访问外部 SQLite 数据库时出错
Error Accessing external SQLite database
我有一个名为 example.db 的外部 sqlite 数据库,我正在尝试使用 OrmLite 创建它。我在网上搜索了一下,大家都推荐了这个教程http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/
所以我遵循它并且工作得很好,但是当我尝试使用 OrmLite 做同样的事情时,我无法从外部文件创建我自己的数据库 (example.db)。我发现当我调用方法 createDatabase() 时,数据库已经创建,并且当我在没有 OrmLite 的情况下使用 OpenHelperDatabase 时它没有发生。
有人知道吗?
密码是:
//imports
public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
private static String DB_PATH = "/data/data/com.example/databases/";
private static String DB_NAME = "example.db";
private static final int DATABASE_VERSION = 1;
private SQLiteDatabase exampleDB;
private final Context context;
public DatabaseHelper(Context context) {
super(context, DB_NAME, null, DATABASE_VERSION);
this.context = context;
}
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if(dbExist){
Log.i(DatabaseHelper.class.getName(), "Database already exist!!! Here is the problem");
}else{
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = context.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[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
@Override
public void onCreate(SQLiteDatabase db, ConnectionSource connectionSource) {
Log.i(DatabaseHelper.class.getName(), "onCreate");
try {
createDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, ConnectionSource connectionSource, int oldVersion, int newVersion) {
//TODO
}
@Override
public synchronized void close() {
if(exampleDB != null)
exampleDB.close();
super.close();
}
}
我想你只需要将名称加上扩展名 example.db
发现问题了,我已经放弃了,于是在研究另一个ORM,叫ActiveAndroid。当我看到此页面时,我正在阅读文档页面:https://github.com/pardom/ActiveAndroid/wiki/Pre-populated-databases 和以下语句:将所有主键字段重命名为命名 Id(不像标准 Android 数据库那样使用 _id)。
所以我修改了我的数据库并尝试使用上面的代码并且它运行良好,问题解决了。但是我仍然不知道为什么 Android 复制数据库以及为什么我们必须更改 id 列的名称。
createDataBase 方法
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase() {
File dbFile = new File(DB_PATH + DB_NAME);
return dbFile.exists();
}
复制数据库方法
private void copyDataBase() throws IOException {
InputStream myInput = context.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
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();
}
打开数据库方法
public void openDataBase () throws SQLException{
String path = DB_PATH +DB_NAME;
db =SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS | SQLiteDatabase.CREATE_IF_NECESSARY);
}
从数据库中检索数据
public Cursor getData() {
String myPath = DB_PATH + DB_NAME;
db = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
Cursor c = db.rawQuery("SELECT * FROM info", null);
return c;
}
将数据插入数据库
public void addUser(Astro contact) {
// SQLiteDatabase db = this.getWritableDatabase();
String myPath = DB_PATH + DB_NAME;
db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_Date, contact.get_date()); // Contact Name
values.put(KEY_Time, contact.get_time()); // Contact Phone
// Inserting Row
db.insert(TABLE_ASTRO, null, values);
//2nd argument is String containing nullColumnHack
db.close(); // Closing database connection
}
我有一个名为 example.db 的外部 sqlite 数据库,我正在尝试使用 OrmLite 创建它。我在网上搜索了一下,大家都推荐了这个教程http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/
所以我遵循它并且工作得很好,但是当我尝试使用 OrmLite 做同样的事情时,我无法从外部文件创建我自己的数据库 (example.db)。我发现当我调用方法 createDatabase() 时,数据库已经创建,并且当我在没有 OrmLite 的情况下使用 OpenHelperDatabase 时它没有发生。
有人知道吗?
密码是:
//imports
public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
private static String DB_PATH = "/data/data/com.example/databases/";
private static String DB_NAME = "example.db";
private static final int DATABASE_VERSION = 1;
private SQLiteDatabase exampleDB;
private final Context context;
public DatabaseHelper(Context context) {
super(context, DB_NAME, null, DATABASE_VERSION);
this.context = context;
}
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if(dbExist){
Log.i(DatabaseHelper.class.getName(), "Database already exist!!! Here is the problem");
}else{
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = context.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[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
@Override
public void onCreate(SQLiteDatabase db, ConnectionSource connectionSource) {
Log.i(DatabaseHelper.class.getName(), "onCreate");
try {
createDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, ConnectionSource connectionSource, int oldVersion, int newVersion) {
//TODO
}
@Override
public synchronized void close() {
if(exampleDB != null)
exampleDB.close();
super.close();
}
}
我想你只需要将名称加上扩展名 example.db
发现问题了,我已经放弃了,于是在研究另一个ORM,叫ActiveAndroid。当我看到此页面时,我正在阅读文档页面:https://github.com/pardom/ActiveAndroid/wiki/Pre-populated-databases 和以下语句:将所有主键字段重命名为命名 Id(不像标准 Android 数据库那样使用 _id)。
所以我修改了我的数据库并尝试使用上面的代码并且它运行良好,问题解决了。但是我仍然不知道为什么 Android 复制数据库以及为什么我们必须更改 id 列的名称。
createDataBase 方法
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase() {
File dbFile = new File(DB_PATH + DB_NAME);
return dbFile.exists();
}
复制数据库方法
private void copyDataBase() throws IOException {
InputStream myInput = context.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
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();
}
打开数据库方法
public void openDataBase () throws SQLException{
String path = DB_PATH +DB_NAME;
db =SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS | SQLiteDatabase.CREATE_IF_NECESSARY);
}
从数据库中检索数据
public Cursor getData() {
String myPath = DB_PATH + DB_NAME;
db = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
Cursor c = db.rawQuery("SELECT * FROM info", null);
return c;
}
将数据插入数据库
public void addUser(Astro contact) {
// SQLiteDatabase db = this.getWritableDatabase();
String myPath = DB_PATH + DB_NAME;
db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_Date, contact.get_date()); // Contact Name
values.put(KEY_Time, contact.get_time()); // Contact Phone
// Inserting Row
db.insert(TABLE_ASTRO, null, values);
//2nd argument is String containing nullColumnHack
db.close(); // Closing database connection
}