In my application, I use the users password as the encryption key for encryption media. I am encrypting media using PBEWithMD5AndDES and this works fine with a password stored in shared preferences. Now to achieve a level of security I am removing the password from shared preferences and using a singleton that is only kept alive during the app session (as the app logs out automatically requiring entry of the password). Below is my singleton:
public class Credentials {
private static Credentials dataObject = null;
private Credentials() {
// left blank intentionally
}
public static Credentials getInstance() {
if (dataObject == null)
dataObject = new Credentials();
return dataObject;
}
private char[] user_password;
public char[] getUser_password() {
return user_password;
}
public void setUser_password(char[] user_password) {
this.user_password = user_password;
}
}
The password is zeroed out from memory if the app logs out, or is log out by the user or gets destroyed. However at times I am getting a null pointer when trying to retrieve the password.
char[] pswd = Credentials.getInstance().getUser_password();
What could be causing this? is there any other method I can use except a singleton?
Alternatively, you can store the password using built-in Sqlite db, though I'd still recommend you save it encrypted for max protection. You can do this in 4 steps:
2) Create an entity object to store the password:
public class Password {
int password_id; // will be auto-increamted
String password;
public Password(int password_id, String password) {
this.password_id = password_id;
this.password = password;
}
// getter/setters ...
}
2) Create an Sqlite utility object:
public class SQLiteDBAdapter {
protected static final String DATABASE_NAME = "mydb";
protected static final int DATABASE_VERSION = 1;
protected Context context;
protected static DatabaseHelper mDbHelper;
public static final String TABLE_PASSWORD = "tbl_password";
// columns
public static final String PASSWORD_ID = "_id";
public static final String PASSWORD = "password";
// create table string
private static final String CREATE_TABLE_PASSWORD =
"CREATE TABLE if not exists " + TABLE_PASSWORD + " ( " +
PASSWORD_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
PASSWORD + " TEXT NOT NULL);";
public SQLiteDBAdapter(Context context) {
context = context.getApplicationContext();
}
public SQLiteDatabase openDb() {
if (mDbHelper == null) {
mDbHelper = new DatabaseHelper(mContext);
}
return mDbHelper.getWritableDatabase();
}
protected static class DatabaseHelper extends SQLiteOpenHelper {
// -------------------------------------------------------------------------------------------
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// -------------------------------------------------------------------------------------------
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE_PASSWORD);
}
// -------------------------------------------------------------------------------------------
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to " +
newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS routes");
onCreate(db);
}
}
}
3) Extend an Sqlite object to manipulate the table (CRUD operations):
public class PasswordDbAdapter extends SQLiteDBAdapter {
private SQLiteDatabase db;
// these are column corresponding indices
public static final int INDEX_PASSWORD_ID = 0; // an auto-increment
public static final int INDEX_PASSWORD = 1;
public PasswordDbAdapter(Context context) {
super(context);
}
public void addPassword(String password) {
db = openDb();
ContentValues values = new ContentValues();
values.put(PASSWORD, password);
db.insert(TABLE_PASSWORD, null, values);
}
public void updatePassword(String password) {
db = openDb();
ContentValues values = new ContentValues();
values.put(PASSWORD, password);
db.update(TABLE_PASSWORD, values, null);
}
public void deletePassword() {
db = openDb();
db.delete(TABLE_PASSWORD, null, null);
}
public boolean isEmpty() {
db = openDb();
boolean empty = true;
Cursor cur = db.rawQuery("SELECT COUNT(*) FROM " + TABLE_PASSWORD, null);
if (cur != null && cur.moveToFirst()) {
empty = (cur.getInt (0) == 0);
}
cur.close();
return empty;
}
public Password fetchPassword() { // ok because there's only one password record
db = openDb();
Cursor cursor = db.query(TABLE_PASSWORD, new String[]{PASSWORD_ID, PASSWORD},
null, null, null, null, null, null);
if (cursor != null &&
cursor.moveToFirst()) {
return new Password(
cursor.getString(INDEX_PASSWORD_ID),
cursor.getInt(INDEX_PASSWORD));
}
return null;
}
}
4) Finally, save/update/retrieve the password as desired:
public class MainActivity extends AppCompatActivity {
private PasswordDbAdapter passwordDB;
#Override
protected void onCreate(Bundle savedInstanceState) {
...
