break;
+        case URI_NOTE_ITEM:
+            id = uri.getPathSegments().get(1); // 获取路径中的ID
+            increaseNoteVersion(Long.valueOf(id), selection, selectionArgs); // 增加笔记版本
+            count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+                    + parseSelection(selection), selectionArgs); // 更新笔记项
+            break;
+        case URI_DATA:
+            count = db.update(TABLE.DATA, values, selection, selectionArgs); // 更新数据
+            updateData = true;
+            break;
+        case URI_DATA_ITEM:
+            id = uri.getPathSegments().get(1); // 获取路径中的ID
+            count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
+                    + parseSelection(selection), selectionArgs); // 更新数据项
+            updateData = true;
+            break;
+        default:
+            throw new IllegalArgumentException("Unknown URI " + uri);
+    }
+
+    if (count > 0) {
+        if (updateData) {
+            getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); // 通知更新数据
+        }
+        getContext().getContentResolver().notifyChange(uri, null); // 通知更新
+    }
+    return count;
+}
+
+private String parseSelection(String selection) {
+    return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""); // 解析选择条件
+}
+
+private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
+    StringBuilder sql = new StringBuilder(120);
+    sql.append("UPDATE ");
+    sql.append(TABLE.NOTE);
+    sql.append(" SET ");
+    sql.append(NoteColumns.VERSION);
+    sql.append("=" + NoteColumns.VERSION + "+1 ");
+
+    if (id > 0 || !TextUtils.isEmpty(selection)) {
+        sql.append(" WHERE ");
+    }
+    if (id > 0) {
+        sql.append(NoteColumns.ID + "=" + String.valueOf(id));
+    }
+    if (!TextUtils.isEmpty(selection)) {
+        String selectString = id > 0 ? parseSelection(selection) : selection;
+        for (String args : selectionArgs) {
+            selectString = selectString.replaceFirst("\\?", args);
+        }
+        sql.append(selectString);
+    }
+
+    mHelper.getWritableDatabase().execSQL(sql.toString()); // 执行更新SQL
+}
+
+@Override
+public String getType(Uri uri) {
+    // TODO Auto-generated method stub
+    return null;
+}