java - 从 SQLite 数据库添加和检索图像

Question

我创建了一个表和数据库来存储“标题”“描述”和“图像使用 BLOB”。但是我无法从 SQLite 数据库检索图像。我认为我的代码是错误的。单击下一步按钮时，我的应用程序显示新的描述和图像。我应该将所有图像保存在文件夹中的哪里？

数据库助手类

void onCreate(SQLiteDatabase db) {
  this.db = db;
  SQL_CREATE_WORD_TABLE = "CREATE TABLE " +
            WordsContract.WordsTable.TABLE_NAME + " ( " +
            WordsContract.WordsTable._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
            WordsContract.WordsTable.COLUMN_GROUP_NAME + " TEXT, " +
            WordsContract.WordsTable.COLUMN_NAME_WORD + " TEXT, " +
            WordsContract.WordsTable.COLUMN_IMAGE + " BLOB " +
            ")";
    db.execSQL(SQL_CREATE_WORD_TABLE);

  fillWordsTable();

}
private void fillWordsTable() {
    Word f1 = new Word("FRUIT","Grapes","grape.png");
    addQuestion(f1);
    Word f2 = new Word("FRUIT","Longon","longon.png");
    addQuestion(f2);
}
private void addQuestion(Word word) {
    ContentValues cv = new ContentValues();
    cv.put(WordsContract.WordsTable.COLUMN_GROUP_NAME,word.getGroup());
    cv.put(WordsContract.WordsTable.COLUMN_NAME_WORD,word.getNameWord());
    cv.put(WordsContract.WordsTable.COLUMN_IMAGE,word.getImage());
    db.insert(WordsContract.WordsTable.TABLE_NAME,null,cv);
}
public List<Word> getAllWords(){
    List<Word> wordList = new ArrayList<>();
    db = getReadableDatabase();
    Cursor c = db.rawQuery("SELECT * FROM "+ WordsContract.WordsTable.TABLE_NAME,null);
    if(c.moveToFirst()){
        do{
            Word word = new Word();word.setNameWord(c.getString(c.getColumnIndex(WordsContract.WordsTable.COLUMN_NAME_WORD)));
        word.setImage(c.getString(c.getColumnIndex(WordsContract.WordsTable.COLUMN_IMAGE)));
            wordList.add(word);
        } while (c.moveToNext());
    }
    c.close();
    return wordList; }

类词联系方式

public static class WordsTable implements BaseColumns{
    public static final String TABLE_NAME = "word_questions";
    public static final String COLUMN_GROUP_NAME = "groups";
    public static final String COLUMN_NAME_WORD = "words";
    public static final String COLUMN_IMAGE = "images";
}

类MainActivity

public void onCreate(){
   mImageView = (ImageView) findViewById(R.id.image_view);
   WordDbHelper dbHelper = new WordDbHelper(this);

   mWordList = dbHelper.getAllWords();

   wordCountTotal = mWordList.size();
   Collections.shuffle(mWordList);
showNextQuestion();}

public void showNextQuestion(){
     if(wordCounter < wordCountTotal){
        currentWord = mWordList.get(wordCounter);

        titleGroup.setText(currentWord.getGroup());
        nameWord.setText(currentWord.getNameWord());
        mImageView.setImageBitmap(currentWord.getImage());

        wordCounter++;

    }else{
        finish();
    }
}

错误:不兼容的类型:字符串无法转换为位图

Answer 1

替换这一行:

 word.setImage(c.getString(c.getColumnIndex(WordsContract.WordsTable.COLUMN_IMAGE)));

与:

word.setImage(c.getBlob(c.getColumnIndex(WordsContract.WordsTable.COLUMN_IMAGE)));

并加载图像:

mImageView.setImageBitmap(BitmapFactory.decodeByteArray( currentWord.getImage(), 
    0,currentWord.getImage().length));