// initialize the password db
passwordDB = new PasswordDbAdapter(this);
// check if password record exists
if (passwordDB.isEmpty() {
// save a new copy
passwordDB.addPassword("the_password"); // more secure if it is saved encrypted
} else {
// update it
passwordDB.updatePassword("the_password");
}
}
...
public String fetchPassword() {
return passwordDB.fetchPassword(); // or first decrypt it, then return it
}
}
Related
This question already has an answer here:
sqlite get ROWID
(1 answer)
Closed 1 year ago.
I have an android studio app that uses sqlite to save user data such as username, password, etc. In the login page after the user enters his login credentials, the user clicks on a button that calls the following function from a DatabaseHelper java class to check if the info is correct:
public boolean checkLogin(String username, String password){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM user WHERE username=? AND password=? ",
new String[] {username, password});
if (cursor.getCount() > 0){
return true;
}
else {
return false;
}
}
I want to save the row ID that matches this user so I can use it in the future and I was thinking of saving the ID into a variable that I will then send to different activities using an intent. The issue is that I can't figure out how to save the ID from the query.
I'd suggest returning a int rather than boolean the long being the id or -1 if the user/password combination doesn't exist. So :-
public int checkLogin(String username, String password){
int rv = -1;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM user WHERE username=? AND password=? ",
new String[] {username, password});
if (cursor.moveToFirst()) {
rv = cursor.getInt(cursor.getColumnIndex("id"));
}
cursor.close();
return rv;
}
Instead of using something like :-
if (checkLogin("the_user","the_password")) {
logged in code ....
} else {
not logged in code ....
}
You could use something like :-
private int current_userid = -1; // probably declared as a class variable
....
if ((current_userid = db.checkLogin("the_user","the_password")) > 0 ) {
logged in OK code ....
} else {
not logged in code ....
}
I want to save the row ID that matches this user so I can use it in the future and I was thinking of saving the ID into a variable that I will then send to different activities using an intent.
Here's an example that does that and sends the id to another Activity (NextActivity) and then returns (finishes) from that activity after writing the username and password to the log.
First the Database Helper DBHelper :-
class DBHelper extends SQLiteOpenHelper {
SQLiteDatabase db;
public DBHelper(#Nullable Context context) {
super(context, "mydb", null, 1);
db = this.getWritableDatabase();
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE IF NOT EXISTS user (" +
"id INTEGER PRIMARY KEY, " +
"username TEXT UNIQUE, " +
"password TEXT " +
")");
ContentValues cv = new ContentValues();
cv.put("username","fred");
cv.put("password","password_for_fred");
db.insert("user",null,cv);
}
#Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) { }
public int checkLogin(String username, String password){
int rv = -1;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM user WHERE username=? AND password=? ",
new String[] {username, password});
if (cursor.moveToFirst()) {
rv = cursor.getInt(cursor.getColumnIndex("id"));
}
cursor.close();
return rv;
}
public Cursor getUserById(int userId) {
return db.query("user",null,"id=?",new String[]{String.valueOf(userId)},null,null,null);
}
}
Note that this uses a single class variable for the SQLiteDatabase, so only needs the 1 getWriteableDatabase. It also forces the database to open when constructing by including db = this.getWriteableDatabase(); in the constructor.
Note the added method getUserById(ing userId) method which returns a Cursor according to the userId.
Note that a demo user is added to the table when it is created.
