我不明白为什么我无法将数据库文件（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();
}
}
这是使用此类的列表视图：
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，会在文件夹中创建数据库，但它不包含资产文件夹中的数据库中的表（参见图片 [1]：https://i.stack.imgur.com/AaFj8.jpg https://i.stack.imgur.com/AaFj8.jpg）。
在此先感谢您的帮助。
