androidでSQLiteデータベースを作成
3つのテーブルを含むアプリでSQLiteデータベースを作成したいので、テーブルにデータを追加し、後で使用します。
しかし、データベースを保持したいので、アプリを初めてインストールするときにデータベースが存在するかどうかをチェックし、存在する場合は更新し、存在しない場合は更新してから新しいデータベースを作成します。
さらに、アプリを容易にするためにDBクラスを作成しているため、データベース作成用のアクティビティを作成しません。
可能なアドバイスがあれば、私と共有してください
より良い例は[こちら]
try {
myDB = this.openOrCreateDatabase("DatabaseName", MODE_PRIVATE, null);
/* Create a Table in the Database. */
myDB.execSQL("CREATE TABLE IF NOT EXISTS "
+ TableName
+ " (Field1 VARCHAR, Field2 INT(3));");
/* Insert data to a Table*/
myDB.execSQL("INSERT INTO "
+ TableName
+ " (Field1, Field2)"
+ " VALUES ('Saranga', 22);");
/*retrieve data from database */
Cursor c = myDB.rawQuery("SELECT * FROM " + TableName , null);
int Column1 = c.getColumnIndex("Field1");
int Column2 = c.getColumnIndex("Field2");
// Check if our result was valid.
c.moveToFirst();
if (c != null) {
// Loop through all Results
do {
String Name = c.getString(Column1);
int Age = c.getInt(Column2);
Data =Data +Name+"/"+Age+"\n";
}while(c.moveToNext());
}
アンインストール間でデータベースを保持する場合は、SDカードに保存する必要があります。これは、アプリが削除された時点で削除されない唯一の場所です。ただし、その代わりに、ユーザーが毎回削除できます。
DBをSDカードに配置すると、 SQLiteOpenHelper を使用できなくなりますが、このクラスのソースとアーキテクチャを使用して、作成、更新、およびデータベースのオープン。
public class MyDatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "MyDb.db";
private static final int DATABASE_VERSION = 1;
// Database creation sql statement
private static final String DATABASE_CREATE_FRIDGE_ITEM = "create table FridgeItem(id integer primary key autoincrement,f_id text not null,food_item text not null,quantity text not null,measurement text not null,expiration_date text not null,current_date text not null,flag text not null,location text not null);";
public MyDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Method is called during creation of the database
@Override
public void onCreate(SQLiteDatabase database) {
database.execSQL(DATABASE_CREATE_FRIDGE_ITEM);
}
// Method is called during an upgrade of the database,
@Override
public void onUpgrade(SQLiteDatabase database,int oldVersion,int newVersion){
Log.w(MyDatabaseHelper.class.getName(),"Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
database.execSQL("DROP TABLE IF EXISTS FridgeItem");
onCreate(database);
}
}
public class CommentsDataSource {
private MyDatabaseHelper dbHelper;
private SQLiteDatabase database;
public String stringArray[];
public final static String FOOD_TABLE = "FridgeItem"; // name of table
public final static String FOOD_ITEMS_DETAILS = "FoodDetails"; // name of table
public final static String P_ID = "id"; // pid
public final static String FOOD_ID = "f_id"; // id value for food item
public final static String FOOD_NAME = "food_item"; // name of food
public final static String FOOD_QUANTITY = "quantity"; // quantity of food item
public final static String FOOD_MEASUREMENT = "measurement"; // measurement of food item
public final static String FOOD_EXPIRATION = "expiration_date"; // expiration date of food item
public final static String FOOD_CURRENTDATE = "current_date"; // date of food item added
public final static String FLAG = "flag";
public final static String LOCATION = "location";
/**
*
* @param context
*/
public CommentsDataSource(Context context) {
dbHelper = new MyDatabaseHelper(context);
database = dbHelper.getWritableDatabase();
}
public long insertFoodItem(String id, String name,String quantity, String measurement, String currrentDate,String expiration,String flag,String location) {
ContentValues values = new ContentValues();
values.put(FOOD_ID, id);
values.put(FOOD_NAME, name);
values.put(FOOD_QUANTITY, quantity);
values.put(FOOD_MEASUREMENT, measurement);
values.put(FOOD_CURRENTDATE, currrentDate);
values.put(FOOD_EXPIRATION, expiration);
values.put(FLAG, flag);
values.put(LOCATION, location);
return database.insert(FOOD_TABLE, null, values);
}
public long insertFoodItemsDetails(String id, String name,String quantity, String measurement, String currrentDate,String expiration) {
ContentValues values = new ContentValues();
values.put(FOOD_ID, id);
values.put(FOOD_NAME, name);
values.put(FOOD_QUANTITY, quantity);
values.put(FOOD_MEASUREMENT, measurement);
values.put(FOOD_CURRENTDATE, currrentDate);
values.put(FOOD_EXPIRATION, expiration);
return database.insert(FOOD_ITEMS_DETAILS, null, values);
}
public Cursor selectRecords(String id) {
String[] cols = new String[] { FOOD_ID, FOOD_NAME, FOOD_QUANTITY, FOOD_MEASUREMENT, FOOD_EXPIRATION,FLAG,LOCATION,P_ID};
Cursor mCursor = database.query(true, FOOD_TABLE, cols, P_ID+"=?", new String[]{id}, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor; // iterate to get each value.
}
public Cursor selectAllName() {
String[] cols = new String[] { FOOD_NAME};
Cursor mCursor = database.query(true, FOOD_TABLE, cols, null, null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor; // iterate to get each value.
}
public Cursor selectAllRecords(String loc) {
String[] cols = new String[] { FOOD_ID, FOOD_NAME, FOOD_QUANTITY, FOOD_MEASUREMENT, FOOD_EXPIRATION,FLAG,LOCATION,P_ID};
Cursor mCursor = database.query(true, FOOD_TABLE, cols, LOCATION+"=?", new String[]{loc}, null, null, null, null);
int size=mCursor.getCount();
stringArray = new String[size];
int i=0;
if (mCursor != null) {
mCursor.moveToFirst();
FoodInfo.arrayList.clear();
while (!mCursor.isAfterLast()) {
String name=mCursor.getString(1);
stringArray[i]=name;
String quant=mCursor.getString(2);
String measure=mCursor.getString(3);
String expir=mCursor.getString(4);
String id=mCursor.getString(7);
FoodInfo fooditem=new FoodInfo();
fooditem.setName(name);
fooditem.setQuantity(quant);
fooditem.setMesure(measure);
fooditem.setExpirationDate(expir);
fooditem.setid(id);
FoodInfo.arrayList.add(fooditem);
mCursor.moveToNext();
i++;
}
}
return mCursor; // iterate to get each value.
}
public Cursor selectExpDate() {
String[] cols = new String[] {FOOD_NAME, FOOD_QUANTITY, FOOD_MEASUREMENT, FOOD_EXPIRATION};
Cursor mCursor = database.query(true, FOOD_TABLE, cols, null, null, null, null, FOOD_EXPIRATION, null);
int size=mCursor.getCount();
stringArray = new String[size];
if (mCursor != null) {
mCursor.moveToFirst();
FoodInfo.arrayList.clear();
while (!mCursor.isAfterLast()) {
String name=mCursor.getString(0);
String quant=mCursor.getString(1);
String measure=mCursor.getString(2);
String expir=mCursor.getString(3);
FoodInfo fooditem=new FoodInfo();
fooditem.setName(name);
fooditem.setQuantity(quant);
fooditem.setMesure(measure);
fooditem.setExpirationDate(expir);
FoodInfo.arrayList.add(fooditem);
mCursor.moveToNext();
}
}
return mCursor; // iterate to get each value.
