我陷入了令人沮丧的境地。我有一个SQlite数据库类如下：
// The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.example.ABC/databases/";
private static String DB_NAME = "ABCdb.sqlite";
private SQLiteDatabase myDataBase;
private static int DATABASE_VERSION=2;
private final Context myContext;
/**
* Constructor Takes and keeps a reference of the passed context in order to
* access to the application assets and resources.
*
* @param context
*/
public DBHelper(Context context) {
super(context, DB_NAME, null, DATABASE_VERSION);
this.myContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own
* database.
* */
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
// do nothing - database already exist
// By calling this method here onUpgrade will be called on a
// writable database, but only if the version number has been increased
this.getWritableDatabase();
} else {
// 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();
try {
copyDataBase();
} catch (IOException e) {
System.out.println(e.toString());
// throw new Error("Error copying database");
}
}
}
/**
* 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_READWRITE);
} catch (SQLiteException e) {
// 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 {
// 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 SQLiteDatabase openDataBase() throws SQLException {
// Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.NO_LOCALIZED_COLLATORS);
return myDataBase;
}
@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) {
System.out.println("NewVersion : "+newVersion+", OldVersion : "+oldVersion);
if(newVersion>oldVersion){
myContext.deleteDatabase(DB_NAME);
try {
copyDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
}
// Add your public helper methods to access and get content from the
// database.
// You could return cursors by doing "return myDataBase.query(....)" so it'd
// be easy
// to you to create adapters for your views.
}
Play商店上传的app已将DATABASE_VERSION设置为1.我在DB中添加了一些新表。我将DATABASE_VERSION增加到2.但是当我使用debug keystore运行应用程序时，调用onUpgrade（）方法并调用DB正在升级但是当我签署应用程序然后更新已安装的应用程序时，它不会升级数据库。我不知道我是否遗漏了什么。任何帮助都非常感谢。
答案 0 :(得分：2)
您应该只能使用应用的其他调试版升级应用的调试版本。发布版本也是如此。发行版只能使用其他发行版升级。换句话说 - 如果您使用已使用相同密钥签名的应用程序替换应用程序，则只是升级。
因此，根据您的描述（使用发布版本时无法升级数据库），听起来好像您已将调试版本替换为发行版本。 Android会将此方案识别为相同的应用程序，但它将首先取消安装初始版本（调试），然后将其替换为新版本（发布）。因此，虽然它可能在用户看来是升级，但这实际上是一种卸载/安装方案。
据我所知，这是解释你所见所闻的唯一方法。