没有这样的 table:从资产复制数据库时出现 table1 错误
No such table: table1 error when copying database from assets
我在 assets/databases 中存储了一个名为 myDatabase.db
的数据库,我想使用此处的代码将其复制到内部存储:
public class DatabaseOpener extends SQLiteOpenHelper {
private static String DB_PATH;
private static String DB_NAME = "table1.db";
private static int DB_VERSION = 4;
private SQLiteDatabase myDataBase;
private static Context myContext;
private static DatabaseOpener instance;
private DatabaseOpener(Context context) {
super(context, DB_NAME, null, DB_VERSION);
this.myContext = context;
}
public static synchronized DatabaseOpener getInstance(Context context) {
if (instance==null) {
instance = new DatabaseOpener(context);
}
if(Build.VERSION.SDK_INT >= 4.2) {
DB_PATH = myContext.getApplicationInfo().dataDir + "/databases/";
} else {
DB_PATH = "/data/data/" + myContext.getPackageName() + "/databases/";
}
return instance;
}
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if(dbExist) {
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
File file = new File(myPath);
if (file.exists() && !file.isDirectory()) {
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
}catch(SQLiteException e){
e.printStackTrace();
}
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 = 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[1024];
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 {
String myPath = DB_PATH + DB_NAME;
File file = new File(myPath);
if (file.exists() && !file.isDirectory()) {
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
以上代码成功运行,直到我卸载了我的应用程序。问题是数据库没有复制成功。我的文件没问题,但是当它被复制到路径中时,如果我拿走它并在 DB Browser 中打开它,它没有表格。如果我将它推入模拟器,它会再次运行,但我无法将它推入无根设备。唯一的方法是在路径中创建一个数据库文件并从资产中复制一个。那么,我做错了什么?
另外,这就是我调用 DatabaseOpener class:
的方式
DatabaseOpener db = DatabaseOpener.getInstance(context);
try {
db.createDataBase();
} catch (IOException e) {
throw new Error ("Unable to create database");
}
try {
db.openDataBase();
}catch(SQLException sqle){
throw sqle;
}
Object object = db.getObjectByName(name);
db.close();
return object;
编辑: 我收到的错误是 android.database.sqlite.SQLiteException: no such table: table1 (code 1): , while compiling
。
卸载应用程序后android删除与应用程序相关的所有本地数据存储,因此 SQLDatabase 将被销毁。
并且当您重新安装应用程序时,您是在创建 table 之前尝试访问它,因此会引发错误。确保在操作其数据之前创建 table。
你需要写在onCreate(SQLiteDatabase db)
db.execSQL(CREATE_TABLE_QUERY);
我用下面的代码解决了这个问题:
public DatabaseOpener(Context context) throws IOException {
super(context, DB_NAME, null, DB_VERSION);
this.myContext = context;
if (Build.VERSION.SDK_INT >= 4.2) {
DB_PATH = myContext.getApplicationInfo().dataDir + "/databases/";
} else {
DB_PATH = "/data/data/" + myContext.getPackageName() + "/databases/";
}
boolean dbexist = checkDataBase();
if (dbexist) {
openDataBase();
} else {
System.out.println("Database doesn't exist");
createDataBase();
}
}
public void createDataBase() throws IOException {
boolean dbexist = checkDataBase();
if (dbexist) {
// System.out.println(" Database exists.");
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase() {
boolean checkdb = false;
try {
String myPath = DB_PATH + DB_NAME;
File dbfile = new File(myPath);
checkdb = dbfile.exists();
} catch (SQLiteException e) {
System.out.println("Database doesn't exist");
}
return checkdb;
}
private void copyDataBase() throws IOException {
// Open your local db as the input stream
InputStream myinput = myContext.getAssets().open("databases/" + 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(DB_PATH + DB_NAME);
// transfer byte to inputfile to 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();
}
public void openDataBase() throws SQLException {
// Open the database
String mypath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(mypath, null, SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
