1/*
2 * Copyright (C) 2008 Google Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
5 * use this file except in compliance with the License. You may obtain a copy of
6 * the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations under
14 * the License.
15 */
16
17package com.android.demo.notepad2;
18
19import android.content.ContentValues;
20import android.content.Context;
21import android.database.Cursor;
22import android.database.SQLException;
23import android.database.sqlite.SQLiteDatabase;
24import android.database.sqlite.SQLiteOpenHelper;
25import android.util.Log;
26
27/**
28 * Simple notes database access helper class. Defines the basic CRUD operations
29 * for the notepad example, and gives the ability to list all notes as well as
30 * retrieve or modify a specific note.
31 *
32 * This has been improved from the first version of this tutorial through the
33 * addition of better error handling and also using returning a Cursor instead
34 * of using a collection of inner classes (which is less scalable and not
35 * recommended).
36 */
37public class NotesDbAdapter {
38
39    public static final String KEY_TITLE = "title";
40    public static final String KEY_BODY = "body";
41    public static final String KEY_ROWID = "_id";
42
43    private static final String TAG = "NotesDbAdapter";
44    private DatabaseHelper mDbHelper;
45    private SQLiteDatabase mDb;
46
47    /**
48     * Database creation sql statement
49     */
50    private static final String DATABASE_CREATE =
51        "create table notes (_id integer primary key autoincrement, "
52        + "title text not null, body text not null);";
53
54    private static final String DATABASE_NAME = "data";
55    private static final String DATABASE_TABLE = "notes";
56    private static final int DATABASE_VERSION = 2;
57
58    private final Context mCtx;
59
60    private static class DatabaseHelper extends SQLiteOpenHelper {
61
62        DatabaseHelper(Context context) {
63            super(context, DATABASE_NAME, null, DATABASE_VERSION);
64        }
65
66        @Override
67        public void onCreate(SQLiteDatabase db) {
68
69            db.execSQL(DATABASE_CREATE);
70        }
71
72        @Override
73        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
74            Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
75                    + newVersion + ", which will destroy all old data");
76            db.execSQL("DROP TABLE IF EXISTS notes");
77            onCreate(db);
78        }
79    }
80
81    /**
82     * Constructor - takes the context to allow the database to be
83     * opened/created
84     *
85     * @param ctx the Context within which to work
86     */
87    public NotesDbAdapter(Context ctx) {
88        this.mCtx = ctx;
89    }
90
91    /**
92     * Open the notes database. If it cannot be opened, try to create a new
93     * instance of the database. If it cannot be created, throw an exception to
94     * signal the failure
95     *
96     * @return this (self reference, allowing this to be chained in an
97     *         initialization call)
98     * @throws SQLException if the database could be neither opened or created
99     */
100    public NotesDbAdapter open() throws SQLException {
101        mDbHelper = new DatabaseHelper(mCtx);
102        mDb = mDbHelper.getWritableDatabase();
103        return this;
104    }
105
106    public void close() {
107        mDbHelper.close();
108    }
109
110
111    /**
112     * Create a new note using the title and body provided. If the note is
113     * successfully created return the new rowId for that note, otherwise return
114     * a -1 to indicate failure.
115     *
116     * @param title the title of the note
117     * @param body the body of the note
118     * @return rowId or -1 if failed
119     */
120    public long createNote(String title, String body) {
121        ContentValues initialValues = new ContentValues();
122        initialValues.put(KEY_TITLE, title);
123        initialValues.put(KEY_BODY, body);
124
125        return mDb.insert(DATABASE_TABLE, null, initialValues);
126    }
127
128    /**
129     * Delete the note with the given rowId
130     *
131     * @param rowId id of note to delete
132     * @return true if deleted, false otherwise
133     */
134    public boolean deleteNote(long rowId) {
135
136        return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
137    }
138
139    /**
140     * Return a Cursor over the list of all notes in the database
141     *
142     * @return Cursor over all notes
143     */
144    public Cursor fetchAllNotes() {
145
146        return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE,
147                KEY_BODY}, null, null, null, null, null);
148    }
149
150    /**
151     * Return a Cursor positioned at the note that matches the given rowId
152     *
153     * @param rowId id of note to retrieve
154     * @return Cursor positioned to matching note, if found
155     * @throws SQLException if note could not be found/retrieved
156     */
157    public Cursor fetchNote(long rowId) throws SQLException {
158
159        Cursor mCursor =
160
161            mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
162                    KEY_TITLE, KEY_BODY}, KEY_ROWID + "=" + rowId, null,
163                    null, null, null, null);
164        if (mCursor != null) {
165            mCursor.moveToFirst();
166        }
167        return mCursor;
168
169    }
170
171    /**
172     * Update the note using the details provided. The note to be updated is
173     * specified using the rowId, and it is altered to use the title and body
174     * values passed in
175     *
176     * @param rowId id of note to update
177     * @param title value to set note title to
178     * @param body value to set note body to
179     * @return true if the note was successfully updated, false otherwise
180     */
181    public boolean updateNote(long rowId, String title, String body) {
182        ContentValues args = new ContentValues();
183        args.put(KEY_TITLE, title);
184        args.put(KEY_BODY, body);
185
186        return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
187    }
188}
189