}
public int UpdateFoodItem(String id, String quantity, String expiration){
ContentValues values=new ContentValues();
values.put(FOOD_QUANTITY, quantity);
values.put(FOOD_EXPIRATION, expiration);
return database.update(FOOD_TABLE, values, P_ID+"=?", new String[]{id});
}
public void deleteComment(String id) {
System.out.println("Comment deleted with id: " + id);
database.delete(FOOD_TABLE, P_ID+"=?", new String[]{id});
}
}
これは直接使用するための完全なソースコードです。
public class CardDBDAO {
protected SQLiteDatabase database;
private DataBaseHelper dbHelper;
private Context mContext;
public CardDBDAO(Context context) {
this.mContext = context;
dbHelper = DataBaseHelper.getHelper(mContext);
open();
}
public void open() throws SQLException {
if(dbHelper == null)
dbHelper = DataBaseHelper.getHelper(mContext);
database = dbHelper.getWritableDatabase();
}
}
public class DataBaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "mydbnamedb";
private static final int DATABASE_VERSION = 1;
public static final String CARDS_TABLE = "tbl_cards";
public static final String POICATEGORIES_TABLE = "tbl_poicategories";
public static final String POILANGS_TABLE = "tbl_poilangs";
public static final String ID_COLUMN = "id";
public static final String POI_ID = "poi_id";
public static final String POICATEGORIES_COLUMN = "poi_categories";
public static final String POILANGS_COLUMN = "poi_langs";
public static final String CARDS = "cards";
public static final String CARD_ID = "card_id";
public static final String CARDS_PCAT_ID = "pcat_id";
public static final String CREATE_PLANG_TABLE = "CREATE TABLE "
+ POILANGS_TABLE + "(" + ID_COLUMN + " INTEGER PRIMARY KEY,"
+ POILANGS_COLUMN + " TEXT, " + POI_ID + " TEXT)";
public static final String CREATE_PCAT_TABLE = "CREATE TABLE "
+ POICATEGORIES_TABLE + "(" + ID_COLUMN + " INTEGER PRIMARY KEY,"
+ POICATEGORIES_COLUMN + " TEXT, " + POI_ID + " TEXT)";
public static final String CREATE_CARDS_TABLE = "CREATE TABLE "
+ CARDS_TABLE + "(" + ID_COLUMN + " INTEGER PRIMARY KEY," + CARD_ID
+ " TEXT, " + CARDS_PCAT_ID + " TEXT, " + CARDS + " TEXT)";
private static DataBaseHelper instance;
public static synchronized DataBaseHelper getHelper(Context context) {
if (instance == null)
instance = new DataBaseHelper(context);
return instance;
}
private DataBaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onOpen(SQLiteDatabase db) {
super.onOpen(db);
if (!db.isReadOnly()) {
// Enable foreign key constraints
// db.execSQL("PRAGMA foreign_keys=ON;");
}
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_PCAT_TABLE);
db.execSQL(CREATE_PLANG_TABLE);
db.execSQL(CREATE_CARDS_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
public class PoiLangDAO extends CardDBDAO {
private static final String WHERE_ID_EQUALS = DataBaseHelper.ID_COLUMN
+ " =?";
public PoiLangDAO(Context context) {
super(context);
}
public long save(PLang plang_data) {
ContentValues values = new ContentValues();
values.put(DataBaseHelper.POI_ID, plang_data.getPoi_id());
values.put(DataBaseHelper.POILANGS_COLUMN, plang_data.getLangarr());
return database
.insert(DataBaseHelper.POILANGS_TABLE, null, values);
}
public long update(PLang plang_data) {
ContentValues values = new ContentValues();
values.put(DataBaseHelper.POI_ID, plang_data.getPoi_id());
values.put(DataBaseHelper.POILANGS_COLUMN, plang_data.getLangarr());
long result = database.update(DataBaseHelper.POILANGS_TABLE,
values, WHERE_ID_EQUALS,
new String[] { String.valueOf(plang_data.getId()) });
Log.d("Update Result:", "=" + result);
return result;
}
public int deleteDept(PLang plang_data) {
return database.delete(DataBaseHelper.POILANGS_TABLE,
WHERE_ID_EQUALS, new String[] { plang_data.getId() + "" });
}
public List<PLang> getPLangs1() {
List<PLang> plang_list = new ArrayList<PLang>();
Cursor cursor = database.query(DataBaseHelper.POILANGS_TABLE,
new String[] { DataBaseHelper.ID_COLUMN, DataBaseHelper.POI_ID,
DataBaseHelper.POILANGS_COLUMN }, null, null, null,
null, null);
while (cursor.moveToNext()) {
PLang plang_bin = new PLang();
plang_bin.setId(cursor.getInt(0));
plang_bin.setPoi_id(cursor.getString(1));
plang_bin.setLangarr(cursor.getString(2));
plang_list.add(plang_bin);
}
return plang_list;
}
public List<PLang> getPLangs(String pid) {
List<PLang> plang_list = new ArrayList<PLang>();
String selection = DataBaseHelper.POI_ID + "=?";
String[] selectionArgs = { pid };
Cursor cursor = database.query(DataBaseHelper.POILANGS_TABLE,
new String[] { DataBaseHelper.ID_COLUMN, DataBaseHelper.POI_ID,
DataBaseHelper.POILANGS_COLUMN }, selection,