MainActivity (a little overly complex as it demonstrates both a failed login attempt (1st) as well as a successful login attempt (as part of handling the failed attempt)) :-
public class MainActivity extends AppCompatActivity {
public static final String INTENT_EXTRA_CURRENT_USERID = "current_userid";
DBHelper db;
private int current_userid = -1;
private Intent intent;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
db = new DBHelper(this);
Log.d("LOGIN1","Attempting to Login"); // Will purposefully fail login
if ((current_userid = db.checkLogin("the_user","the_password")) > 0 ) {
Log.d("LOGIN2","Successfully Logged in to user with ID = " + String.valueOf(current_userid));
gotoNextActivity();
} else {
Toast.makeText(this,"Invalid Login, please try again",Toast.LENGTH_SHORT).show();
Log.d("LOGIN1","First attempt to login failed");
// Make 2nd attempt (will work as username and password are correct)
Log.d("LOGIN2","Attemtping to Login (2nd) ");
if((current_userid = db.checkLogin("fred","password_for_fred")) > 0 ) {
Log.d("LOGIN2","Successfully Logged in to user with ID = " + String.valueOf(current_userid));
gotoNextActivity();
}
}
}
private void gotoNextActivity() {
intent = new Intent(this,NextActivity.class);
intent.putExtra(INTENT_EXTRA_CURRENT_USERID,current_userid);
startActivity(intent);
}
}
Finally NextActivity :-
public class NextActivity extends AppCompatActivity {
private int current_userid;
private String current_username, current_password;
private DBHelper db;
Cursor csr;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_next);
db = new DBHelper(this);
current_userid = this.getIntent().getIntExtra(MainActivity.INTENT_EXTRA_CURRENT_USERID,-1);
csr = db.getUserById(current_userid);
if (csr.moveToFirst()) {
current_username = csr.getString(csr.getColumnIndex("username"));
current_password = csr.getString(csr.getColumnIndex("password"));
}
if (current_userid > 0) {
Log.d("NEXTACTIVTY","Valid user ID - Username = " + current_username + " password is " + current_password);
} else {
Log.d("NEXTACTIVITY","No Valid userid?");
}
// Finish the Activity and hence return to MainActivity
// Hence it is unlikely that the NextActivity will even be noticed.
finish();
}
#Override
protected void onDestroy() {
super.onDestroy();
if (!csr.isClosed()) {
csr.close();
Log.d("NEXTACTIVITY","Closing Cursor in onDestroy method");
}
}
}
Result
When run the log includes :-
2021-07-17 12:19:37.201 D/LOGIN1: Attempting to Login
2021-07-17 12:19:37.211 D/LOGIN1: First attempt to login failed
2021-07-17 12:19:37.211 D/LOGIN2: Attemtping to Login (2nd)
2021-07-17 12:19:37.212 D/LOGIN2: Successfully Logged in to user with ID = 1
2021-07-17 12:19:37.392 D/NEXTACTIVTY: Valid user ID - Username = fred password is password_for_fred
2021-07-17 12:19:37.745 D/NEXTACTIVITY: Closing Cursor in onDestroy method
Basically you just need the
cursor.getInt([column position])
or
cursor.getString([column position])
to retrieve the data from the columns in the database. I made an example I hope this helps you. I'm not very familiar with programming language some cases so I can't argue more.
public class User {
private int id;
private String name;
private String password;
private boolean isLogged = false;
public User() {
}
public void setId(int id) {
this.id = id;
}
public int getId() {
return id;
}
public boolean isLogged() {
return isLogged;
}
public void setLogged(boolean x) {
this.isLogged = x;
}
}
Method to retrieve the Id requested you could just create a String or something..
public User checkLogin(String username, String password) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM user WHERE username=? AND password=? ", new String[] {username, password});
if (cursor.moveToFirst() || cursor.getCount() > 0) {
User user = new User();
user.setId(cursor.getInt(0));//if you created a primary key should be the first column
user.setLogged(true);
cursor.close();// * Closes the Cursor, releasing all of its resources and making it completely invalid.
db.close(); // * Releases a reference to the object, closing the object if the last reference* was released.
return user;
} else {
return null;
}
}
I recently launched an app on the android app store that contained a SQLite database.
I am now attempting to release an update of the app, and want to add more data into the existing database, however have come a bit unstuck. I have read answers on SO that outline making changes to the database itself, however I want my tables and columns to stay the same, only add new data in.
The data that i want to add to the database is pulled from CSV files in the Raw file, and originally loaded into the database when the user registers for the app.
I have a feeling I am going to need to implement the onUpgrade method, however should I be adding the new data from the CSV files in at that point as well? Is it a matter of simple updating the database version and using the onUpgrade to load the new data?
I am fairly new to SQLite DB, so any help would be hugely appreciated.