我在 assets/databases 中存储了一个名为 myDatabase.db
的数据库,我想使用此处的代码将其复制到内部存储:
public class DatabaseOpener extends SQLiteOpenHelper {
private static String DB_PATH;
private static String DB_NAME = "table1.db";
private static int DB_VERSION = 4;
private SQLiteDatabase myDataBase;
private static Context myContext;
private static DatabaseOpener instance;
private DatabaseOpener(Context context) {
super(context, DB_NAME, null, DB_VERSION);
this.myContext = context;
}
public static synchronized DatabaseOpener getInstance(Context context) {
if (instance==null) {
instance = new DatabaseOpener(context);
}
if(Build.VERSION.SDK_INT >= 4.2) {
DB_PATH = myContext.getApplicationInfo().dataDir + "/databases/";
} else {
DB_PATH = "/data/data/" + myContext.getPackageName() + "/databases/";
}
return instance;
}
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if(dbExist) {
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
File file = new File(myPath);
if (file.exists() && !file.isDirectory()) {
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
}catch(SQLiteException e){
e.printStackTrace();
}
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 = 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[1024];
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 {
String myPath = DB_PATH + DB_NAME;
File file = new File(myPath);
if (file.exists() && !file.isDirectory()) {
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
以上代码成功运行,直到我卸载了我的应用程序。问题是数据库没有复制成功。我的文件没问题,但是当它被复制到路径中时,如果我拿走它并在 DB Browser 中打开它,它没有表格。如果我将它推入模拟器,它会再次运行,但我无法将它推入无根设备。唯一的方法是在路径中创建一个数据库文件并从资产中复制一个。那么,我做错了什么? 另外,这就是我调用 DatabaseOpener class:
的方式 DatabaseOpener db = DatabaseOpener.getInstance(context);
try {
db.createDataBase();
} catch (IOException e) {
throw new Error ("Unable to create database");
}
try {
db.openDataBase();
}catch(SQLException sqle){
throw sqle;
}
Object object = db.getObjectByName(name);
db.close();
return object;
编辑: 我收到的错误是 android.database.sqlite.SQLiteException: no such table: table1 (code 1): , while compiling
。
卸载应用程序后android删除与应用程序相关的所有本地数据存储,因此 SQLDatabase 将被销毁。
并且当您重新安装应用程序时,您是在创建 table 之前尝试访问它,因此会引发错误。确保在操作其数据之前创建 table。
你需要写在onCreate(SQLiteDatabase db)
db.execSQL(CREATE_TABLE_QUERY);
我用下面的代码解决了这个问题:
public DatabaseOpener(Context context) throws IOException {
super(context, DB_NAME, null, DB_VERSION);
this.myContext = context;
if (Build.VERSION.SDK_INT >= 4.2) {
DB_PATH = myContext.getApplicationInfo().dataDir + "/databases/";
} else {
DB_PATH = "/data/data/" + myContext.getPackageName() + "/databases/";
}
boolean dbexist = checkDataBase();
if (dbexist) {
openDataBase();
} else {
System.out.println("Database doesn't exist");
createDataBase();
}
}
public void createDataBase() throws IOException {
boolean dbexist = checkDataBase();
if (dbexist) {
// System.out.println(" Database exists.");
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase() {
boolean checkdb = false;
try {
String myPath = DB_PATH + DB_NAME;
File dbfile = new File(myPath);
checkdb = dbfile.exists();
} catch (SQLiteException e) {
System.out.println("Database doesn't exist");
}
return checkdb;
}
private void copyDataBase() throws IOException {
// Open your local db as the input stream
InputStream myinput = myContext.getAssets().open("databases/" + 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(DB_PATH + DB_NAME);
// transfer byte to inputfile to 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();
}
public void openDataBase() throws SQLException {
// Open the database
String mypath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(mypath, null, SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}