我的数据库名称为：MyDb.sqlite
然后在我的数据库文件中有2个表
1个用户表
row1 id_users (primary key,auto increment,int)
row2 username (varchar)
and value is empty
2个android_metabata表
row1 locale (text) then values is en_US
我将数据库放入资产文件夹
JAVA课程
public class DataBaseHelper extends SQLiteOpenHelper{
private static String DB_PATH = "/data/data/com.example/databases/";
private static String DB_NAME = "MyDb.db";
private SQLiteDatabase myDataBase;
private final Context myContext;
private static DataBaseHelper sInstance = null;
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}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 = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
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();
}
public void openDataBase() throws SQLException{
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
public Cursor select(String query) throws SQLException {
return myDataBase.rawQuery(query, null);
}
public void insert(String table, ContentValues values) throws SQLException {
myDataBase.insert(table, null, values);
}
public void delete(String table, String where) throws SQLException {
myDataBase.delete(table, where, null);
}
public void update(String table, ContentValues values, String where) {
myDataBase.update(table, values, where, null);
}
public void sqlCommand(String command) {
myDataBase.execSQL(command);
}
@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) {
}
public static DataBaseHelper instance() {
/*
if (sInstance == null) {
sInstance = new DataBaseManager();
}
*/
return sInstance;
}
}
进程复制成功然后我查看文件夹data / data / my_package_name / databases 使用此tutorial
但我的表用户无法复制并且我的表android_metadata复制成功，为什么？
感谢。
答案 0 :(得分：1)
试试这段代码：
public DataBaseHelper(Context context)
{
super(context, DB_NAME, null, 1);
this.mContext = context;
DB_PATH="/data/data/" + context.getPackageName() + "/databases/";
}
public void openDataBase() throws SQLException
{
Log.e("Open", "open Database");
mDbHelper = new DataBaseHelper(mContext);
mDataBase = mDbHelper.getWritableDatabase();
}
@Override
public synchronized SQLiteDatabase getWritableDatabase()
{
SQLiteDatabase db = null;
if (!existsDataBase()) {
try
{
copyDataBase ();
db = super.getWritableDatabase();
} catch(Exception ex)
{
ex.printStackTrace();
Log.e("Database Log", DB_PATH + " failed to copy correctly. " + ex.getLocalizedMessage());
}
}
else {
db = super.getWritableDatabase();
}
return db;
}
private void copyDataBase() throws IOException {
Log.e("copyDataBase", " called");
// Open your local db as the input stream
InputStream myInput = mContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
mDataBase=mContext.openOrCreateDatabase(DB_PATH+DB_NAME, Context.MODE_PRIVATE, null );
// 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();
//
}
// make调用你的DataBaseHelper类，如下所示： mDatabase = new DataBaseHelper（this）; mDatabase.openDataBase（）; //它将复制现有数据库，如果需要添加更多表，请在openDatabase方法中执行此操作
答案 1 :(得分：0)
只需将此行添加到您的代码中： myContext.openOrCreateDatabase（DB_PATH + DB_NAME，Context.MODE_PRIVATE，null）;
您更新的copyDataBase（）方法变为：
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;
myDataBase=myContext.openOrCreateDatabase(DB_PATH+DB_NAME, Context.MODE_PRIVATE, null );
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();
}