在项目中用SQLite数据库，数据库文件放在哪里啊？

Before trying this code, please find this line in below code:

• private static String DB_NAME ="YourDbName";// Database name
  

DB_NAME here is the name of your database. It is assumed that you have a copy of the database in the assets folder, so for example if your database name is ordersDB, then the value of DB_NAME will be ordersDB,

• private static String DB_NAME ="ordersDB";

Keep the Database in assets folder & then follow below:

DataHelper class:

• import java.io.File;
  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.SQLiteOpenHelper;
  import android.util.Log;
  
  public class DataBaseHelper extends SQLiteOpenHelper
  {
  private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window
  //destination path (location) of our database on device
  private static String DB_PATH = "";
  private static String DB_NAME ="YourDbName";// Database name
  private SQLiteDatabase mDataBase;
  private final Context mContext;
  
  public DataBaseHelper(Context context)
  {
     super(context, DB_NAME, null, 1);// 1? its Database Version
     if(android.os.Build.VERSION.SDK_INT >= 4.2){
        DB_PATH = context.getApplicationInfo().dataDir + "/databases/";        
     }
     else
     {
        DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
     }
     this.mContext = context;
  }  
  
  public void createDataBase() throws IOException
  {
     //If database not exists copy it from the assets
  
     boolean mDataBaseExist = checkDataBase();
     if(!mDataBaseExist)
     {
         this.getReadableDatabase();
         this.close();
         try
         {
             //Copy the database from assests
             copyDataBase();
             Log.e(TAG, "createDatabase database created");
         }
         catch (IOException mIOException)
         {
             throw new Error("ErrorCopyingDataBase");
         }
     }
  }
     //Check that the database exists here: /data/data/your package/databases/Da Name
     private boolean checkDataBase()
     {
         File dbFile = new File(DB_PATH + DB_NAME);
         //Log.v("dbFile", dbFile + "   "+ dbFile.exists());
         return dbFile.exists();
     }
  
     //Copy the database from assets
     private void copyDataBase() throws IOException
     {
         InputStream mInput = mContext.getAssets().open(DB_NAME);
         String outFileName = DB_PATH + DB_NAME;
         OutputStream mOutput = new FileOutputStream(outFileName);
         byte[] mBuffer = new byte[1024];
         int mLength;
         while ((mLength = mInput.read(mBuffer))>0)
         {
             mOutput.write(mBuffer, 0, mLength);
         }
         mOutput.flush();
         mOutput.close();
         mInput.close();
     }
  
     //Open the database, so we can query it
     public boolean openDataBase() throws SQLException
     {
         String mPath = DB_PATH + DB_NAME;
         //Log.v("mPath", mPath);
         mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
         //mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
         return mDataBase != null;
     }
  
     @Override
     public synchronized void close()
     {
         if(mDataBase != null)
             mDataBase.close();
         super.close();
     }
  
  }

Write a DataAdapter class like:

• import java.io.IOException;
  import android.content.Context;
  import android.database.Cursor;
  import android.database.SQLException;
  import android.database.sqlite.SQLiteDatabase;
  import android.util.Log;
  
  public class TestAdapter
  {
     protected static final String TAG = "DataAdapter";
  
     private final Context mContext;
     private SQLiteDatabase mDb;
     private DataBaseHelper mDbHelper;
  
     public TestAdapter(Context context)
     {
         this.mContext = context;
         mDbHelper = new DataBaseHelper(mContext);
     }
  
     public TestAdapter createDatabase() throws SQLException
     {
         try
         {
             mDbHelper.createDataBase();
         }
         catch (IOException mIOException)
         {
             Log.e(TAG, mIOException.toString() + "  UnableToCreateDatabase");
             throw new Error("UnableToCreateDatabase");
         }
         return this;
     }
  
     public TestAdapter open() throws SQLException
     {
         try
         {
             mDbHelper.openDataBase();
             mDbHelper.close();
             mDb = mDbHelper.getReadableDatabase();
         }
         catch (SQLException mSQLException)
         {
             Log.e(TAG, "open >>"+ mSQLException.toString());
             throw mSQLException;
         }
         return this;
     }
  
     public void close()
     {
         mDbHelper.close();
     }
  
      public Cursor getTestData()
      {
          try
          {
              String sql ="SELECt * FROM myTable";
  
              Cursor mCur = mDb.rawQuery(sql, null);
              if (mCur!=null)
              {
                 mCur.moveToNext();
              }
              return mCur;
          }
          catch (SQLException mSQLException)
          {
              Log.e(TAG, "getTestData >>"+ mSQLException.toString());
              throw mSQLException;
          }
      }
  }

Now you can use it like:

• TestAdapter mDbHelper = new TestAdapter(urContext);        
  mDbHelper.createDatabase();      
  mDbHelper.open();
  
  Cursor testdata = mDbHelper.getTestData();
  
  mDbHelper.close();

NOTE：

• For Jellybean 4.2 change:
  DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
  to:
  
  DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
  in the DataHelper class this code will work on JB 4.2 multi users.