diff --git a/NotesProvider.java b/NotesProvider.java new file mode 100644 index 0000000..25bf43a --- /dev/null +++ b/NotesProvider.java @@ -0,0 +1,336 @@ +/* + * 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; + +/** + * 为存储和获取数据提供接口，可以在不同的应用程序之间共享数据 + * ContentProvider提供的方法 + * query：查询 + * insert：插入 + * update：更新 + * delete：删除 + * getType：得到数据类型 + */ +public class NotesProvider extends ContentProvider { + //UriMatcher用于匹配Uri + private static final UriMatcher mMatcher; + + private NotesDatabaseHelper mHelper; + + private static final String TAG = "NotesProvider"; + + 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; + + static { + //创建UriMatcher时，调用UriMatcher(UriMatcher.NO_MATCH)表示不匹配任何路径的返回码 + mMatcher = new UriMatcher(UriMatcher.NO_MATCH); + //把需要匹配Uri路径全部给注册上 + 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); + } + + /** + * 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. + */ + //声明NOTES_SEARCH_PROJECTION + 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; +//声明NOTES_SNIPPET_SEARCH_QUERY + 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 + //Context只有在onCreate()中才被初始化 + //对mHelper进行实例化 + public boolean onCreate() { + mHelper = NotesDatabaseHelper.getInstance(getContext()); + return true; + } + + @Override + //查询uri在数据库中对应的位置 + public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, + String sortOrder) { + Cursor c = null; + //获取可读数据库 + SQLiteDatabase db = mHelper.getReadableDatabase(); + String id = null; + //匹配查找uri + switch (mMatcher.match(uri)) { + //对于不同的匹配值，在数据库中查找相应的条目 + case URI_NOTE: + c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null, + sortOrder); + break; + case URI_NOTE_ITEM: + id = uri.getPathSegments().get(1); + 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); + 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) { + //不合法的参数异常 + 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) { + //getPathSegments()方法得到一个String的List， + //在uri.getPathSegments().get(1)为第2个元素 + 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: + //抛出异常 + throw new IllegalArgumentException("Unknown URI " + uri); + } + if (c != null) { + c.setNotificationUri(getContext().getContentResolver(), uri); + } + return c; + } + + @Override + //插入一个uri + public Uri insert(Uri uri, ContentValues values) { + //获得可写的数据库 + SQLiteDatabase db = mHelper.getWritableDatabase(); + long dataId = 0, noteId = 0, insertedId = 0; + switch (mMatcher.match(uri)) { + //新增一个条目 + case URI_NOTE: + insertedId = noteId = db.insert(TABLE.NOTE, null, values); + break; + //如果存在，查找NOTE_ID + case URI_DATA: + if (values.containsKey(DataColumns.NOTE_ID)) { + noteId = values.getAsLong(DataColumns.NOTE_ID); + } else { + Log.d(TAG, "Wrong data format without note id:" + values.toString()); + } + insertedId = dataId = db.insert(TABLE.DATA, null, values); + break; + default: + throw new IllegalArgumentException("Unknown URI " + uri); + } + // Notify the note uri + //notifyChange获得一个getContentResolver对象并且更新里面的内容 + 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); + } +////返回插入的uri的路径 + return ContentUris.withAppendedId(uri, insertedId); + } + + @Override + //删除一个uri + public int delete(Uri uri, String selection, String[] selectionArgs) { + //uri代表要操作的数据，Android上可用的每种资源，包括图像、视频片段、音频资源等都可以用uri来表示 + int count = 0; + String id = null; + //获得可写的数据库 + SQLiteDatabase db = mHelper.getWritableDatabase(); + boolean deleteData = false; + switch (mMatcher.match(uri)) { + case URI_NOTE: + selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 "; + count = db.delete(TABLE.NOTE, selection, selectionArgs); + break; + case URI_NOTE_ITEM: + id = uri.getPathSegments().get(1); + /** + * 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); + break; + case URI_DATA: + count = db.delete(TABLE.DATA, selection, selectionArgs); + deleteData = true; + break; + case URI_DATA_ITEM: + id = uri.getPathSegments().get(1); + count = db.delete(TABLE.DATA, + DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs); + deleteData = true; + break; + default: + throw new IllegalArgumentException("Unknown URI " + uri); + } + if (count > 0) { + if (deleteData) { + getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); + } + getContext().getContentResolver().notifyChange(uri, null); + } + return count; + } + + @Override + //更新一个uri + public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { + int count = 0; + String id = null; + SQLiteDatabase db = mHelper.getWritableDatabase(); + boolean updateData = false; + switch (mMatcher.match(uri)) { + case URI_NOTE: + increaseNoteVersion(-1, selection, selectionArgs); + count = db.update(TABLE.NOTE, values, selection, selectionArgs); + break; + case URI_NOTE_ITEM: + 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: + count = db.update(TABLE.DATA, values, selection, selectionArgs); + updateData = true; + break; + case URI_DATA_ITEM: + id = uri.getPathSegments().get(1); + count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id + + parseSelection(selection), selectionArgs); + updateData = true; + break; + default: + throw new IllegalArgumentException("Unknown URI " + uri); + } + + if (count > 0) { + if (updateData) { + getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); + } + getContext().getContentResolver().notifyChange(uri, null); + } + return count; + } +//将字符串解析成规定格式 + private String parseSelection(String selection) { + return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""); + } +//增加一个NoteVersion + 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); + } +//execSQL()方法可以执行insert、delete、update和CREATE TABLE之类有更改行为的SQL语句 + mHelper.getWritableDatabase().execSQL(sql.toString()); + } + + @Override + public String getType(Uri uri) { + // TODO Auto-generated method stub + return null; + } + +}