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 17 package com.android.demo.notepad2; 18 19 import android.content.ContentValues; 20 import android.content.Context; 21 import android.database.Cursor; 22 import android.database.SQLException; 23 import android.database.sqlite.SQLiteDatabase; 24 import android.database.sqlite.SQLiteOpenHelper; 25 import 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 */ 37 public 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
