/* * 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; } }