我不明白为什么我无法将我的db文件(abic_)复制到应用程序目录("/ data/data /"+ context.getPackageName()+"/ databases")
这是我的DataBaseHelper类:
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.IOException;import java.io.OutputStream;
import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
public class DataBaseHelper extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private String DB_PATH;
private static String DB_NAME = "abic_";
private static final Integer DB_VERSION = 1;
private SQLiteDatabase mydb;
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 DataBaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
this.myContext = context;
DB_PATH = "/data/data/" + context.getPackageName() + "/databases";
}
@Override
public void onCreate(SQLiteDatabase db) {;
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void apriDatabase() throws SQLException {
try {
String percorso = DB_PATH + DB_NAME;
mydb = SQLiteDatabase.openDatabase(percorso, null, SQLiteDatabase.OPEN_READONLY);
} catch (Exception e) {
e.printStackTrace();
}
}
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) {
e.printStackTrace();
}
}
}
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;
// if the path doesn't exist first, create it
File f = new File(outFileName);
if (!f.exists()){
f.mkdir();
f.createNewFile();
}
//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();
}
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;
}
@Override
public synchronized void close() {
if(mydb != null)
mydb.close();
super.close();
}
}这是使用此类的listview:
import android.app.ListActivity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
public class abicabList extends ListActivity {
protected EditText searchText;
protected SQLiteDatabase mydb;
protected Cursor cursor;
protected ListAdapter adapter;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mydb = (new DataBaseHelper(this)).getWritableDatabase();
searchText = (EditText) findViewById (R.id.searchText);
}
public void search(View view) {
String text = searchText.getText().toString();
String cap = "CAP";
// || is the concatenation operation in SQLite
if (text.length()14) {
cursor = mydb.rawQuery("SELECT _id, ABI, BANCA, CAB, CAP, Filiale, City FROM abicab WHERE ABI || CAB LIKE ? LIMIT 30",
new String[]{"%" + searchText.getText().toString().substring(6,10) + "%" + searchText.getText().toString().substring(11,15) + "%"});
adapter = new SimpleCursorAdapter(
this,
R.layout.abicab_list_item,
cursor,
new String[] {"BANCA", "Filiale", "City", "CAP"},
new int[] {R.id.BANCA, R.id.Filiale, R.id.City ,R.id.CAP});
setListAdapter(adapter);
}
} 因此,当我运行应用程序时,db在文件夹中创建,但它不包含我在资产文件夹中的数据库中的表(参见图片[1]:http://i.stack.imgur.com /AaFj8.jpg).在此先感谢您的帮助.
我已经解决了这个问题。
\n\n1）我使用了Almanac 0.0.17（开源项目）中使用的类AlmanacSQLiteDatabaseAdapter.java，您可以在这里找到： \n link。您可以满足您的需求（在我的例子中，我已重命名为DatabaseHelper）；
\n\n2）这是使用Helper的类（它是一个列表视图，在EditText中执行sql rawquery读取字符串 - 这是本教程“coenraets.org/blog/android-samples/androidtutorial/”的安排：
\n\n
public class MiaList extends Activity { \n\n protected EditText searchText; \n protected SQLiteDatabase db; \n protected Cursor cursor; \n protected ListAdapter ladapter; \n protected ListView miaList; \n private static final String DATABASE_NAME = "miodb.jpg";\n/*\nL\'ESTENSIONE JPG (o mp3, mov) questo perch\xc3\xa8 android ha il limite di 1 mb per i file di testo \no simili nella asset, mentre NON HA limiti per i file multimediali! Nel mio caso si tratta di 4mb\n*/\n\n /** Called when the activity is first created. */ \n @Override \n public void onCreate(Bundle savedInstanceState) { \n super.onCreate(savedInstanceState); \n setContentView(R.layout.main); \n\n//qui sotto richiamo la classe DatabaseHelper\n\n DatabaseHelper dbAdapter = DatabaseHelper.getInstance(this, DATABASE_NAME);\n /*note di Vytek*/\n // OK Dovrei usare aSQLiteDatabaseAdapter.getDatabase(); ma questo crea\n // problemi nella fase di OnPause quando premo Back cosi\' invece non\n // ottengo errori\n // e viene fatta la normale copia del DB (13/8/2010 23.18)\n // db = aSQLiteDatabaseAdapter.getWritableDatabase();\n // Per ovviare a questo problema controllo se e\' la prima volta che\n // chiamo applicazione\n if (getFirstRun()) {\n db = dbAdapter.getDatabase();\n setRunned();\n } else {\n db = dbAdapter.getWritableDatabase();\n }\n\n searchText = (EditText) findViewById (R.id.searchText); \n miaList = (ListView) findViewById (R.id.list); \n } \n\n\n private void setRunned() {\n // TODO Auto-generated method stub\n\n }\n\n private boolean getFirstRun() {\n // TODO Auto-generated method stub\n return false;\n }\n\n public void search(View view) { \n\n String text = searchText.getText().toString();\n // || \xc3\xa8 l\'operatore "concatena" in SQLite \n if (text.length()<15){\n cursor = db.rawQuery("SELECT *FROM miatable WHERE AAA || \' \' || BBB || \' \' || CCC LIKE ? LIMIT 30", \n new String[]{"%" + searchText.getText().toString() + "%"}); \n ladapter = new SimpleCursorAdapter( \n this, \n R.layout.mialist_list_item, \n cursor, \n new String[] {"_id", "AAA", "BBB", "CCC"}, \n new int[] {R.id._id, R.id.AAA, R.id.BBB, R.id.CCC}); \n miaList.setAdapter(ladapter); \n //istruzione da eseguire\n }\n else { \n cursor = db.rawQuery("SELECT * FROM miatable WHERE AAA || BBB LIKE ? LIMIT 30", \n new String[]{"%" + searchText.getText().toString().substring(6,10) + "%" + searchText.getText().toString().substring(11,15) + "%"}); \n ladapter = new SimpleCursorAdapter( \n this, \n R.layout.mialist_list_item, \n cursor, \n new String[] {"_id", "AAA", "BBB", "CCC"}, \n new int[] {R.id._id, R.id.AAA, R.id.BBB, R.id.CCC}); \n miaList.setAdapter(ladapter); \n //istruzione da eseguire\n } \n\n\n }\n\n}\n当然，SQLite DB“miodb.jpg”必须位于 eclipse 工作区的 asset 文件夹中。
\n\nPS \n我对 db 使用了 jpg 扩展名，因为 asset 文件夹对 db 或 txt 或 xml 扩展名有 1Mb 的限制。
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