我想加载一个数据库和我的apk文件。但是，尽管将数据库添加到assets文件夹并修改了sqliteopenhelper，应用程序仍在我的手机上关闭sqliteopenhelper类
public class openingclass extends SQLiteOpenHelper
{
public openingclass(Context c) {
super(c,Db_NAME, null, DB_VERSION);
}
public void createDataBase() {
boolean dbExist;
try {
dbExist = checkDataBase();
} catch (SQLiteException e) {
e.printStackTrace();
throw new Error("database dose not exist");
}
if(dbExist){
//do nothing - database already exist
}else{
try {
copyDataBase();
} catch (IOException e) {
e.printStackTrace();
throw new Error("Error copying database");
}
//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();
}
}
/**
* 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_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
throw new Error("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{
//copyDataBase();
//Open your local db as the input stream
InputStream myInput = c1.getAssets().open(Db_NAME);
// Path to the just created empty db
String outFileName = DB_PATH +"/"+ Db_NAME;
File databaseFile = new File(DB_PATH);
// check if databases folder exists, if not create one and its subfolders
if (!databaseFile.exists()){
databaseFile.mkdir();
}
//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 synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase arg0) {
String S = "create table " +
TABLE_NAME +
" (" +
TABLE_COL_MAIL + " text primary key," +
TABLE_COL_NAME + " text," +
TABLE_COL_PASS + " text," +
TABLE_COL_PHO + " text," +
TABLE_COL_ADD + " text," +
TABLE_COL_GEN + " text," +
TABLE_COL_DOB + " text" +
");";
arg0.execSQL(S);
String S1 = "create table " +
SECOND_TABLE_NAME +
" (" +
TABLE_COL_USER + " text," +
TABLE_COL_PRODUCT + " text," +
TABLE_COL_QUANTITY + " integer" +
");";
arg0.execSQL(S1);
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
}
此外，我还添加了两个变量作为
private final String DB_PATH="data/data/com.example.shopkart/databases/";
private final String Db_NAME = "dbshopkart.db";
如果它在Emulator上运行，那么您的代码很可能很好。因此，设备的内部数据肯定有问题。在数据库中进行这些更改之前，您的手机上是否已经安装了该应用程序？如果是，则卸载该应用程序并再次运行。我认为它在你的模拟器上工作，因为模拟器每次都会创建一个新的AVD，所以没有现有的数据。请尝试从设备上卸载，然后重新运行。