package com.android.database;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseConnectionAPI extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private final static String DB_PATH = "/data/data/com.android.database/databases/";
private final static String DB_NAME = "demo.sqlite";
private final Context myContext;
private static SQLiteDatabase db;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public DatabaseConnectionAPI(Context context)
{
super(context, DB_NAME, null, 1);
this.myContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException
{
boolean dbExist = checkDataBase();
if(dbExist)
{
//do nothing - database already exist
}
else
{
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
try
{
copyDataBase();
}
catch (IOException e)
{
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[2048];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException{
try
{
db.close();
}
catch(Exception e)
{
System.out.println("no database connected to close");
}
//Open the database
String myPath = DB_PATH + DB_NAME;
db = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if(db != null)
db.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
/**
* Use this function to set the value of a particular column
*
* @param columnName The column name whose value is to be changed
* @param newColumnValue The value to be replaced in the column
* @param whereColumnName The column name to be compared with the where clause
* @param whereColumnValue The value to be compared in the where clause
*/
void onUpdateSet(String columnName, String newColumnValue, String[] whereColumnName, String[] whereColumnValue){
String expanded_ColumnNames = new String(whereColumnName[0]);
String expanded_ColumnValues = new String(whereColumnValue[0]);
for(int i=1;i {
expanded_ColumnNames = expanded_ColumnNames+","+whereColumnName[i];
expanded_ColumnValues = expanded_ColumnValues+","+whereColumnValue[i];
}
try
{
openDataBase();
db.execSQL("update recipe set \""+columnName+"\" = \""+newColumnValue+"\" where \""+expanded_ColumnNames+"\" = \""+expanded_ColumnValues+"\"");
}
catch(Exception e)
{
System.out.println("Update couldnt complete "+e);
}
}
/**
* Query the given table, returning a Cursor over the result set.
*
* @param table The table name to compile the query against.
* @param columns A list of which columns to return. Passing null will return all columns,
* which is discouraged to prevent reading data from storage that isn't going to be used.
* @param selection A filter declaring which rows to return, formatted
* as an SQL WHERE clause (excluding the WHERE itself). Passing null
* will return all rows for the given table.
* @param selectionArgs You may include ?s in selection, which will be
* replaced by the values from selectionArgs, in order that they appear
* in the selection. The values will be bound as Strings.
* @param groupBy A filter declaring how to group rows, formatted as an
* SQL GROUP BY clause (excluding the GROUP BY itself). Passing null
* will cause the rows to not be grouped.
* @param having A filter declare which row groups to include in the
* cursor, if row grouping is being used, formatted as an SQL HAVING
* clause (excluding the HAVING itself). Passing null will cause all
* row groups to be included, and is required when row grouping is
* not being used.
* @param orderBy How to order the rows, formatted as an SQL
* ORDER BY clause (excluding the ORDER BY itself). Passing
* null will use the default sort order, which may be unordered.
* @return A Cursor object, which is positioned before the first entry
*/
Cursor onQueryGetCursor(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy)
{
Cursor query = null;
try
{
openDataBase();
query = db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy);
System.out.println("@@@@@ Query is :"+query);
}
catch(Exception e)
{
System.out.println("Query couldnt complete "+e);
}
return query;
}
/**
* Use this method to search a particular String in the provided field.
*
*
* @param columns The array of columns to be returned
* @param table The table name
* @param whereColumn The where clause specifying a particular columns
* @param keyword The keyword which is to be searched
*
* @return The cursor containing the result of the query
*/
Cursor onSearchGetCursor(String[] columns, String table, String[] whereColumn, String keyword)
{
String expColumns = new String(columns[0]);
Cursor rawquery=null;
for(int i=1;i expColumns = expColumns+","+columns[i];
try
{
openDataBase();
rawquery = db.rawQuery("SELECT "+expColumns+" from "+table+" where "+whereColumn[0]+" like \"%"+keyword+"%\" or "+whereColumn[1]+" like \"%"+keyword+"%\" or "+whereColumn[2]+" like \"%"+keyword+"%\"", null);
}
catch(Exception e)
{
System.out.println("Raw Query couldnt complete "+e);
}
return rawquery;
}
}
