我的第一个问题没有得到任何与此类似的回复，所以我将再试一次，但希望能更好地解释，以便你们都明白。
我正在尝试从数据库中检索一个图像，该图像存储为通过SIMPLECURSORADAPTER提取的BLOB图像。我可以存储图像，但是当我尝试检索图像时，它会给出一个错误“无法将blob转换为字符串”。我不确定为什么我会得到这个错误，因为我没有尝试将blob直接转换为字符串。
我是一个相当新的Android编程，所以我会尽可能多地获得帮助。
感谢您的时间。
栈跟踪
04-06 14:34:00.163 4145-4145/com.gnumbu.errolgreen.importedapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.gnumbu.errolgreen.importedapplication, PID: 4145
android.database.sqlite.SQLiteException: unknown error (code 0): Unable to convert BLOB to string
at android.database.CursorWindow.nativeGetString(Native Method)
at android.database.CursorWindow.getString(CursorWindow.java:438)
at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:51)
at android.widget.SimpleCursorAdapter.bindView(SimpleCursorAdapter.java:150)
at android.widget.CursorAdapter.getView(CursorAdapter.java:254)
at android.widget.AbsListView.obtainView(AbsListView.java:2344)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1270)
at android.widget.ListView.onMeasure(ListView.java:1182)
at android.view.View.measure(View.java:17430)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
at android.view.View.measure(View.java:17430)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1456)
at android.view.View.measure(View.java:17430)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
at android.view.View.measure(View.java:17430)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:453)
at android.view.View.measure(View.java:17430)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
at android.view.View.measure(View.java:17430)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
at android.view.View.measure(View.java:17430)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2560)
at android.view.View.measure(View.java:17430)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2001)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1166)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1372)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1054)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5779)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:550)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
DBAdapter.java
public class DBAdapter {
private static final String TAG = "DBAdapter"; //used for logging database version changes
// Field Names:
public static final String KEY_ROWID = "_id";
public static final String KEY_TASK = "task";
public static final String KEY_DATE = "date";
public static final String KEY_IMAGE = "image";
public static final String[] ALL_KEYS = new String[] {KEY_ROWID, KEY_TASK, KEY_DATE, KEY_IMAGE};
// Column Numbers for each Field Name:
public static final int COL_ROWID = 0;
public static final int COL_TASK = 1;
public static final int COL_DATE = 2;
public static final int COL_IMAGE = 3;
// DataBase info:
public static final String DATABASE_NAME = "dbToDo";
public static final String DATABASE_TABLE = "mainToDo";
public static final int DATABASE_VERSION = 1; // The version number must be incremented each time a change to DB structure occurs.
//SQL statement to create database
private static final String DATABASE_CREATE_SQL =
"CREATE TABLE " + DATABASE_TABLE
+ " (" + KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ KEY_TASK + " TEXT NOT NULL, "
+ KEY_DATE + " TEXT"
+ KEY_IMAGE + " BLOB"
+ ");";
private final Context context;
private DatabaseHelper myDBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx) {
this.context = ctx;
myDBHelper = new DatabaseHelper(context);
}
// Open the database connection.
public DBAdapter open() {
db = myDBHelper.getWritableDatabase();
return this;
}
// Close the database connection.
public void close() {
myDBHelper.close();
}
// Add a new set of values to be inserted into the database.
public long insertRow(String task, String date, byte[] image ) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_TASK, task);
initialValues.put(KEY_DATE, date);
initialValues.put(KEY_IMAGE, image);
// Insert the data into the database.
return db.insert(DATABASE_TABLE, null, initialValues);
}
// Delete a row from the database, by rowId (primary key)
public boolean deleteRow(long rowId) {
String where = KEY_ROWID + "=" + rowId;
return db.delete(DATABASE_TABLE, where, null) != 0;
}
public void deleteAll() {
Cursor c = getAllRows();
long rowId = c.getColumnIndexOrThrow(KEY_ROWID);
if (c.moveToFirst()) {
do {
deleteRow(c.getLong((int) rowId));
} while (c.moveToNext());
}
c.close();
}
// Return all data in the database.
