Question

我想使用预加载的数据库。数据库必须附在应用程序中，然后才能更新。我对如何连接以避免问题有很多疑问。我问那些处理问题的专业人士。谢谢。

如果我的基数大于1 MB，则会弹出错误D / asset（909）：数据超过UNCOMPRESS_DATA_MAX。可以分解为小于1兆字节的片段，并且可以更改为增加（“。jpg”，“。Jpeg”，“。Png”，“。Gif”，“。wav”，“。mp2”，“。 mp3“，”。ogg“，”。aac“，”。mpg“，”。mpeg“，”。mid“，”。midi“，”。smf“，”。jet“，”。rtttl“，”。 imy“，”。xmf“，”。mp4“，”。m4a“，”。m4v“，”。3 gp“，”。3 gpp“，”。3 g2“，”。3 gpp2“，”。amr “，”。awb“，”。wma“，”。wmv“）。哪个选项更好（更容易 - 更改扩展名）。
可能会失败“没有这样的表android_metadata”但是我手动添加到数据库en_US，但是如果应用程序多语言呢？
在读取数据库时，我使用的方法是mDb = getReadableDatabase（）;,但是我正处于近距离阅读的末尾 - mDb.close（）;正如他们在互联网上所说，可能无关心任何错误无法打开数据库文件。这尤其适用于HTC设备。

以下引用代码

public class QuestionsDbAdapter extends SQLiteOpenHelper {

private String DATABASE_PATH = "/data/data/YOUR_PACKAGE/";
public static final String DATABASE_NAME = "mantestQuestions";

public static final String TABLE_QUESTIONS = "Questions";
public static final String QUESTIONS_COLUMN_ID = "_id";
public static final String QUESTIONS_COLUMN_QUESTION ="Question";

public static final String TABLE_ANSWERS = "Answers";
public static final String ANSWERS_COLUMN_ID = "_id";
public static final String ANSWERS_COLUMN_QUESTION_ID = "QuestionId";
public static final String ANSWERS_COLUMN_ANSWER = "Answer";
public static final String ANSWERS_COLUMN_POINT = "Point";

private SQLiteDatabase mDb;

private final Context mContext;

private boolean mCreateDatabase = false;
private boolean mUpgradeDatabase = false;

/**
 * Constructor
 * Takes and keeps a reference of the passed context in order to access
 * the application's assets and resources
 * @param context
 */
public QuestionsDbAdapter(Context context) {
    super(context, DATABASE_NAME, null, context.getResources().getInteger(R.integer.questionDbVersion));

    mContext = context;
}

public void initializeDatabase(String path) {
    DATABASE_PATH = path;
    getWritableDatabase();

    if(mUpgradeDatabase) {
        mContext.deleteDatabase(DATABASE_NAME);
    }

    if(mCreateDatabase || mUpgradeDatabase) {
        try {
            copyDatabase();
        } catch (IOException e) {
            throw new Error("Error copying database");
        }
    }
}

private void copyDatabase() throws IOException {
    close();

    InputStream input = mContext.getAssets().open(DATABASE_NAME);

    String outFileName = DATABASE_PATH + DATABASE_NAME;

    OutputStream output = new FileOutputStream(outFileName);

    // Transfer bytes from the input file to the output file
    byte[] buffer = new byte[1024];
    int length;
    while ((length = input.read(buffer)) > 0) {
        output.write(buffer, 0, length);
    }

    output.flush();
    output.close();
    input.close();

    getWritableDatabase().close();
}

public QuestionsDbAdapter open() throws SQLException {
    mDb = getReadableDatabase();
    return this;
}

public void CleanUp() {
    mDb.close();
}

@Override
public void onCreate(SQLiteDatabase db) {
    mCreateDatabase = true;
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    mUpgradeDatabase = true;
}

/**
 * Public helper methods
 */

public Cursor getQuestionById(long rowId) throws SQLException {
    Cursor cursor = mDb.query(true, TABLE_QUESTIONS,
            new String[] { QUESTIONS_COLUMN_ID, QUESTIONS_COLUMN_QUESTION }, QUESTIONS_COLUMN_ID + "=" + rowId,
            null, null, null, null, null);

    return cursor;
}

public Cursor getAnswerById(long rowId) throws SQLException {
    Cursor cursor = mDb.query(true, TABLE_ANSWERS,
            new String[] { ANSWERS_COLUMN_ID, ANSWERS_COLUMN_QUESTION_ID, ANSWERS_COLUMN_ANSWER, ANSWERS_COLUMN_POINT },
            ANSWERS_COLUMN_ID + "=" + rowId,
            null, null, null, null, null);

    return cursor;
}

public Cursor getAnswersByQuestionId(long questionId) throws SQLException {
    Cursor cursor = mDb.query(true, TABLE_ANSWERS, new String[] {ANSWERS_COLUMN_ANSWER, ANSWERS_COLUMN_POINT},
            ANSWERS_COLUMN_QUESTION_ID + "=" + questionId, null, null, null, null, null);

    return cursor;
}

public long getCount() {
    String sql = "SELECT COUNT(*) FROM " + TABLE_QUESTIONS;
    SQLiteStatement statement = mDb.compileStatement(sql);
    long count = statement.simpleQueryForLong();
    return count;
}
}

Answer 1

这里不需要这个混乱的代码是你Android SQLiteAssetHelper

的好方法

Answer 2

我认为问题是你只需要将你的图像存储在移动应用程序中，但如果它的大小非常大，那么从服务器检索它，感谢@confucius对于这篇文章它确实有帮助，这里是另一个循序渐进的教程这解释了how to use sqlite browser to make a pre-loaded database in android

如何正确使用Android中预装的数据库

2 个答案: