android - Content Provider 没有这样的表

Question

我完全迷路了...这是我的代码:

public class MainContentProvider extends ContentProvider {
//DataBase
private WordsOpenHelper db_words;
private CategoryOpenHelper db_category;

//helper Strings to build the URI
private static String AUTHORITY = "com.ivanvoynov.dictionary.ContentProvider";
private static String BASE_PATH_WORDS = WordsOpenHelper.TABLE_NAME;
private static String BASE_PATH_CATEGORY = CategoryOpenHelper.TABLE_NAME;

//Content URI and the data types MIME
public static final Uri CONTENT_URI_WORDS = Uri.parse("content://" + AUTHORITY + "/" + BASE_PATH_WORDS);
public static final Uri CONTENT_URI_CATEGORY = Uri.parse("content://" + AUTHORITY + "/" + BASE_PATH_CATEGORY);
public static final String CONTENT_TYPE = ContentResolver.CURSOR_DIR_BASE_TYPE + BASE_PATH_WORDS;
public static final String CONTENT_ITEM_TYPE = ContentResolver.CURSOR_ITEM_BASE_TYPE + BASE_PATH_WORDS;

//our private variable to help match the URI types
private static final int ALL_ROWS_WORDS = 0;
private static final int ID_ROW_WORDS = 1;
private static final int ALL_ROWS_CATEGORY = 2;
private static final int ID_ROW_CATEGORY = 3;


//our URI matcher class to match our uri's
private static final UriMatcher sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
static{
    sUriMatcher.addURI(AUTHORITY, BASE_PATH_WORDS, ALL_ROWS_WORDS);
    sUriMatcher.addURI(AUTHORITY, BASE_PATH_WORDS + "/#", ID_ROW_WORDS);
    sUriMatcher.addURI(AUTHORITY, BASE_PATH_CATEGORY, ALL_ROWS_CATEGORY);
    sUriMatcher.addURI(AUTHORITY, BASE_PATH_CATEGORY + "/#", ID_ROW_CATEGORY);
}

@Override
public boolean onCreate() {
    db_words = new WordsOpenHelper(getContext());
    db_category = new CategoryOpenHelper(getContext());
    return false;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
    //create the query builder
    SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();


    //our database initialization
    SQLiteDatabase database;
    Cursor cursor;

    //implement check column projection later on...

    //implement all of them to return all with specific crap.
    int uriType = sUriMatcher.match(uri);
    switch (uriType){
        case ALL_ROWS_WORDS:
            //all words are asked
            database = db_words.getWritableDatabase();
            queryBuilder.setTables(WordsOpenHelper.TABLE_NAME);
            cursor = queryBuilder.query(database, projection, selection, selectionArgs, null, null, sortOrder);

            cursor.setNotificationUri(getContext().getContentResolver(), uri);
            return cursor;

        case ALL_ROWS_CATEGORY:
            //all words are asked
            database = db_category.getWritableDatabase();
            queryBuilder.setTables(db_category.TABLE_NAME);
            cursor = queryBuilder.query(database, projection, selection, selectionArgs, null, null, sortOrder);

            cursor.setNotificationUri(getContext().getContentResolver(), uri);
            return cursor;

        case ID_ROW_WORDS:
            //append to the table a new thing
            queryBuilder.setTables(db_words.TABLE_NAME);
            queryBuilder.appendWhere(db_words.KEY_ROW_ID + "=" + uri.getLastPathSegment());
            database = db_words.getWritableDatabase();
            cursor = queryBuilder.query(database, projection, selection, selectionArgs, null, null, sortOrder);

            cursor.setNotificationUri(getContext().getContentResolver(), uri);
            return cursor;
        case ID_ROW_CATEGORY:
            //this is the category's row id selection
            queryBuilder.setTables(db_category.TABLE_NAME);
            queryBuilder.appendWhere(db_category.KEY_ROW_ID + "=" + uri.getLastPathSegment());
            database = db_category.getWritableDatabase();
            cursor = queryBuilder.query(database, projection, selection, selectionArgs, null, null, sortOrder);

            cursor.setNotificationUri(getContext().getContentResolver(), uri);
            return cursor;
        default:
            throw new IllegalArgumentException("Unknown URI: " + uri + "URI TYPE = " + uriType);
    }
}

这是 Open 助手:

public class WordsOpenHelper extends SQLiteOpenHelper{

    //general info about the DataBase
    public static final String DATABASE_NAME = "dictionary.db";
    public static final String TABLE_NAME = "vocabulary";
    private static final int DATABASE_VERSION = 1;

