对于我的应用程序,我已经有一个现成的数据库(即它存储在名为example.sqlite的assets文件夹中,并且值已插入其中。)
这是我的类数据库助手::
package com.huskerit.util;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import android.content.ContentValues;
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 com.huskerit.model.AllSportData;
public class DatabaseHelper extends SQLiteOpenHelper {
//private static final int DATABASE_VERSION = 1;
// Table name
public static final String TABLE = "all_team";
public static final String TABLE_SELECTED = "selected_team";
// Columns
public static final String ID = "id";
public static final String NAME = "name";
public static final String CATEGORY1 = "category1";
public static final String CATEGORY2 = "category2";
public static SQLiteDatabase database;
private final Context myContext;
public DatabaseHelper(Context context)
{
super(context, Constant.DB_NAME, null, 1);
this.myContext = context;
}
public void onCreate(SQLiteDatabase db)
{
}
public void createDataBase() throws IOException
{
boolean dbExist = checkDataBase();
System.out.println("~~~~~~~~"+dbExist);
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.
DatabaseHelper.this.getReadableDatabase();
try
{
this.close();
copyDataBase();
}
catch (Exception e)
{
e.printStackTrace();
System.out.println(e.getMessage());
}
}
}
/**
* 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 = Constant.DB_PATH + Constant.DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
catch(SQLiteException e)
{
//database does't exist yet.
e.printStackTrace();
}
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
// Path to the just created empty db
String outFileName = Constant.DB_PATH + Constant.DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
InputStream myInput = myContext.getAssets().open(Constant.DB_NAME);
//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);
}
myInput.close();
//Close the streams
myOutput.flush();
myOutput.close();
}
public void openDataBase() throws SQLException
{
//Open the database
String myPath = Constant.DB_PATH + Constant.DB_NAME;
database = SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READWRITE);
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
}
}
现在我在我的活动中调用数据库,如::
public class TeamSelectActivity extends Activity
{
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_teamselect);
if(Constant.mDatabase == null)
{
Constant.mDatabase = new DatabaseHelper(TeamSelectActivity.this);
}
try
{
//Constant.mDatabase.createDataBase(); //DataBase();
Constant.mDatabase.openDataBase();
}
catch (SQLException e)
{
e.printStackTrace();
}
}
}
这是我的日志跟踪::
I/Database(13203): sqlite returned: error code = 14, msg = cannot open file at source line 25467
E/Database(13203): sqlite3_open_v2("/data/data/com.huskerit.login/databases/wimbim.sqlite", &handle, 2, NULL) failed
W/System.err(13203): android.database.sqlite.SQLiteException: unable to open database file
at android.database.sqlite.SQLiteDatabase.dbopen(Native Method)
at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1849)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:820)
at com.huskerit.util.DatabaseHelper.openDataBase(DatabaseHelper.java:130)
at com.huskerit.login.TeamSelectActivity.onCreate(TeamSelectActivity.java:93)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
at android.app.ActivityThread.access$1500(ActivityThread.java:117)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:3687)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:842)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
我无法弄明白我做错了什么.. 任何帮助将不胜感激..
提前致谢...
答案 0 :(得分:1)
这是由于checkDataBase()方法造成的。 使用以下内容检查数据
private boolean checkDataBase() {
// TODO Auto-generated method stub
File dbFile = new File(DB_PATH + DB_NAME);
return dbFile.exists();
}