Android 如何从数据库中无误地获取图像？

我使用Facebook登录，抓取个人资料图像，保存在数据库中，尝试恢复数据库图像，然后在ImageView中设置，但没有成功

我想了解原因，以及可能的解决方案

来自Logcat的错误：

活动：

byte[] teste = databaseHelper.getImage();
if (teste != null) {
    Bitmap bitmap = BitmapFactory. decodeByteArray(teste, 0, teste.length);
    img.setImageBitmap(bitmap);
}

布局：

Facebook的登录代码：

---

在访问之前，将光标移动到开头：

public byte[] getImage(){

    SQLiteDatabase db = helper.getReadableDatabase();
    String[] columns = {DatabaseHelper.IMAGE};
    Cursor cursor = db.query(DatabaseHelper.TABLE_NAME, columns, null, null, null, null, null);
    if (cursor.moveToFirst()) {
        return cursor.getBlob(cursor.getColumnIndex(DatabaseHelper.IMAGE));
    }
    return null;
}

并在访问返回值之前检查空值

在您的活动中：

byte[] teste = databaseHelper.getImage();
if (teste != null) {
    Bitmap bitmap = BitmapFactory. decodeByteArray(teste, 0, teste.length);
    img.setImageBitmap(bitmap);
}

---

如何检查空值？谢谢！现在我有：java.lang.RuntimeException:无法启动活动组件信息{br.com.**/br.com.**.Perfil}:java.lang.IllegalStateException:无法从游标窗口读取第0行第2列。确保光标在从中访问数据之前已正确初始化。表列是否具有相同的数组？从0开始？但是0是id，是一个名字，2岁和3岁是图像？或者0是名称，1是旧的，2是图像？很好！这次我没有出错。但它在ImageView中未设置图像。为什么要将返回值设为空？如果在游标之后，您是否也在if中返回？

    public class Database {

DatabaseHelper helper;

public Database(Context context){
    helper = new DatabaseHelper(context);
}

public long insertData(String name, String idade, byte[] image){
    SQLiteDatabase db = helper.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(DatabaseHelper.NAME, name);
    contentValues.put(DatabaseHelper.IDADE, idade);
    contentValues.put(DatabaseHelper.IMAGE, image);

    long id = db.insert(DatabaseHelper.TABLE_NAME, null, contentValues);
    return id;
}


public byte[] getImage(){

    //select name, password from vivztable where name = 'anky';
    SQLiteDatabase db = helper.getWritableDatabase();
    String[] columns = {DatabaseHelper.IMAGE};
    Cursor cursor = db.query(DatabaseHelper.TABLE_NAME, columns, null, null, null, null, null);
    StringBuffer buffer = new StringBuffer();



    byte[] personImage = cursor.getBlob(2); //////THIS LINE IS GIVING ERROR



    return personImage;
}


public String getAllData(){
    SQLiteDatabase db = helper.getWritableDatabase();
    String[] columns = {DatabaseHelper.UID, DatabaseHelper.NAME, DatabaseHelper.IDADE};
    Cursor cursor = db.query(DatabaseHelper.TABLE_NAME, columns, null, null, null, null, null);
    StringBuffer buffer = new StringBuffer();

    while (cursor.moveToNext()){
        int cid = cursor.getInt(0);
        String name = cursor.getString(1);
        String idade = cursor.getString(2);
        buffer.append(cid+""+name+""+idade+"\n");
    }
    return buffer.toString();
}

public String getName(){

    //select name, password from vivztable where name = 'anky';
    SQLiteDatabase db = helper.getWritableDatabase();
    String[] columns = {DatabaseHelper.NAME};
    Cursor cursor = db.query(DatabaseHelper.TABLE_NAME, columns, null, null, null, null, null);
    StringBuffer buffer = new StringBuffer();
//DatabaseHelper.NAME+" = '"+name+"'"
    cursor.moveToLast();
        int index1 = cursor.getColumnIndex(DatabaseHelper.NAME);
        String personName = cursor.getString(index1);
        buffer.append(personName);

    return buffer.toString();
}

public String getIdade(){

    //select name, password from vivztable where name = 'anky';
    SQLiteDatabase db = helper.getWritableDatabase();
    String[] columns = {DatabaseHelper.IDADE};
    Cursor cursor = db.query(DatabaseHelper.TABLE_NAME, columns, null, null, null, null, null);
    StringBuffer buffer = new StringBuffer();
    //DatabaseHelper.NAME+" = '"+name+"'"
    cursor.moveToLast();
    int index1 = cursor.getColumnIndex(DatabaseHelper.IDADE);
    String idade = cursor.getString(index1);
    buffer.append(idade);

    return buffer.toString();
}

static class DatabaseHelper extends SQLiteOpenHelper{

    private static final String UID = "_id";
    private static final String NAME = "name";
    private static final String IDADE = "idade";
    private static final String EMAIL = "email";
    private static final String IMAGE = "image";

    private static final String DATABASE_NAME = "perfildatabase";
    private static final String TABLE_NAME  = "PERFILTABLE";
    private static final int DATABASE_VERSION = 1;

    private static final String CREATE_TABLE = "create table "+ TABLE_NAME + " ("+UID+" integer primary key autoincrement, "+ NAME + " VARCHAR (255), "+ IDADE + " VARCHAR (255), "+ IMAGE + " BLOB);";

    private static final String DROP_TABLE = "DROP TABLE IF EXISTS "+TABLE_NAME;

    private Context context;
    //MeuOpenHelper openHelper;
    //SQLiteDatabase db;

    public DatabaseHelper(Context context){
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        this.context=context;
        Message.message(context, "constructor called");
    }

