从Android的内存读取SQLite数据库(Reading SQLITE database fro

I have created an sqlite database on a Java application and have pushed it to my android. I want to read this database (probably write into it later too). Most of the tutorials I have found so far create the DB within the android...

I don't think I need to override the onCreate() and onUpdate() methods of SQLiteOpenHelper class do I ? Also the part that in the below tutorial he has created the tables, since I already have my database

Any tutorial, sample code u guys might know of ?

public class DatabaseHandler extends SQLiteOpenHelper {

    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "contactsManager";

    // Contacts table name
    private static final String TABLE_CONTACTS = "contacts";

    // Contacts Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_PH_NO = "phone_number";

    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
                + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
                + KEY_PH_NO + " TEXT" + ")";
        db.execSQL(CREATE_CONTACTS_TABLE);
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);

        // Create tables again
        onCreate(db);
    }

I Simply need to open the DB I have in the memory, execute an sql query agianst my DB and get the result.

Answer 1:

您必须在设备上拷贝，从资产到您的应用程序存储区中的DB（或其他可访问的位置），然后才能使用它。 你不能直接使用它了.apk文件中。

如何去了解它的一个例子：

public class DBAdapter { 

// DB info 
public static final String MAIN_DATABASE_NAME = "yourDB"; 
public static String MAIN_DB_PATH = "/data/data/your.package.name/databases/"; 
public static final int MAIN_DATABASE_VERSION = 1; 

// database control 
private DatabaseHelper mDbHelper; 
private static SQLiteDatabase mDb; 
private static Context mCtx; 

private static class DatabaseHelper extends SQLiteOpenHelper { 
    DatabaseHelper(Context context, String dbname, int dbversion) { 
        super(context, dbname, null, dbversion); 
        if (checkDataBase(dbname)) { 
            openDataBase(dbname); 
        } else { 
            try { 
                this.getReadableDatabase(); 
                copyDataBase(dbname); 
                this.close(); 
                openDataBase(dbname); 
            } catch (IOException e) { 
                throw new Error("Error copying database"); 
            } 
            Toast.makeText(context, 
                    "Initial " + dbname + " database has been created", 
                    Toast.LENGTH_LONG).show(); 
        } 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    } 
} 

public DBAdapter(Context ctx) { 
    DBAdapter.mCtx = ctx; 
} 

public DBAdapter open(String dbname, int dbversion) throws SQLException { 
    mDbHelper = new DatabaseHelper(mCtx, dbname, dbversion); 
    mDb = mDbHelper.getWritableDatabase(); 
    return this; 
} 

public void close() { 
    mDbHelper.close(); 
} 

private static void copyDataBase(String dbname) throws IOException { 
    InputStream myInput = mCtx.getAssets().open(dbname); 
    String outFileName = MAIN_DB_PATH + dbname; 
    OutputStream myOutput = new FileOutputStream(outFileName); 
    byte[] buffer = new byte[1024]; 
    int length; 
    while ((length = myInput.read(buffer)) > 0) { 
        myOutput.write(buffer, 0, length); 
    } 
    myOutput.flush(); 
    myOutput.close(); 
    myInput.close(); 
} 

private static boolean checkDataBase(String dbname) { 
    SQLiteDatabase checkDB = null; 
    boolean exist = false; 
    try { 
        String db = MAIN_DB_PATH + dbname; 
        checkDB = SQLiteDatabase.openDatabase(db, null, 
                SQLiteDatabase.OPEN_READONLY); 
    } catch (SQLiteException e) { 
        Log.v("db log", "database does't exist"); 
    } 
    if (checkDB != null) { 
        exist = true; 
        checkDB.close(); 
    } 
    return exist; 
} 

private static void openDataBase(String dbname) throws SQLException { 
    String dbPath = MAIN_DB_PATH + dbname; 
    mDb = SQLiteDatabase.openDatabase(dbPath, null, 
            SQLiteDatabase.OPEN_READWRITE); 
} 
} 

文章来源: Reading SQLITE database from Android memory