从包中嵌入的sqlite中获取数据

Question

我尝试从 Sqlite浏览器中读取数据库中的数据。一切都好，但我看不到结果。我将mydb.db复制到我在项目根目录中创建的assets文件夹中。

我的问题在哪里？

感谢。

public class DatabasesActivity extends Activity {
  Cursor c;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_databases);

    DBAdapter db = new DBAdapter(this);
    try {
      String destPath = "/data/data/"+getPackageName()+"/databases";
      File f=new File(destPath);
      if (!f.exists()) {
        f.mkdirs();
        f.createNewFile();
        CopyDB(getBaseContext().getAssets().open("mydb"),
        new FileOutputStream(destPath+"/MyDB"));
      }
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    db.open();

    Cursor c=db.getAllContacts();//.getAllContacts();
    if(c.moveToFirst()) {
      do {
        DisplayContact(c);
      } while (c.moveToNext());
    }
   db.close();
  }

  public void CopyDB(InputStream inputStream,
                   OutputStream outputStream) throws IOException {
    byte[] buffer=new byte[1024];
    int lenght;
    while ((lenght=inputStream.read(buffer))>0) {
      outputStream.write(buffer,0,lenght);
      Toast.makeText(this,"copy", Toast.LENGTH_LONG).show();
    }
    inputStream.close();
    outputStream.close();
  }

  public void DisplayContact(Cursor c) {
    Toast.makeText(this,"Name: "+c.getString(1)+"\n"+
                        "Date: "+c.getString(2)+"\n"+
    "Email:                ",
            Toast.LENGTH_LONG).show();
  } 
}

这是我的 DBAdapter ：

public class DBAdapter {

  private static final String TAG = "DBAdapter"; //used for logging database version changes

  // Field Names:
  public static final String KEY_ROWID = "_id";
  public static final String KEY_NAME = "name";
  public static final String KEY_EMAIL = "email";

  public static final String[] ALL_KEYS = new String[] {KEY_ROWID, KEY_NAME, KEY_EMAIL};

  // Column Numbers for each Field Name:
  public static final int COL_ROWID = 0;
  public static final int COL_TASK = 1;
  public static final int COL_DATE = 2;

  // DataBase info:
  public static final String DATABASE_NAME = "MyDB";
  public static final String DATABASE_TABLE = "contacts";
  public static final int DATABASE_VERSION = 1; // The version number must be incremented each time a change to DB structure occurs.

  //SQL statement to create database
  private static final String DATABASE_CREATE_SQL =
        "CREATE TABLE " + DATABASE_TABLE
                + " (" + KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
                + KEY_NAME + " TEXT NOT NULL, "
                + KEY_EMAIL + " TEXT"
                + ");";

  private final Context context;
  private DataBaseHelper DBHelper;
  private SQLiteDatabase db;

  public DBAdapter(Context ctx) {
    this.context = ctx;
    DBHelper = new DataBaseHelper(context);
  }

  private static class DataBaseHelper extends SQLiteOpenHelper {
    DataBaseHelper(Context context) {
      super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    public void onCreate(SQLiteDatabase db) {
      try {
        db.execSQL(DATABASE_CREATE_SQL);
      } catch (SQLException e) {
        e.printStackTrace();
      }
    }

    public void onUpgrade(SQLiteDatabase _db, int oldVersion, int newVersion) {
      Log.w(TAG, "Upgrading application's database from version " + oldVersion
                + " to " + newVersion + ", which will destroy all old data!");
    }
  }

  // Open the database connection.
  public DBAdapter open() throws SQLException {
    db = DBHelper.getWritableDatabase();
    return this;
  }

  // Close the database connection.
  public void close() {
    DBHelper.close();
  }

  // Add a new set of values to be inserted into the database.
  public long insertContact(String name, String email) {
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_NAME, name);
    initialValues.put(KEY_EMAIL, email);
    return db.insert(DATABASE_TABLE,null,initialValues);

    // Insert the data into the database.
  }

  // Delete a row from the database, by rowId (primary key)
  public boolean deleteContact(long rowId) {
    String where = KEY_ROWID + "=" + rowId;
    return db.delete(DATABASE_TABLE, where, null) > 0;
  }

  public Cursor getAllContacts() {
    String where = null;
    Cursor c =  db.query(true, DATABASE_TABLE, ALL_KEYS, where, null, null, null, null, null);
    if (c != null) {
      c.moveToFirst();
    }
    return c;
  }

  /*public void deleteAll() {
    Cursor c = getAllRows();
    long rowId = c.getColumnIndexOrThrow(KEY_ROWID);
    if (c.moveToFirst()) {
        do {
            deleteRow(c.getLong((int) rowId));
        } while (c.moveToNext());
    }
    c.close();
  }*/

  // Return all data in the database.

  // Get a specific row (by rowId)
  public Cursor getContacts(long rowId) throws SQLException {
    String where = KEY_ROWID + "=" + rowId;
    Cursor c =  db.query(true, DATABASE_TABLE, ALL_KEYS,
            where, null, null, null, null, null);
    if (c != null) {
      c.moveToFirst();
    }
    return c;
  }

  // Change an existing row to be equal to new data.
  public boolean updateRow(long rowId, String name, String email) {
    String where = KEY_ROWID + "=" + rowId;
    ContentValues newValues = new ContentValues();
    newValues.put(KEY_NAME, name);
    newValues.put(KEY_EMAIL, email);
    // Insert it into the database.
    return db.update(DATABASE_TABLE, newValues, where, null) != 0;
  }
}

这是我的 Sqlite浏览器屏幕截图：

Answer 1

作为@CL。说，你应该使用SQLiteAssetHelper。

如果您使用基于Gradle的IDE，例如Android Studio，只需在 app build.gradle 文件中添加以下依赖项：

compile 'com.readystatesoftware.sqliteasset:sqliteassethelper:+' 

如果您使用Eclipse，请下载最新的库JAR并将其放入项目的libs文件夹中。从this JAR link下载。

添加库后，通过在 DatabaseHelper 中更改以下代码来扩展 DatabaseHelper SQLiteAssetHelper ：

private static class DataBaseHelper extends SQLiteOpenHelper 

为：

private static class DataBaseHelper extends SQLiteAssetHelper

然后将您的数据库添加到资产文件夹，记得首先压缩或gzip，它位于数据库文件夹中，如：

assets/databases/mydb.db.zip

请在SQLiteAssetHelper github link

了解详情