public Cursor getAllRows() {
String where = null;
Cursor c = db.query(true, DATABASE_TABLE, ALL_KEYS, where, null, null, null, null, null);
if (c != null) {
c.moveToFirst();
}
return c;
}
// Get a specific row (by rowId)
public Cursor getRow(long rowId) {
String where = KEY_ROWID + "=" + rowId;
Cursor c = db.query(true, DATABASE_TABLE, ALL_KEYS,
where, null, null, null, null, null);
if (c != null) {
c.moveToFirst();
}
return c;
}
// Change an existing row to be equal to new data.
public boolean updateRow(long rowId, String task, String date, byte[] image) {
String where = KEY_ROWID + "=" + rowId;
ContentValues newValues = new ContentValues();
newValues.put(KEY_TASK, task);
newValues.put(KEY_DATE, date);
newValues.put(KEY_IMAGE, image);
// Insert it into the database.
return db.update(DATABASE_TABLE, newValues, where, null) != 0;
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase _db) {
_db.execSQL(DATABASE_CREATE_SQL);
}
@Override
public void onUpgrade(SQLiteDatabase _db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading application's database from version " + oldVersion
+ " to " + newVersion + ", which will destroy all old data!");
// Destroy old database:
_db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
// Recreate new database:
onCreate(_db);
}
}
}
PeekFragment.java
public class PeekFragment extends Fragment implements View.OnClickListener {
//Delcare Public Variables !
Time today = new Time(Time.getCurrentTimezone());
DBAdapter myDB;
EditText etTasks;
ImageView img;
ByteArrayBuffer baf ;
ImageView dbimage ;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.other_layout, container, false);
Button a = (Button) v.findViewById(R.id.addTask);
Button b = (Button) v.findViewById(R.id.deleteButton);
a.setOnClickListener(this);
b.setOnClickListener(this);
return v;
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.addTask:
today.setToNow();
String timestamp = today.format("%Y-%-m-%d %H:%M:%S");
if (!TextUtils.isEmpty(etTasks.getText().toString())) {
dbimage.buildDrawingCache();//Draws image to bitmap
Bitmap bmap = dbimage.getDrawingCache();
myDB.insertRow(etTasks.getText().toString(), timestamp, getBytes(bmap));
}
break;
case R.id.deleteButton:
myDB.deleteAll();
break;
}
populateListView();
}
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
etTasks = (EditText) getView().findViewById(R.id.editTextTask);
dbimage = (ImageView) getView().findViewById(R.id.dbImageUpload);
openDB();
// new Task_like_flag().execute();
// img =(ImageView) getView().findViewById(R.id.imageViewpicture);
populateListView();
listViewItemClick();
listViewItemLongClick();
Cursor cursor = myDB.getAllRows();
String[] fromFieldNames = new String[]{DBAdapter.KEY_ROWID, DBAdapter.KEY_TASK, DBAdapter.KEY_IMAGE};
int[] toViewIDs = new int[]{R.id.idView, R.id.resourceView, R.id.imageViewpicture};
SimpleCursorAdapter myCursorAdapter;
myCursorAdapter = new SimpleCursorAdapter(getActivity(), R.layout.tobedeletedd_view, cursor, fromFieldNames, toViewIDs, 0) {
};
ListView myList = (ListView) getView().findViewById(R.id.listView);
myList.setAdapter(myCursorAdapter);
}
/**
* public void onClick_AddTask(View v) {
* today.setToNow();
* String timestamp = today.format("%Y-%-m-%d %H:%M:%S");
* <p/>
* if (!TextUtils.isEmpty(etTasks.getText().toString())) {
* myDB.insertRow(etTasks.getText().toString(), timestamp);
* <p/>
* }
* populateListView();
* }
*/
private void openDB() {
myDB = new DBAdapter(getActivity());
myDB.open();
}
private void populateListView() {
Cursor cursor = myDB.getAllRows();
String[] fromFieldNames = new String[]{DBAdapter.KEY_ROWID, DBAdapter.KEY_TASK, DBAdapter.KEY_IMAGE};
int[] toViewIDs = new int[]{R.id.idView, R.id.resourceView, R.id.imageViewpicture};
SimpleCursorAdapter myCursorAdapter;
