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나는 SQLite 데이터베이스를 사용하는 응용 프로그램에서 일하고 있어요. 나는 두 개의 다른 sqlite 데이터베이스를 생성하고 assets 폴더에서 복사하는 사용자 정의 DatabaseHelper 클래스를 가지고 있습니다. 내가 가질 수있는 문제는 나는 두 개의 데이터베이스가안드로이드 데이터베이스를 변경
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DataBaseHelper extends SQLiteOpenHelper{
private static SQLiteDatabase sqliteDb;
private static DataBaseHelper instance;
private static final int DATABASE_VERSION = 1;
// the default database path is :
// /data/data/pkgNameOfYourApplication/databases/
private static String DB_PATH_PREFIX = "/data/data/";
private static String DB_PATH_SUFFIX = "/databases/";
private static final String TAG = "DataBaseHelper";
private Context context;
/***
* Contructor
*
* @param context
* : app context
* @param name
* : database name
* @param factory
* : cursor Factory
* @param version
* : DB version
*/
public DataBaseHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, name, factory, version);
this.context = context;
Log.i(TAG, "Create or Open database : " + name);
}
/***
* Initialize method
*
* @param context
* : application context
* @param databaseName
* : database name
*/
public static void initialize(Context context, String databaseName) {
if (instance == null) {
/**
* Try to check if there is an Original copy of DB in asset
* Directory
*/
if (!checkDatabase(context, databaseName)) {
// if not exists, I try to copy from asset dir
try {
copyDataBase(context, databaseName);
} catch (IOException e) {
Log.e(TAG,"Database "+ databaseName+" does not exists and there is no Original Version in Asset dir");
}
}
Log.i(TAG, "Try to create instance of database (" + databaseName
+ ")");
instance = new DataBaseHelper(context, databaseName,
null, DATABASE_VERSION);
sqliteDb = instance.getWritableDatabase();
Log.i(TAG, "instance of database (" + databaseName + ") created !");
}
}
/***
* Static method for getting singleton instance
*
* @param context
* : application context
* @param databaseName
* : database name
* @return : singleton instance
*/
public static final DataBaseHelper getInstance(
Context context, String databaseName) {
initialize(context, databaseName);
return instance;
}
/***
* Method to get database instance
*
* @return database instance
*/
public SQLiteDatabase getDatabase() {
return sqliteDb;
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.d(TAG, "onCreate : nothing to do");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.d(TAG, "onUpgrade : nothing to do");
}
/***
* Method for Copy the database from asset directory to application's data
* directory
*
* @param databaseName
* : database name
* @throws IOException
* : exception if file does not exists
*/
public void copyDataBase(String databaseName) throws IOException {
copyDataBase(context, databaseName);
}
/***
* Static method for copy the database from asset directory to application's
* data directory
*
* @param aContext
* : application context
* @param databaseName
* : database name
* @throws IOException
* : exception if file does not exists
*/
private static void copyDataBase(Context aContext, String databaseName)
throws IOException {
// Open your local db as the input stream
InputStream myInput = aContext.getAssets().open(databaseName);
// Path to the just created empty db
String outFileName = getDatabasePath(aContext, databaseName);
Log.i(TAG, "Check if create dir : " + DB_PATH_PREFIX
+ aContext.getPackageName() + DB_PATH_SUFFIX);
// if the path doesn't exist first, create it
File f = new File(DB_PATH_PREFIX + aContext.getPackageName()
+ DB_PATH_SUFFIX);
if (!f.exists())
f.mkdir();
Log.i(TAG, "Trying to copy local DB to : " + outFileName);
// 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[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
// Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
Log.i(TAG, "DB (" + databaseName + ") copied!");
}
/***