selectionArgs, null, null, null);
while (cursor.moveToNext()) {
PLang plang_bin = new PLang();
plang_bin.setId(cursor.getInt(0));
plang_bin.setPoi_id(cursor.getString(1));
plang_bin.setLangarr(cursor.getString(2));
plang_list.add(plang_bin);
}
return plang_list;
}
public void loadPLangs(String poi_id, String langarrs) {
PLang plangbin = new PLang(poi_id, langarrs);
List<PLang> plang_arr = new ArrayList<PLang>();
plang_arr.add(plangbin);
for (PLang dept : plang_arr) {
ContentValues values = new ContentValues();
values.put(DataBaseHelper.POI_ID, dept.getPoi_id());
values.put(DataBaseHelper.POILANGS_COLUMN, dept.getLangarr());
database.insert(DataBaseHelper.POILANGS_TABLE, null, values);
}
}
}
public class PLang {
public PLang() {
super();
}
public PLang(String poi_id, String langarrs) {
// TODO Auto-generated constructor stub
this.poi_id = poi_id;
this.langarr = langarrs;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getPoi_id() {
return poi_id;
}
public void setPoi_id(String poi_id) {
this.poi_id = poi_id;
}
public String getLangarr() {
return langarr;
}
public void setLangarr(String langarr) {
this.langarr = langarr;
}
private int id;
private String poi_id;
private String langarr;
}
ここにコードがあります
DatabaseMyHandler.class
public class DatabaseMyHandler extends SQLiteOpenHelper {
private SQLiteDatabase myDataBase;
private Context context = null;
private static String TABLE_NAME = "customer";
public static final String DATABASE_NAME = "Student.db";
public final static String DATABASE_PATH = "/data/data/com.pkgname/databases/";
public static final int DATABASE_VERSION = 2;
public DatabaseMyHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.context = context;
try {
createDatabase();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
myDataBase = sqLiteDatabase;
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
//Check database already exists or not
private boolean checkDatabaseExists() {
boolean checkDB = false;
try {
String PATH = DATABASE_PATH + DATABASE_NAME;
File dbFile = new File(PATH);
checkDB = dbFile.exists();
} catch (SQLiteException e) {
}
return checkDB;
}
//Create a empty database on the system
public void createDatabase() throws IOException {
boolean dbExist = checkDatabaseExists();
if (dbExist) {
Log.v("DB Exists", "db exists");
}
boolean dbExist1 = checkDatabaseExists();
if (!dbExist1) {
this.getWritableDatabase();
try {
this.close();
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
//Copies your database from your local assets-folder to the just created empty database in the system folder
private void copyDataBase() throws IOException {
String outFileName = DATABASE_PATH + DATABASE_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
InputStream myInput = context.getAssets().open(DATABASE_NAME);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
myInput.close();
myOutput.flush();
myOutput.close();
}
//Open Database
public void openDatabase() throws SQLException {
String PATH = DATABASE_PATH + DATABASE_NAME;
myDataBase = SQLiteDatabase.openDatabase(PATH, null, SQLiteDatabase.OPEN_READWRITE);
}
//for insert data into database
public void insertCustomer(String customer_id, String email_id, String password, String description, int balance_amount) {
try {
openDatabase();
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("customer_id", customer_id);
contentValues.put("email_id", email_id);
contentValues.put("password", password);
contentValues.put("description", description);
contentValues.put("balance_amount", balance_amount);
db.insert(TABLE_NAME, null, contentValues);
} catch (SQLException e) {
e.printStackTrace();
}
}
public ArrayList<ModelCreateCustomer> getLoginIdDetail(String email_id, String password) {
ArrayList<ModelCreateCustomer> result = new ArrayList<ModelCreateCustomer>();
//boolean flag = false;
String selectQuery = "SELECT * FROM " + TABLE_NAME + " WHERE email_id='" + email_id + "' AND password='" + password + "'";
try {
openDatabase();
Cursor cursor = myDataBase.rawQuery(selectQuery, null);
//cursor.moveToFirst();
if (cursor.getCount() > 0) {
if (cursor.moveToFirst()) {
do {
ModelCreateCustomer model = new ModelCreateCustomer();
model.setId(cursor.getInt(cursor.getColumnIndex("id")));
model.setCustomerId(cursor.getString(cursor.getColumnIndex("customer_id")));
model.setCustomerEmailId(cursor.getString(cursor.getColumnIndex("email_id")));
model.setCustomerPassword(cursor.getString(cursor.getColumnIndex("password")));
model.setCustomerDesription(cursor.getString(cursor.getColumnIndex("description")));