CourseDBHelper Code
public class CourseDBHelper extends SQLiteOpenHelper {
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "CourseDB";
// Create two table names
private static final String TABLE_COURSES = "courses";
// Universities Table Columns names
private static final String COURSE_NAME = "Course_name";
private static final String UNI_NAME = "Uni_name";
private static final String COURSE_DURATION = "Duration";
private static final String COURSE_STUDY_MODE = "Study_mode";
private static final String COURSE_QUALIFICATION = "Qualification";
private static final String COURSE_ENTRY_STANDARDS = "Entry_standards";
private static final String COURSE_GRADUATE_PROSPECTS = "Graduate_prospects";
private static final String COURSE_STUDENT_SATISFACTION = "Student_satisfaction";
private String CREATE_COURSES_TABLE = "CREATE TABLE courses" +
"(" +
"_id INTEGER PRIMARY KEY AUTOINCREMENT," +
"Course_name TEXT NOT NULL," +
"Uni_name TEXT NOT NULL," +
"Duration TEXT NOT NULL," +
"Study_mode TEXT NOT NULL," +
"Qualification TEXT NOT NULL," +
"Entry_standards TEXT NOT NULL," +
"Graduate_prospects TEXT NOT NULL," +
"Student_satisfaction TEXT NOT NULL" +
");";
private static final String[] COLUMNS = {
COURSE_NAME,
UNI_NAME,
COURSE_DURATION,
COURSE_STUDY_MODE,
COURSE_QUALIFICATION,
COURSE_ENTRY_STANDARDS,
COURSE_GRADUATE_PROSPECTS,
COURSE_STUDENT_SATISFACTION
};
public CourseDBHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// TODO: REMOVED NOT NULL FROM EVERY COLUMN FOR TEST PURPOSES, WILL NEED TO BE READDED
#Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(CREATE_COURSES_TABLE);
}
public void deleteAll()
{
SQLiteDatabase db = this.getWritableDatabase();
db.delete("courses", null, null);
db.execSQL("delete from " + "courses");
db.close();
}
// Getting one course by course name and uni name
public Course getCourse(String courseName, String uniName) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_COURSES, COLUMNS, " Course_name = ? AND Uni_name = ?",
new String[]{courseName, uniName},
null,
null,
null,
null);
if (cursor != null)
cursor.moveToFirst();
Course course = new Course();
/*
System.out.println(cursor.getString(0));
System.out.println(cursor.getString(1));
System.out.println(cursor.getString(2));
System.out.println(cursor.getString(3));
System.out.println(cursor.getString(4));
System.out.println(cursor.getString(5));
System.out.println(cursor.getString(6));
*/
course.setCourseName(cursor.getString(0));
course.setUniversity(cursor.getString(1));
course.setCourseDuration(cursor.getString(2));
course.setStudyMode(cursor.getString(3));
course.setQualification(cursor.getString(4));
course.setEntryStandards(cursor.getString(5));
course.setGradProspects(cursor.getString(6));
course.setStudentSatisfaction(cursor.getString(7));
return course;
}
public void addCourse(Course course)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COURSE_NAME, course.getCourseName());
values.put(UNI_NAME, course.getUniversity());
values.put(COURSE_DURATION, course.getCourseDuration());
values.put(COURSE_STUDY_MODE, course.getStudyMode());
values.put(COURSE_QUALIFICATION, course.getQualification());
values.put(COURSE_ENTRY_STANDARDS, course.getEntryStandards());
values.put(COURSE_GRADUATE_PROSPECTS, course.getGradProspects());
values.put(COURSE_STUDENT_SATISFACTION, course.getStudentSatisfaction());
db.insert(TABLE_COURSES,
null, //nullColumnHack
values);
db.close();
}
public ArrayList<Course> getAllCourses()
{
ArrayList<Course> courses = new ArrayList<>();
// 1. build the query
String query = "SELECT * FROM " + TABLE_COURSES;
// 2. get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(query, null);
// 3. go over each row, build course and add it to list
Course course;
if(cursor.moveToFirst()){