    /**
     private class MeuOpenHelper extends SQLiteOpenHelper {
     MeuOpenHelper(Context context){
     super(context, NAME_BANCO, null, VERSAO_BANCO);

     }
     **/
    @Override
    public void onCreate(SQLiteDatabase db){
        try {
            db.execSQL(CREATE_TABLE);
            Message.message(context, "onCreate called");
        } catch (SQLException e){
            Message.message(context,""+e);
        }

    }


    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
        try {
            db.execSQL(DROP_TABLE);
            onCreate(db);
            Message.message(context, "onUpgrade called");
        } catch (SQLException e){
            Message.message(context,""+e);
        }

    }

}
    }

public class MainFragment extends android.support.v4.app.Fragment {

private Database databaseHelper;
private AccessTokenTracker mTokenTracker;
private ProfileTracker mProfileTracker;
private TextView mTextDetails;
private ImageView imageTeste;
private CallbackManager mCallbackManager;
private FacebookCallback<LoginResult> mCallback = new FacebookCallback<LoginResult>() {
    @Override
    public void onSuccess(LoginResult loginResult) {
        AccessToken accessToken = loginResult.getAccessToken();
        Profile profile = Profile.getCurrentProfile();
        displayWelcomeMessage(profile);


    }
    @Override
    public void onCancel() {
    }

    @Override
    public void onError(FacebookException e) {

    }
};
public MainFragment() {
    // Required empty public constructor
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    FacebookSdk.sdkInitialize(getActivity().getApplicationContext());
    mCallbackManager = CallbackManager.Factory.create();
    AccessTokenTracker tracker = new AccessTokenTracker() {
        @Override
        protected void onCurrentAccessTokenChanged(AccessToken old, AccessToken newToken) {

        }
    };

    ProfileTracker profileTracker = new ProfileTracker() {
        @Override
        protected void onCurrentProfileChanged(Profile oldProfile, Profile newProfile) {
            //displayWelcomeMessage(newProfile);
        }
    };
    tracker.startTracking();
    profileTracker.startTracking();
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    LoginButton loginButton = (LoginButton)view.findViewById(R.id.login_button);
    loginButton.setReadPermissions("user_friends");
    loginButton.setFragment(this);
    loginButton.registerCallback(mCallbackManager, mCallback);

    //mTextDetails = (TextView) view.findViewById(R.id.text_details);
    imageTeste = (ImageView) view.findViewById(R.id.imageTeste);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_main, container, false);
}

public void displayWelcomeMessage(Profile profile){
    if (profile != null){

        databaseHelper = new Database(getActivity());
        String name = profile.getName();
        String idade = profile.getLastName();
        String userIds = profile.getId();


        Bitmap b = ((BitmapDrawable)imageTeste.getDrawable()).getBitmap();

        int bytes = b.getWidth()*b.getHeight()*4;


         ByteBuffer buffer = ByteBuffer.allocate(bytes); //Create a new buffer
         b.copyPixelsToBuffer(buffer); //Move the byte data to the buffer


         byte[] image = buffer.array();


         long id = databaseHelper.insertData(name, idade, image);
         if(id < 0){
         Message.message(getActivity(), "Unsuccessful");
         } else{
         Message.message(getActivity(), "Successfully Inserted a Row");
         }

    }

}


 public Bitmap getUserPic(String userID) {
 String imageURL;
 Bitmap bitmap = null;
 //Log.d(TAG, "Loading Picture");
 imageURL = "http://graph.facebook.com/"+userID+"/picture?type=small";
 try {
 bitmap = BitmapFactory.decodeStream((InputStream)new URL(imageURL).getContent());
 } catch (Exception e) {
 Log.d("TAG", "Loading Picture FAILED");
 e.printStackTrace();
 }
 return bitmap;
 }


@Override
public void onResume() {
    super.onResume();
    Profile profile = Profile.getCurrentProfile();
    displayWelcomeMessage(profile);
}

@Override
public void onStop() {
    super.onStop();
    //mTokenTracker.stopTracking();
    //mProfileTracker.stopTracking();
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    mCallbackManager.onActivityResult(requestCode, resultCode, data);
}
}

public byte[] getImage(){

    SQLiteDatabase db = helper.getReadableDatabase();
    String[] columns = {DatabaseHelper.IMAGE};
    Cursor cursor = db.query(DatabaseHelper.TABLE_NAME, columns, null, null, null, null, null);
    if (cursor.moveToFirst()) {
        return cursor.getBlob(cursor.getColumnIndex(DatabaseHelper.IMAGE));
    }
    return null;
}

byte[] teste = databaseHelper.getImage();
if (teste != null) {
    Bitmap bitmap = BitmapFactory. decodeByteArray(teste, 0, teste.length);
    img.setImageBitmap(bitmap);
}