model.setCustomerBalanceAmount(cursor.getInt(cursor.getColumnIndex("balance_amount")));
result.add(model);
}
while (cursor.moveToNext());
}
Toast.makeText(context, "Login Successfully", Toast.LENGTH_SHORT).show();
}
// Log.e("Count", "" + cursor.getCount());
cursor.close();
myDataBase.close();
} catch (SQLException e) {
e.printStackTrace();
}
return result;
}
public void updateCustomer(String id, String email_id, String description, int balance_amount) {
try {
openDatabase();
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("email_id", email_id);
contentValues.put("description", description);
contentValues.put("balance_amount", balance_amount);
db.update(TABLE_NAME, contentValues, "id=" + id, null);
} catch (SQLException e) {
e.printStackTrace();
}
}
}
Customer.class
public class Customer extends AppCompatActivity{
private DatabaseMyHandler mydb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_customer);
mydb = new DatabaseMyHandler(CreateCustomerActivity.this);
mydb.insertCustomer("1", "[email protected]", "123", "test", 100);
}
}
ドキュメント またはSDKに同梱されているサンプルコードを参照しないのはなぜですか？サンプルには、リンクしたドキュメントに記載されているヘルパークラスを使用してデータベースを作成、更新、入力、読み取りする方法に関するコードがあります。
Androidベストプラクティスでのsqliteデータベースの使用方法を理解するには、 Android with sqlite database を参照してください。
知っておくべきいくつかのクラスがあり、それらはテーブルやモデルをモデル化するのに役立ちます。つまり、Android.provider.BaseColumns
以下はテーブルの例です
public class ProductTable implements BaseColumns {
public static final String NAME = "name";
public static final String PRICE = "price";
public static final String TABLE_NAME = "products";
public static final String CREATE_QUERY = "create table " + TABLE_NAME + " (" +
_ID + " INTEGER, " +
NAME + " TEXT, " +
PRICE + " INTEGER)";
public static final String DROP_QUERY = "drop table " + TABLE_NAME;
public static final String SElECT_QUERY = "select * from " + TABLE_NAME;
}
DBに今日の生活のTodoリストを挿入し、すべてのTodoリストのリストを取得する簡単なデータベースの例。
public class MyDatabaseHelper extends SQLiteOpenHelper {
// Logcat tag
private static final String LOG = "DatabaseHelper";
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "SQLiteDemoDB";
// Table Names
private static final String TABLE_TODO = "todos";
// column names
private static final String KEY_ID = "id";
private static final String KEY_CREATED_AT = "created_at";
private static final String KEY_TODO = "todoDescr";
// *********************************************************************************************
public MyDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE_TODO);
}
// Upgrading database **************************************************************************
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_TODO);
// Create tables again
onCreate(db);
}
// Creating Table TABLE_TEAM
String CREATE_TABLE_TODO = "CREATE TABLE " + TABLE_TODO + "("
+ KEY_ID + " integer primary key autoincrement, "
+ KEY_TODO + " text, "
+ KEY_CREATED_AT + " text" + ")";
// insert values of todo
public boolean InsertTodoDetails(String todo, String createdAt) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_TODO, todo);
contentValues.put(KEY_CREATED_AT, createdAt);
long rowInserted = db.insert(TABLE_TODO, null, contentValues);
db.close();
return true;
}
// Select values of todo
public Cursor GetAllTodoDetails() {
SQLiteDatabase db = this.getReadableDatabase();
String query = "SELECT * FROM " + TABLE_TODO;
Cursor mcursor = db.rawQuery(query, null);
if (mcursor != null) {
mcursor.moveToFirst();
}
return mcursor;
}
}
私の活動記録を保存して取得する。
public class MyDbActivity extends AppCompatActivity {
@Bind(R.id.edt_todo)
EditText edtTodo;
@Bind(R.id.btn_save)
Button btnSave;
MyDatabaseHelper db;
@Bind(R.id.btn_getTodo)
Button btnGetTodo;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my_db);
ButterKnife.bind(this);
// creating database object
db = new MyDatabaseHelper(this);
}
@OnClick(R.id.btn_save)
public void onViewClicked() {
String datetime = "";
try {
SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
datetime = dateformat.format(new Date());
} catch (Exception e) {
e.printStackTrace();
}
db.InsertTodoDetails(edtTodo.getText().toString().trim(), datetime);
}
@OnClick(R.id.btn_getTodo)
public void onGetTodoClicked() {
String todos = "";
Cursor TodoList = db.GetAllTodoDetails();
if (TodoList.moveToFirst()) {
do {
if (todos.equals("")) {
todos = TodoList.getString(TodoList.getColumnIndex("todoDescr"));
} else {
todos = todos + ", " + TodoList.getString(TodoList.getColumnIndex("todoDescr"));
}
// do what ever you want here
} while (TodoList.moveToNext());
}
TodoList.close();
Toast.makeText(this, "" + todos, Toast.LENGTH_SHORT).show();
}
}