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我正在尝试将我的数据库从版本 1 升级到版本 2。我正在分配DATABASE_VERSION = 2（也分配了第一个版本）但onUpgrade从未调用过。可能代码中存在明显错误，但我看不到它，因为我试图解决这个问题很长时间。

这是数据库助手类的代码：

public class DatabaseHelper extends SQLiteOpenHelper {

    private static final int DATABASE_VERSION = 2;
    public static String DB_PATH;
    public static String DB_NAME = "db.sqlite3";
    public SQLiteDatabase database;
    public final Context context;

    public DatabaseHelper(Context context) {
        super(context, DB_NAME, null, DATABASE_VERSION);
        this.context = context;

        File direct = new File(Environment.getExternalStorageDirectory()
                + "/.test");
        if (!direct.exists()) {
            if (direct.mkdir())
                ;
        }
        DB_PATH = Environment.getExternalStorageDirectory().getPath()
                + "/.test/";
    }

    public void createDataBase() {
        boolean dbExist = checkDataBase();
        if (!dbExist) {
            try {
                copyDataBase();
            } catch (IOException e) {
                Log.e(this.getClass().toString(), "Copying error");
                throw new Error("Error copying database!");
            }
        }
    }

    private boolean checkDataBase() {
        SQLiteDatabase checkDb = null;
        try {
            String path = DB_PATH + DB_NAME;
            checkDb = SQLiteDatabase.openDatabase(path, null,
                    SQLiteDatabase.OPEN_READONLY);
        } catch (SQLException e) {
            Log.e(this.getClass().toString(), "Error while checking db");
        }
        if (checkDb != null) {
            checkDb.close();
        }
        return checkDb != null;
    }

    private void copyDataBase() throws IOException {
        InputStream externalDbStream = context.getAssets().open(
                "databases/" + DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        OutputStream localDbStream = new FileOutputStream(outFileName);

        byte[] buffer = new byte[1024];
        int bytesRead;
        while ((bytesRead = externalDbStream.read(buffer)) > 0) {
            localDbStream.write(buffer, 0, bytesRead);
        }
        localDbStream.close();
        externalDbStream.close();
    }

    public SQLiteDatabase openDataBase() throws SQLException {
        String path = DB_PATH + DB_NAME;
        if (database == null) {
            createDataBase();
            database = SQLiteDatabase.openDatabase(path, null,
                    SQLiteDatabase.OPEN_READONLY);
        }
        return database;
    }

    // some unimportant methods

@Override
    public void onCreate(SQLiteDatabase db) {
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.w("myLogs", " --- onUpgrade database --- ");
    }

在活动中，我这样调用数据库：

DatabaseHelper dbOpenHelper = new DatabaseHelper(this);
SQLiteDatabase database = dbOpenHelper.openDataBase();

我的错误在哪里？请帮忙。

UPD： database.getVersion()返回 0

更新openDataBase()的方法（它的工作）：

public SQLiteDatabase openDataBase() throws SQLException {
    String path = DB_PATH + DB_NAME;
    if (database == null) {
        createDataBase();
        database = SQLiteDatabase.openDatabase(path, null,
            SQLiteDatabase.OPEN_READWRITE);
        this.getWritableDatabase();
    }
    return database;
}
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1 回答 1

3

本地数据库版本将始终为 0 并且onUpgrade不会被调用，因为您从未调用过getWritableDatabase/getReadableDatabase，这将碰撞版本并返回本地数据库。

所以你需要：

  1. getReadableDatabase();在你的constructor/oncreate中调用，只是为了触发进程，以防数据库版本被改变
    或
  2. 手动检查 sdcard 版本，db.getVersion();与当前版本进行比较 - DATABASE_VERSION. 做任何你需要做的事情——升级或降级。
于 2013-01-15T07:14:11.520 回答