* Method to check if database exists in application's data directory
*
* @param databaseName
* : database name
* @return : boolean (true if exists)
*/
public boolean checkDatabase(String databaseName) {
return checkDatabase(context, databaseName);
}
/***
* Static Method to check if database exists in application's data directory
*
* @param aContext
* : application context
* @param databaseName
* : database name
* @return : boolean (true if exists)
*/
private static boolean checkDatabase(Context aContext, String databaseName) {
SQLiteDatabase checkDB = null;
try {
String myPath = getDatabasePath(aContext, databaseName);
Log.i(TAG, "Trying to conntect to : " + myPath);
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
Log.i(TAG, "Database " + databaseName + " found!");
checkDB.close();
} catch (SQLiteException e) {
Log.i(TAG, "Database " + databaseName + " does not exists!");
}
return checkDB != null ? true : false;
}
/***
* Method that returns database path in the application's data directory
*
* @param databaseName
* : database name
* @return : complete path
*/
@SuppressWarnings("unused")
private String getDatabasePath(final String databaseName) {
return getDatabasePath(context, databaseName);
}
/***
* Static Method that returns database path in the application's data
* directory
*
* @param aContext
* : application context
* @param databaseName
* : database name
* @return : complete path
*/
private static String getDatabasePath(Context aContext, String databaseName) {
return DB_PATH_PREFIX + aContext.getPackageName() + DB_PATH_SUFFIX
+ databaseName;
}
public boolean executeQuery(String tableName,ContentValues values){
return execQuery(tableName,values);
}
private static boolean execQuery(String tableName,ContentValues values){
sqliteDb = instance.getWritableDatabase();
sqliteDb.insert(tableName, null, values);
return true;
}
public boolean updateSQL(String tableName,String key,String value){
return updateData(tableName,key,value);
}
private static boolean updateData(String tableName,String key,String value){
sqliteDb = instance.getWritableDatabase();
String where = "";
ContentValues values = new ContentValues();
values.put(key, value);
values.put(key, value);
sqliteDb.update(tableName, values, where, new String[] {"3"});
return true;
}
public boolean deleteSQL(String tableName){
return deleteData(tableName);
}
private static boolean deleteData(String tableName){
sqliteDb = instance.getWritableDatabase();
String where = "";
sqliteDb.delete(tableName, where, new String[] {"5"});
return true;
}
public Cursor executeSQLQuery(String query){
return sqliteDb.rawQuery(query,null);
}
/**
* Make queries
*
*/
}
: 첫 번째는 두 번째 user.sqlitesystem.sqlite하고 데이터베이스가 다른 situations.Here에서 사용할 수있는 't 세트처럼 내 DatabaseHelper 클래스는 모습입니다. 내 응용 프로그램이 시작될 때 나는 첫 번째 초기화 해요 : 나는 사용자의 데이터베이스 같은 방식으로, 내 응용 프로그램에서 사용자가 처음 로그인을 초기화하고있어
dbHelper = new DataBaseHelper(this, "system.sqlite", null, 1);
DataBaseHelper.initialize(this, "system.sqlite");
dbHelper.checkDatabase("system.sqlite");
. 로그인 후 은 내가 dB의 양쪽에서 일부 데이터를 삽입 할 필요가 몇 비 활동 수업이 있습니다
ContentValues values = new ContentValues();
values.put("objectId", 75);
values.put("objectOid", "boom");
values.put("serverName", "shit");
values.put("locale", "en_US");
values.put("deviceId", 45);
dbHelper.executeQuery("users",values);
을하지만 문제는 주변에 비해 첫 번째 클래스의 경우에도 개방 내 system.sqlite 그것은 .. 그리고 그것은 여전히 시스템 db에 쓰려고 다른 클래스에서 user.sqlite를 열려고합니다. 예 :
dbHelper = new DataBaseHelper(context, "system.sqlite", null, 1);
dbHelper.initialize(context, "system.sqlite");
dbHelper.getWritableDatabase();
//do some work
dbHelper.close();
실제로 작동하지 않습니다. 제안 사항 어떻게하면 일을 시작할 수 있습니까?
정적 필드를 모두 제거하면이 줄에서 예외가 발생합니다. return sqliteDb.rawQuery (query, null); –
또한 정적 필드를 참조하는 코드를 수정해야합니다. –
지금이 줄에 붙어 있습니다 : return DB_PATH_PREFIX + aContext.getPackageName() + DB_PATH_SUFFIX + databaseName; --- 어떤 NullPointerException 던지고있다. –