myCursorAdapter = new SimpleCursorAdapter(getActivity(), R.layout.tobedeletedd_view, cursor, fromFieldNames, toViewIDs, 0) {
};
ListView myList = (ListView) getView().findViewById(R.id.listView);
myList.setAdapter(myCursorAdapter);
}
private void updateTask(long id) {
Cursor cursor = myDB.getRow(id);
if (cursor.moveToFirst()) {
String task = etTasks.getText().toString();
today.setToNow();
String date = today.format("%Y-%-m-%d %H:%M:%S");
dbimage.buildDrawingCache();//Draws image to bitmap
Bitmap bmap = dbimage.getDrawingCache();
myDB.updateRow(id, task, date,getBytes(bmap));
}
cursor.close();
}
private void listViewItemClick() {
ListView myList = (ListView) getView().findViewById(R.id.listView);
myList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
updateTask(id);
populateListView();
}
});
}
private void listViewItemLongClick() {
ListView myList = (ListView) getView().findViewById(R.id.listView);
myList.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
myDB.deleteRow(id);
populateListView();
return false;
}
});
}
/**
public Bitmap convertBlobToBitmap(byte[] blobByteArray) {
Bitmap tempBitmap=null;
if(blobByteArray!=null)
tempBitmap = BitmapFactory.decodeByteArray(blobByteArray, 0, blobByteArray.length);
return tempBitmap;
}
public class Task_like_flag extends AsyncTask<String, Void, Void> {
private final ProgressDialog dialog = new ProgressDialog(getActivity());
JSONObject object_feed;
// can use UI thread here
protected void onPreExecute() {
this.dialog.setMessage("Loading...");
this.dialog.setCancelable(false);
this.dialog.show();
}
@Override
protected Void doInBackground(String... params) {
URL url = null;
try {
url = new URL("http://i.imgur.com/cWdWl6L.png");
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} //http://example.com/image.jpg
//open the connection
URLConnection ucon = null;
try {
ucon = url.openConnection();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//buffer the download
InputStream is = null;
try {
is = ucon.getInputStream();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
BufferedInputStream bis = new BufferedInputStream(is,128);
baf = new ByteArrayBuffer(128);
//get the bytes one by one
int current = 0;
try {
while ((current = bis.read()) != -1) {
baf.append((byte) current);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
today.setToNow();
String timestamp = today.format("%Y-%-m-%d %H:%M:%S");
String voteText = "Test";
myDB.insertRow(etTasks.getText().toString(), timestamp, baf.toByteArray(), voteText);
return null;
}
@Override
protected void onPostExecute(Void result) {
byte[] imageByteArray;
Bitmap theImage = null;
try{
Cursor cursor = myDB.fetchAllNotes();
// startManagingCursor(myDB);
if (cursor.moveToFirst()) {
do {
imageByteArray = cursor.getBlob(cursor.getColumnIndex(DBAdapter.KEY_IMAGE));
ByteArrayInputStream imageStream = new ByteArrayInputStream(imageByteArray);
theImage= BitmapFactory.decodeStream(imageStream);
} while (cursor.moveToNext());
}
}catch(Exception e){
Log.v("Excep", ""+e);
}
img.setImageBitmap(theImage);
if (this.dialog.isShowing()) {
this.dialog.dismiss();
}
}
}
*/
// convert from bitmap to byte array
public static byte[] getBytes(Bitmap bitmap) {
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 0, stream);
return stream.toByteArray();
}
// convert from byte array to bitmap
public static Bitmap getImage(byte[] image) {
return BitmapFactory.decodeByteArray(image, 0, image.length);
}
}
答案 0 :(得分：0)
BLOB用于存储通常具有巨大尺寸的图片音频和视频。它们由BLOB存储到二进制数据中。所以当你查询时，你得到的是byte[]。然后，您将byte[]转换为Bitmap。只是一些代码：
byte[] imagequery=null;
if(cur.moveToNext()){
imagequery=cur.getBlob(cur.getColumnIndex("image"));
}
Bitmap imagebitmap=BitmapFactory.decodeByteArray(imagequery, 0, imagequery.length);
我希望这些代码会激励你。
答案 1 :(得分：0)
我认为问题在于你的适配器，在某种程度上blob像String一样处理。
您的代码中有convertBlobToBitmap()方法已被注释掉。使用它将字节数组（加载blob）转换为图像。