請試試這個代碼... 這是我使用和正常工作。
只需替換DB_NAME，DATABASE_NAME和DB_PATH變量即可。
package your.packagename;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
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;
import android.util.Log;
public class database extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private static String DB_PATH = "/data`/data/com.example.applicationame/databases/";`
// Database Name
private static String DB_NAME = "DB.sqlite";
// Logcat tag
private static final String LOG = "database";
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "DB.sqlite";
// Table Names
private static final String TABLE_COUNTIES = "Counties";
private static final String TABLE_DESCRIPTIONS = "Descriptions";
private static final String TABLE_NEIGHBORHOODS = "Neighborhoods";
// Common column names
private static final String KEY_ID = "_id";
// TABLE_COUNTIES Table - column names
private static final String COL_COUNTYDETAIL = "countyDetail";
// TABLE_DESCRIPTIONS Table - column names
private static final String COL_DESCRIPTIONDETAIL = "descriptionDetail";
// TABLE_NEIGHBORHOODS Table - column names
private static final String COL_NEIGHBORHOODDETAIL = "neighborhoodDetail";
private SQLiteDatabase myDataBase;
private final Context myContext;
public static long INSERT_ERROR = -1;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public database(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.myContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException{
Log.d(LOG, "Calling checkDataBase() Method");
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
Log.d(LOG, "!!!Database Found!!!");
}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.
Log.d(LOG, "!!!Creating Empy Database!!!");
this.getReadableDatabase();
this.close();
try {
Log.d(LOG, "!!!Coping Database!!!");
copyDataBase();
} catch (IOException e) {
throw new Error(e);
}
}
}
/**
* 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 + DB_NAME;
Log.d(LOG, "looking database at " + myPath);
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
Log.e(LOG, "Exception: 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 = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
Log.d(LOG, "Coping database from " + myInput + ", to " + outFileName);
//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{
openDataBase(true);
}
public void openDataBase(boolean readonly) throws SQLException{
//Open the database
String myPath = DB_PATH + DB_NAME;
if (readonly)
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
else
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) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
我希望它有幫助。 好運
是'c.getPackageName（）'返回你期望的？ – Prudhvi 2015-02-09 01:02:49
是@prudhvi，我也試過明確寫包名，但結果是一樣的。事實上，如果你看看控制檯消息，它說錯誤在FileOutPutStream中，而不是InputStream – Michele 2015-02-09 01:07:50
我所假設的是，你的文件不存在，所以你的'if'條件評估爲真。檢查該路徑中是否有該文件。 – Prudhvi 2015-02-09 01:21:26