cursor.moveToNext();
do{
course = new Course();
course.setCourseName(cursor.getString(1));
course.setUniversity(cursor.getString(2));
course.setCourseDuration(cursor.getString(3));
course.setStudyMode(cursor.getString(4));
course.setQualification(cursor.getString(5));
course.setEntryStandards(cursor.getString(6));
course.setGradProspects(cursor.getString(7));
course.setStudentSatisfaction(cursor.getString(8));
// Add course to courses list
courses.add(course);
} while(cursor.moveToNext());
}
// return courses
return courses;
}
public int getDBCount()
{
SQLiteDatabase db = this.getWritableDatabase();
String count = "SELECT count(*) FROM courses";
Cursor mcursor = db.rawQuery(count, null);
mcursor.moveToFirst();
int icount = mcursor.getInt(0);
return icount;
}
public void deleteCourse(Course course) {
// 1. get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
// 2. delete
db.delete("courses", //table name
"Course_name = ? AND Uni_name = ?", // selections
new String[] { course.getCourseName(), course.getUniversity() }); //selections args
// 3. close
db.close();
}
#Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
}
Method that loads data from CSV file to SQlite DB
public void populateCourseDatabase(int id) {
// NOW POPULATE THE COURSE DATABASE FILE
inputStream = getResources().openRawResource(R.raw.coursesone);
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String word;
String cvsSplitBy = ",";
try{
while((word = reader.readLine()) != null){
Log.d(TAG, "constructing Course object from: " + word);
String[] segment = word.split(cvsSplitBy);
Course course = new Course();
course.setCourseName(segment[0]);
course.setUniversity(segment[1]);
course.setCourseDuration(segment[2]);
course.setStudyMode(segment[3]);
course.setQualification(segment[4]);
course.setEntryStandards(segment[5]);
course.setGradProspects(segment[6]);
course.setStudentSatisfaction(segment[7]);
myCourseDBHelper.addCourse(course);
progressBar.setProgress(count);
count = count + 1;
System.out.println("Sucessfully added: " + course.toString());
}
}
catch(IOException e1){
e1.printStackTrace();
System.out.println("SOMETHING WENT WRONG");
}
}
SQLiteOpenHelper onCreate() and onUpgrade() callbacks are invoked when the database is actually opened, for example by a call to getWritableDatabase().onCreate() is only run when the database file did not exist and was just created. onUpgrade() is only called when the database file exists but the stored version number is lower than requested in constructor.Increment the database version so that onUpgrade() is invoked.
Example pseudo code below
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
switch(oldVersion) {
case 1:
//upgrade logic from version 1 to 2
case 2:
//upgrade logic from version 2 to 3
case 3:
//upgrade logic from version 3 to 4
break;
default:
throw new IllegalStateException(
"onUpgrade() with unknown oldVersion " + oldVersion);
}
}
As I make the SQLite in android app, I made 3 class.
first is "MyDatabaseHelper.java" that make database and table.
second is "MyDB.java" that contain some functions(insert, cursor, update, delete).
third is "MyDBDefaultValues" that make default values using insert function in "MyDB.java".
The point is about transaction.
following the transaction manual(Android Database Transaction),
I need to insert "db.beginTransaction()" into "MyDB.java" because there are SQLitebase.
but I make the default values using insert function in other class(MyDBDefaultValues.java).
As a results, I don't know where to add transaction in my code. I know if I make a default code in "MyDB.java", I can add transaction in "MyDB.java".
but I want to separate "MyDB.java" and "MyDBDefaultValues.java".please tell me how to add transaction in my code.
Under is my code.
