我是Android开发的初学者，通过适当的搜索，我能够创建一个工作的sqlite数据库，但我想从资产文件夹导入预制数据库。虽然我已找到它的教程和代码，但面临我的代码中的集成问题。任何人都可以帮我提供这门课程的编码帮助： -
Wfdaadapter.java
public class Wfdaadapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_FD1 = "fd1";
public static final String KEY_FD2 = "fd2";
public static final String KEY_FD3 = "fd3";
public static final String KEY_FD4 = "fd4";
public static final String KEY_FD5 = "fd5";
private static final String TAG = "CountriesDbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
private static final String DATABASE_NAME = "iigdatabase";
private static final String SQLITE_TABLE = "iigimport";
private static final int DATABASE_VERSION = 1;
private final Context mCtx;
private static final String DATABASE_CREATE = "CREATE TABLE if not exists "
+ SQLITE_TABLE + " (" + KEY_ROWID
+ " integer PRIMARY KEY autoincrement," + KEY_FD1 + "," + KEY_FD2
+ "," + KEY_FD3 + "," + KEY_FD4 + "," + KEY_FD5 + ","
+ " UNIQUE (" + KEY_FD1 + "));";
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.w(TAG, DATABASE_CREATE);
db.execSQL(DATABASE_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS " + SQLITE_TABLE);
onCreate(db);
}
}
public Wfdaadapter(Context ctx) {
this.mCtx = ctx;
}
public Wfdaadapter open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
if (mDbHelper != null) {
mDbHelper.close();
}
}
public long createCountry(String fd1, String fd2, String fd3,
String fd4, String fd5) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_FD1, fd1);
initialValues.put(KEY_FD2, fd2);
initialValues.put(KEY_FD3, fd3);
initialValues.put(KEY_FD4, fd4);
initialValues.put(KEY_FD5, fd5);
return mDb.insert(SQLITE_TABLE, null, initialValues);
}
public boolean deleteAllCountries() {
int doneDelete = 0;
doneDelete = mDb.delete(SQLITE_TABLE, null, null);
Log.w(TAG, Integer.toString(doneDelete));
return doneDelete > 0;
}
public Cursor fetchCountriesByName(String inputText) throws SQLException {
Cursor mCursor = null;
if (inputText == null || inputText.length() == 0) {
mCursor = mDb.query(SQLITE_TABLE, new String[] { KEY_ROWID,
KEY_FD1, KEY_FD2, KEY_FD3, KEY_FD4, KEY_FD5 }, null,
null, null, null, null, null);
} else {
mCursor = mDb.query(true, SQLITE_TABLE, new String[] { KEY_ROWID,
KEY_FD1, KEY_FD2, KEY_FD3, KEY_FD4, KEY_FD5 },
KEY_FD1 + " like '%" + inputText + "%'", null, null, null,
null, null);
}
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
public Cursor fetchAllCountries() {
Cursor mCursor = mDb.query(SQLITE_TABLE, new String[] { KEY_ROWID,
KEY_FD1, KEY_FD2, KEY_FD3, KEY_FD4, KEY_FD5 }, null, null,
null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
public void insertSomeCountries() {
}
}
在app中复制资产文件夹的方法类 Wfdahelper.java
public class Wfdahelper extends SQLiteOpenHelper {
// The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.monika.sharma12/databases/";
private static String DATABASE_NAME = "iigdatabase";
private SQLiteDatabase mDb;
private final Context mCtx;
/**
* Constructor Takes and keeps a reference of the passed context in order to
* access to the application assets and resources.
*
* @param context
*/
public Wfdahelper(Context context) {
super(context, DATABASE_NAME, null, 1);
this.mCtx = 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
} 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) {
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 + DATABASE_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;
}
/**
* 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 = mCtx.getAssets().open(DATABASE_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DATABASE_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 {
// Open the database
String myPath = DB_PATH + DATABASE_NAME;
mDb = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if (mDb != null)
mDb.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
// Add your public helper methods to access and get content from the
// database.
// You could return cursors by doing "return mDb.query(....)" so it'd
// be easy
// to you to create adapters for your views.
}
答案 0 :(得分：1)
使用此
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();
}
您可以选择使用： -
AssetDatabaseOpenHelper adb = new AssetDatabaseOpenHelper(this);
SQLiteDatabase db = adb.openDatabase();
Cursor c = db.rawQuery("SELECT * FROM xxx;", null);
Log.d("MyApp", "cnt: "+c.getCount());
答案 1 :(得分：0)
在createDataBase() class
Wfdahelper方法
实施例
public Wfdahelper(Context context) {
super(context, DATABASE_NAME, null, 1);
this.mCtx = context;
createDataBase()
}