    //DataBase columns
    public static final String KEY_ROW_ID = "_id";
    public static final String KEY_WORD = "word";
    public static final String KEY_DEFINITION = "definition";
    public static final String KEY_EXAMPLES = "examples";
    public static final String KEY_DIFFICULTY = "difficulty"; //new term
    public static final String KEY_SUBCATEGORY = "subcategory"; //new
    public static final String KEY_COLOR = "color"; //new
    public static final String KEY_LEARNED_FLAG = "learned_flag"; //new
    public static final String KEY_ARCHIVED_FLAG = "archived_flag"; //new
    public static final String KEY_TIMES_VIEWED = "times_viewed"; //count
    public static final String KEY_TIMES_CORRECT = "times_correct"; //new coint
    public static final String KEY_TIMES_INCORRECT = "times_incorrect"; //new
    public static final String KEY_TIMES_SKIPPED = "times_skipped"; //new
    public static final String KEY_LANGUAGE = "language"; //newone
    public static final String KEY_SYNONYMS = "synonyms";
    public static final String KEY_PART_OF_SPEECH = "part_of_speech";
    public static final String KEY_CATEGORIES = "categories";
    public static final String KEY_RECENT_FLAG = "recent_flag";
    public static final String KEY_UNDEFINED_FLAG = "defined_flag";

    //projection used in conjunction with other crap to form URI
    public static final String[] PROJECTION = new String[]{
            KEY_ROW_ID,
            KEY_WORD,
            KEY_DEFINITION,
            KEY_DIFFICULTY,
            KEY_EXAMPLES,
            KEY_SYNONYMS,
            KEY_PART_OF_SPEECH,
            KEY_CATEGORIES,
            KEY_RECENT_FLAG,
            KEY_UNDEFINED_FLAG,
            KEY_SUBCATEGORY,
            KEY_COLOR,
            KEY_LEARNED_FLAG,
            KEY_ARCHIVED_FLAG,
            KEY_TIMES_VIEWED,
            KEY_TIMES_CORRECT,
            KEY_TIMES_INCORRECT,
            KEY_TIMES_SKIPPED,
            KEY_LANGUAGE
    };

    //the table raw SQLite command to create it.
    private static final String DICTIONARY_TABLE_CREATE =
            "CREATE TABLE " + TABLE_NAME + " ("
                    + KEY_ROW_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
                    + KEY_WORD + " TEXT,"
                    + KEY_DEFINITION + " TEXT,"
                    + KEY_DIFFICULTY + " INTEGER,"
                    + KEY_EXAMPLES + " TEXT,"
                    + KEY_SYNONYMS + " TEXT,"
                    + KEY_PART_OF_SPEECH +" TEXT, "
                    + KEY_CATEGORIES + " TEXT, "
                    + KEY_RECENT_FLAG + " TEXT,"
                    + KEY_UNDEFINED_FLAG + " TEXT,"
                    + KEY_SUBCATEGORY + " TEXT,"
                    + KEY_COLOR + " TEXT,"
                    + KEY_LEARNED_FLAG + " TEXT,"
                    + KEY_ARCHIVED_FLAG + " TEXT,"
                    + KEY_TIMES_VIEWED + " INTEGER,"
                    + KEY_TIMES_CORRECT + " INTEGER,"
                    + KEY_TIMES_INCORRECT + " INTEGER,"
                    + KEY_TIMES_SKIPPED + " INTEGER,"
                    + KEY_LANGUAGE + " TEXT "
                    + ");";


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

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(DICTIONARY_TABLE_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVerson, int newVersion){
        //delete the table if it exists when upgrading
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }
}

我一直收到这个错误:

Caused by: android.database.sqlite.SQLiteException: no such table: vocabulary (code 1): , while compiling: SELECT _id, word, definition, difficulty, examples, synonyms, part_of_speech, categories, recent_flag, defined_flag, subcategory, color, learned_flag, archived_flag, times_viewed, times_correct, times_incorrect, times_skipped, language FROM vocabulary
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
        at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
        at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
        at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
        at android.database.sqlite.SQLiteQueryBuilder.query(SQLiteQueryBuilder.java:400)
        at android.database.sqlite.SQLiteQueryBuilder.query(SQLiteQueryBuilder.java:294)
        at com.ivanvoynov.dictionary.ContentProvider.MainContentProvider.query(MainContentProvider.java:80)

我浪费了整个晚上... 据我了解，表尚未创建。为什么还没有创建我不明白。当我重新安装应用程序时，这就是我不断得到的。

Answer 1

根据评论，您有两个使用相同数据库文件的数据库助手。这是发生了什么:

1. Helper 1 数据库是在第一次调用 getWritableDatabase() 时创建的。助手的 onCreate() 被调用。数据库文件的版本设置为 DATABASE_VERSION。

2. Helper 2 的数据库在调用其 getWritableDatabase() 时打开。数据库文件已存在且版本正确，因此不会调用 onUpgrade() 或 onCreate()。但是这个数据库没有 helper 2 的表。

解决方案:每个数据库文件只有一个数据库助手。您可以在一个助手中拥有多个表。