MyDatabaseHelper.java
public class MyDatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "Torticollis";
private static final int DATABASE_VERSION = 1;
// Database creation sql statement
private static final String DATABASE_CREATE = "create table Torticollis_Management(" +
"_id integer primary key autoincrement, " +
"date text not null, " + // store date to text type and convert between formats using the built-in date and time functions
"stretching1 text, " +
"stretching2 text, " +
"stretching3 text, " +
"stretching4 text, " +
"stretching5 text," +
"today_pain integer);";
public MyDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
Log.d("confirm", "this is first's god");
}
// Method is called during creation of the database
#Override
public void onCreate(SQLiteDatabase database) {
database.execSQL(DATABASE_CREATE);
}
// 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 Torticollis_Management");
onCreate(database);
}
}
MyDB.java
public class MyDB{
private MyDatabaseHelper dbHelper;
private SQLiteDatabase database;
public final static String Tor_TABLE = "Torticollis_Management"; // name of table
public final static String Tor_ID = "_id"; // id value for Torticollis
public final static String Tor_DATE = "date"; // date of Torticollis
public final static String Tor_STRETCHING1 = "stretching1"; // stretching1 of Torticollis
public final static String Tor_STRETCHING2 = "stretching2"; // stretching2 of Torticollis
public final static String Tor_STRETCHING3 = "stretching3"; // stretching3 of Torticollis
public final static String Tor_STRETCHING4 = "stretching4"; // stretching4 of Torticollis
public final static String Tor_STRETCHING5 = "stretching5"; // stretching5 of Torticollis
public final static String Tor_TODAY_PAIN = "today_pain"; // today_pain of Torticollis
// today_pain value's type is "String" but it's real type is "int"
/**
*
* #param context
*/
public MyDB(Context context){ // why do I add this 'context'??
dbHelper = new MyDatabaseHelper(context);
}
public long insert(String date, String stretching1, String stretching2, String stretching3,
String stretching4, String stretching5, int today_pain){
database = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
// values.put(Tor_ID, id); // "id" don't need to insert because that's made "autoincrement".
values.put(Tor_DATE, date);
values.put(Tor_STRETCHING1, stretching1);
values.put(Tor_STRETCHING2, stretching2);
values.put(Tor_STRETCHING3, stretching3);
values.put(Tor_STRETCHING4, stretching4);
values.put(Tor_STRETCHING5, stretching5);
values.put(Tor_TODAY_PAIN, today_pain); // why do I have to inert "integer"'s today_pain value into "String"'s Tor_TODAY_PAIN?
return database.insert(Tor_TABLE, null, values);
}
public Cursor cursor() {
database = dbHelper.getReadableDatabase();
String[] cols = new String[] {Tor_ID, Tor_DATE, Tor_STRETCHING1, Tor_STRETCHING2, Tor_STRETCHING3,
Tor_STRETCHING4, Tor_STRETCHING5, Tor_TODAY_PAIN};
Cursor mCursor = database.query(true, Tor_TABLE, cols, null, null, null, null, null, null);
if (mCursor != null) {mCursor.moveToFirst();}
return mCursor; // iterate to get each value.
}
public boolean update(String date, String stretching1, String stretching2, String stretching3,
String stretching4, String stretching5, int today_pain) {
database = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
// values.put(Tor_ID, id); // "id" don't need to insert because that exist only for counting
values.put("date", date);
values.put("stretching1", stretching1);
values.put("stretching2", stretching2);
values.put("stretching3", stretching3);
values.put("stretching4", stretching4);
values.put("stretching5", stretching5);
values.put("today_pain", today_pain);
database.update("Torticollis_Management", values, "date = ?", new String[]{date}); // need to know this coding
return true;
}
public Integer delete(String date) {
database = dbHelper.getWritableDatabase();
return database.delete("Torticollis_Management", "id = ?", new String[]{date}); // need to know this coding
}
}
MyDBDefaultValues.java
public class MyDBDefaultValues {
MyDB mydb;
public MyDBDefaultValues(Context context){ // why do I have to write the word "context". what's the mean of "context"?
mydb = new MyDB(context);
insertDefaultValues(); // insert default values if there is no data.
}
public void insertDefaultValues() {
Cursor cursor = mydb.cursor();
cursor.moveToLast();
int count = cursor.getCount();
if(count > 0) {
// do nothing
} else { // insert default values if there is no data.
mydb.insert("2016-07-01", "X", "X", "X", "X", "X", 0);
mydb.insert("2016-07-02", "X", "X", "X", "X", "X", 0);
mydb.insert("2016-07-03", "X", "X", "X", "X", "X", 0);
mydb.insert("2016-07-04", "X", "X", "X", "X", "X", 0);
}
}
}
In general, you should put transactions into the outermost function(s); this is both correct (multiple DB operations are then atomic), and more efficient:
public void insertDefaultValues() {
mydb.beginTransaction();
try {
if (mydb.cursor().getCount() == 0) {
mydb.insert(...);
...
}
mydb.setTransactionSuccessful();
} finally {
mydb.endTransaction();
}
}
This requires that you add wrappers for the beginTransaction() etc. calls to your MyDB class.
This question already has answers here:
Ship an application with a database
(15 answers)
Closed 7 years ago.
I have a static sqlite db. How could I include it into the app? Where should i put it in my project folder? How should I access it from DatabaseHandler?
Everything I found on the web was using sqlite only for creating a new db and storing user or temp data in it, but not using existing db with predefined data.
Official Google docs does not tell how to do that.
Handling this case is basically just doing a file copy.
The tricky part is
To create the database when needed only (otherwise just open it)
To implement the upgrade logic
I wrote a sample Helper class that demonstrate how to load a database from your assets.
public abstract class SQLiteAssetHelper extends SQLiteOpenHelper {
// ----------------------------------
// CONSTANTS
// ----------------------------------
private static final String DATABASE_DIR_NAME = "databases";
// ----------------------------------
// ATTRIBUTES
// ----------------------------------
private final Context mContext;
private final CursorFactory mFactory;
private SQLiteDatabase mDatabase;
private String mDatabaseName;
private String mDatabaseAssetPath;
private String mDatabaseDiskPath;
private boolean mIsProcessingDatabaseCreation; // Database creation may take some time
// ----------------------------------
// CONSTRUCTORS
// ----------------------------------
public SQLiteAssetHelper(Context context, String name, CursorFactory factory, String destinationPath, int version) {
super(context, name, factory, version);
mContext = context;
mFactory = factory;
mDatabaseName = name;
mDatabaseAssetPath = DATABASE_DIR_NAME + "/" + name;
if (destinationPath == null) {
mDatabaseDiskPath = context.getApplicationInfo().dataDir + "/" + DATABASE_DIR_NAME;
} else {
mDatabaseDiskPath = destinationPath;
}
}
// ----------------------------------
// OVERRIDEN METHODS
// ----------------------------------
#Override
public synchronized SQLiteDatabase getWritableDatabase() {
if (mDatabase != null && mDatabase.isOpen() && !mDatabase.isReadOnly()) {
// the database is already open and writable
return mDatabase;
}
if (mIsProcessingDatabaseCreation) {
throw new IllegalStateException("getWritableDatabase is still processing");
}
SQLiteDatabase db = null;
boolean isDatabaseLoaded = false;
try {
mIsProcessingDatabaseCreation = true;
db = createOrOpenDatabase();
// you should probably check for database new version and process upgrade if necessary
onOpen(db);
isDatabaseLoaded = true;
return db;
} catch (IOException e) {
e.printStackTrace();
return null;
} finally {
mIsProcessingDatabaseCreation = false;
if (isDatabaseLoaded) {
if (mDatabase != null) {
try {
mDatabase.close();
} catch (Exception e) {
e.printStackTrace();
}
}
mDatabase = db;
} else {
if (db != null) db.close();
}
}
}
#Override
public final void onCreate(SQLiteDatabase db) {
// getWritableDatabase() actually handles database creation so nothing to code here
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO implement your upgrade logic here
}
// ----------------------------------
// PRIVATE METHODS
// ----------------------------------
private void copyDatabaseFromAssets() throws IOException {
String dest = mDatabaseDiskPath + "/" + mDatabaseName;
String path = mDatabaseAssetPath;
InputStream is = mContext.getAssets().open(path);
File databaseDestinationDir = new File(mDatabaseDiskPath + "/");
if (!databaseDestinationDir.exists()) {
databaseDestinationDir.mkdir();
}
IOUtils.copy(is, new FileOutputStream(dest));
}
private SQLiteDatabase createOrOpenDatabase() throws IOException {
SQLiteDatabase db = null;
File file = new File (mDatabaseDiskPath + "/" + mDatabaseName);
if (file.exists()) {
db = openDatabase();
}
if (db != null) {
return db;
} else {
copyDatabaseFromAssets();
db = openDatabase();
return db;
}
}
private SQLiteDatabase openDatabase() {
try {
SQLiteDatabase db = SQLiteDatabase.openDatabase(
mDatabaseDiskPath + "/" + mDatabaseName, mFactory, SQLiteDatabase.OPEN_READWRITE);
return db;
} catch (SQLiteException e) {
e.printStackTrace();
return null;
}
}
// ----------------------------------
// NESTED CLASSES
// ----------------------------------
private static class IOUtils {
private static final int BUFFER_SIZE = 1024;
public static void copy(InputStream in, OutputStream outs) throws IOException {
int length;
byte[] buffer = new byte[BUFFER_SIZE];
while ((length = in.read(buffer)) > 0) {
outs.write(buffer, 0, length);
}
outs.flush();
outs.close();
in.close();
}
}; // IOUtils
}
Then you only have to create a class that extends from the one above like this :
public class MyDbHelper extends SQLiteAssetHelper {
// ----------------------------------
// CONSTANTS
// ----------------------------------
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_FILE_NAME = "test.db";
// ----------------------------------
// CONSTRUCTORS
// ----------------------------------
public MyDbHelper(Context context) {
super(context, DATABASE_FILE_NAME, null, context.getFilesDir().getAbsolutePath(), DATABASE_VERSION);
}
}
Each time you will call getWritableDatabase() from your MyDbHelper instance, it will do all the copy/open stuff for you and return the writable database.
As I said before, I did not implement the upgrade() method in this sample, you'll have to.
I also didn't implement getReadableDatabase() since I usually only use getWritableDatabase(). You may need to do it.
If you want to test it, just do the following:
Copy the code above
Create a folder in your assets called "databases" and insert your sqlite database file in it
In MyDatabaseHelper, change the value of the DATABASE_FILE_NAME constants with the name of the database in the asset folder
Don't forget to instantiate the MyDatabaseHelper and call for getWritableDatabse()
Hope this helped.
I have a sortid row in my table to have a custom order of my data.
in my SQLiteOpenHelper class, i have a drop() function which calls .update(), and in loadCities() the rows are queried but i get the old sortId.
here are parts of my code:
public class TimesHelper extends SQLiteOpenHelper {
private static final String TABLE_CREATE = "CREATE TABLE " + TABLE_NAME
+ " (" + KEY__ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ [...] + KEY_SORTID + " INTEGER);";
private SQLiteDatabase mDB;
private Handler mHandler;
public SQLiteDatabase getDB() {
if (mDB == null) {
mDB = getWritableDatabase();
} else {
mHandler.removeCallbacks(mClose);
}
//useful, but i am not sure wether this is good practise, please comment...
mHandler.postDelayed(mClose, 500);
return mDB;
}
private Runnable mClose = new Runnable() {
#Override
public void run() {
if (mDB != null) {
mDB.close();
mDB = null;
}
}
};
public void drop(int from, int to) {
List<Integer> keys = new ArrayList<Integer>(Times.Cities.keySet());
Integer key = keys.get(from);
keys.remove(key);
keys.add(to, key);
getDB().beginTransaction();
for (Integer i : keys) {
ContentValues val = new ContentValues();
val.put(KEY_SORTID, keys.indexOf(i));
getDB().update(TABLE_NAME, val,
KEY__ID + "=" + i, null);//returning 1
}
getDB().endTransaction();
loadCities();
}
public void loadCities() {
HashMap<Integer, Times> cities = Times.Cities;
cities.clear();
Cursor c = getDB().query(TABLE_NAME, null, null, null, null, null,
KEY_SORTID);
c.moveToFirst();
if (c.isAfterLast()) {
c.close();
return;
}
do {
int s = c.getInt(c.getColumnIndex(KEY_SORTID));
int id = c.getInt(c.getColumnIndex(KEY__ID));
//here i still have the old values...
//do whatever
}
} while (c.moveToNext());
c.close();
}
}
i tried anything, but without success...
Metin Kale
You forgot setTransactionSuccessful(). Calling endTransaction() without it rolls back any changes done within the transaction.
The preferred, exception-safe pattern to handle transactions is
beginTransaction();
try {
// db operations...
setTransactionSuccessful(); // didn't throw so far
} finally {
endTransaction(); // rollback or commit
}