我有一个sqlite数据库存储在assets文件夹中。虽然我从assest文件夹复制数据库但它没有复制数据库。大小总是0bytes。
这是我的DBhelper
public class DBhelper extends SQLiteOpenHelper {
private static String DB_NAME = "channels";
private SQLiteDatabase myDataBase;
private DBhelper db;
public Context myContext;
File dbFile;
File dbFilePath;
Cursor ch;
public DBhelper(Context myContext) {
super(myContext, DB_NAME, null, 1);
this.myContext = myContext;
System.out.println("Context value from database helper:--"+myContext);
String state=Environment.getExternalStorageState();
System.out.println("My Storage State:-"+state);
}
public void createDataBase(Context mycontext) throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
System.out.println("Yes Database Exists");
String path = dbFile.getAbsolutePath();
System.out.println("My database Path:--"+path);
}
if(!dbExist)
{
//System.out.println("No Databse Exists so we created Directory:-"+flag);
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
public boolean checkDataBase() {
dbFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"channels");
return dbFile.exists();
}
/*public boolean checkDataBase()
{
dbFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"photodb");
return dbFile.exists();
}*/
private void copyDataBase() throws IOException{
dbFile= new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"NewsFeed");
boolean flag=dbFile.mkdir();
dbFilePath = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"NewsFeed"+"/"+"channels");
dbFilePath.createNewFile();
InputStream myInput = myContext.getAssets().open("channels");
String outFileName = dbFilePath.getAbsolutePath();
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
System.out.println("Database copy");
}
public void preservedata() throws IOException{
InputStream myInput = new FileInputStream(Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"NewsFeed"+"/"+"channels") ;
//myContext.getAssets().open("photodb");
String outFileName = dbFilePath.getAbsolutePath();
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException{
String myPath = Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"NewsFeed"+"/"+"channels" ;
System.out.println("MY DATABASE PATH:----"+myPath);
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
我从getView方法的listviewadapter类调用数据库
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
final ViewHolder vh;
// View v = view;
System.out.println("My Context Value from India List :-"+context);
if (view == null) {
vh= new ViewHolder();
LayoutInflater vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = vi.inflate(R.layout.newschannelrow, null,false);
// LayoutInflater vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
// v = vi.inflate(R.layout.newschannelrow, null);
// vh.textview = new TextView(mycontext);
vh.ivNewsChanIcon = (ImageView)view.findViewById(R.id.ivNewsChanIcon);
vh.tvNameOfChannel = (TextView)view.findViewById(R.id.tvNameOfChannel);
vh.tvNewsFeedLink = (TextView)view.findViewById(R.id.tvNewsFeedLink);
vh.tvNewsFav = (CheckBox)view.findViewById(R.id.tvNameofChannelFav);
vh.tvNewsFav.setTag(i);
view.setTag(vh);
}
else
{
vh = (ViewHolder) view.getTag();
}
NewsFeedLink nfl = data.get(i);
String name = nfl.getChannelName();
String link = nfl.getFeedLink();
vh.tvNameOfChannel.setText(name);
vh.tvNewsFeedLink.setText(link);
//ImageView imageView = new ImageView(mycontext);
// vh.imageView.setImageResource(ImageIds[position]);
// vh.imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
// vh.textview.setText(Imagename[position]);
//imageView.setLayoutParams(new GridView.LayoutParams(100, 100));
vh.tvNewsFav.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// TODO Auto-generated method stub
if(isChecked==false){
System.out.println("This "+(Integer)buttonView.getTag()+" CheckBox Is un-Clicked");
}
if(isChecked==true){
System.out.println("I am from onCheck Changed in India List context value:-"+context);
mydb = new DBhelper(context);
try {
mydb.createDataBase(context);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
mydb.openDataBase();
System.out.println("This "+(Integer)buttonView.getTag()+" CheckBox Is Clicked");
mydb.add((vh.tvNameOfChannel).getText().toString(), (vh.tvNewsFeedLink).getText().toString());
try {
mydb.preservedata();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mydb.close();
}
}
});
return view;
}
请帮助这方面..
答案 0 :(得分：0)
试试此代码
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.Toast;
public class SqliteAdapter_InsideDB extends SQLiteOpenHelper {
private static String DB_PATH = "your path where you need to copy DB ";
private static String DB_NAME = "your.db";
private SQLiteDatabase database;
private final Context myContext;
public SqliteAdapter_InsideDB(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
try {
createDataBase();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
Log.e("DB-Exception", e.toString());
}
}
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
openDataBase();
} else {
this.getReadableDatabase();
try {
copyDataBase();
openDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
} catch (SQLiteException e) {
}
return checkDB != null ? true : false;
}
private void copyDataBase() throws IOException {
InputStream myInput = myContext.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
String myPath = DB_PATH + DB_NAME;
database = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if (database != null)
database.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public boolean isOpen() {
if (database != null) {
return database.isOpen();
}
return false;
}
public Cursor executeSQLQuery(String sql, String[] selectionArgs) {
Cursor cursor = null;
try {
if (database != null) {
cursor = database.rawQuery(sql, selectionArgs);
}
} catch (SQLiteException sqle) {
Toast.makeText(this.myContext,
"Unable to execute sql query \n" + sqle.getMessage(),
Toast.LENGTH_SHORT).show();
}
return cursor;
}
public int getRow(String scanCodeNo) {
int count;
count = database
.query("table_name", null,
"column_name" + " = '" + value + "'", null, null,
null, null).getCount();
database.close();
return count;
}
}
不要忘记在清单
中添加权限 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />