android下的res里面数据库文件的读取问题
这是我建的一个类,作用是把res下的数据库文件读到sdcard上,可是怎么都不成功,
public class opendatabase extends Activity{
private SQLiteDatabase database=null;
public opendatabase(String DATABASE_PATH,String DATABASE_FILENAME,int id){
try
{
// 获得dictionary.db文件的绝对路径
String databaseFilename = DATABASE_PATH + "/" + DATABASE_FILENAME;
File dir = new File(DATABASE_PATH);
// 如果/sdcard/dictionary目录中存在,创建这个目录
if (!dir.exists())
dir.mkdir();
// 如果在/sdcard/dictionary目录中不存在
// dictionary.db文件,则从res\raw目录中复制这个文件到
// SD卡的目录(/sdcard/dictionary)
if (!(new File(databaseFilename)).exists())
{
// 获得封装dictionary.db文件的InputStream对象
InputStream is =getResources().openRawResource(
id);
FileOutputStream fos = new FileOutputStream(databaseFilename);
byte[] buffer = new byte[8192];
int count = 0;
// 开始复制dictionary.db文件
while ((count = is.read(buffer)) > 0)
{
fos.write(buffer, 0, count);
}
fos.close();
is.close();
}
// 打开/sdcard/dictionary目录中的dictionary.db文件
database = SQLiteDatabase.openOrCreateDatabase(
databaseFilename, null);
}
catch (Exception e)
{
}
}
public SQLiteDatabase getDatabase() {
return database;
}
public void setDatabase(SQLiteDatabase database) {
this.database = database;
}
}
下面是在activity里面调用上面函数:
public class ActivityActivity extends Activity {
private final String DATABASE_PATH2 = android.os.Environment
.getExternalStorageDirectory().getAbsolutePath()
+ "/test";
private final String DATABASE_FILENAME = "siji.db";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
opendatabase opdb=new opendatabase(DATABASE_PATH2, DATABASE_FILENAME, R.raw.siji);
SQLiteDatabase database=opdb.getDatabase();
}
}
但是如果我把上面那个类做成一个方法写到activity里面,却可以成功读取,如下
public class ActivityActivity extends Activity {
private final String DATABASE_PATH2 = android.os.Environment
.getExternalStorageDirectory().getAbsolutePath()
+ "/test";
private final String DATABASE_FILENAME = "siji.db";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
SQLiteDatabase database=openDatabase();
}
private SQLiteDatabase openDatabase()
{
try
{
// 获得dictionary.db文件的绝对路径
String databaseFilename = DATABASE_PATH2 + "/" + DATABASE_FILENAME;
File dir = new File(DATABASE_PATH2);
// 如果/sdcard/dictionary目录中存在,创建这个目录
if (!dir.exists())
dir.mkdir();
// 如果在/sdcard/dictionary目录中不存在
// dictionary.db文件,则从res\raw目录中复制这个文件到
// SD卡的目录(/sdcard/dictionary)
if (!(new File(databaseFilename)).exists())
{
// 获得封装dictionary.db文件的InputStream对象
InputStream is =getResources().openRawResource(
R.raw.siji);
FileOutputStream fos = new FileOutputStream(databaseFilename);
byte[] buffer = new byte[8192];
int count = 0;
// 开始复制dictionary.db文件
while ((count = is.read(buffer)) > 0)
{
fos.write(buffer, 0, count);
}
fos.close();
is.close();
}
// 打开/sdcard/dictionary目录中的dictionary.db文件
SQLiteDatabase database = SQLiteDatabase.openOrCreateDatabase(
databaseFilename, null);
return database;
}
catch (Exception e)
{
}
return null;
}
}
求教高手给个解释