所以，我有一个从url下载图像并将其传输到byte []的方法。然后，我把那个byte []放到我的数据库中。我在我的专栏中使用了blob类型，但它给了我一个错误。以下是从url：
下载图像的方法public static byte[] getByteFromUrl(URL src) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
InputStream is = null;
try {
is = src.openStream();
byte[] byteChunk = new byte[4096]; // Or whatever size you want to read in at a time.
int n;
while ((n = is.read(byteChunk)) > 0) {
baos.write(byteChunk, 0, n);
}
return baos.toByteArray();
} catch (IOException e) {
System.err.printf("Failed while reading bytes from %s: %s", src.toExternalForm(), e.getMessage());
e.printStackTrace();
// Perform any other exception handling that's appropriate.
} finally {
if (is != null) {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
和插入数据库的方法：
/**
* Method for adding UserData into local database
*
* @param userData object that has all the user data information
* @param id id of the user
*/
public void addUserData(UserData userData, long id, byte[] picture) {
SQLiteDatabase db = getWritableDatabase();
ContentValues values = new ContentValues();
values.put(USER_DATA_ID, id);
values.put(USER_DATA_FIRST_NAME, userData.getFistName());
values.put(USER_DATA_LAST_NAME, userData.getLastName());
values.put(USER_DATA_NICK_NAME, userData.getNickname());
values.put(USER_DATA_DISPLAY_NAME, userData.getHowPeopleSeeMe());
values.put(USER_DATA_EMAIL, userData.getEmail());
values.put(USER_DATA_PHONE_NUMBER, userData.getMobilePhoneNumber());
values.put(USER_DATA_GENDER, userData.getGender());
values.put(USER_DATA_RATING, userData.getReliabilityRating());
values.put(USER_DATA_PASSWORD, userData.getPassword());
values.put(USER_DATA_PICTURE, picture);
db.insert(TABLE_USER_DATA, null, values);
}
现在，一切顺利，直到我想从数据库中获取所有内容：
/**
* Method that fetches user data from local database
*
* @return UserData object is returned
*/
public UserData getUserData() {
UserData userData = new UserData();
SQLiteDatabase db = getReadableDatabase();
String selectQuery = "SELECT * FROM " + TABLE_USER_DATA;
Cursor c = db.rawQuery(selectQuery, null);
if (c.moveToFirst()) {
do {
long id = c.getLong(0);
userData.setFistName(c.getString(1));
userData.setLastName(c.getString(2));
userData.setNickname(c.getString(3));
userData.setHowPeopleSeeMe(c.getString(4));
userData.setEmail(c.getString(5));
userData.setMobilePhoneNumber(c.getString(6));
userData.setGender(c.getInt(7));
userData.setPicture(c.getBlob(8) != null ? getImage(c.getBlob(8)) : null);
userData.setReliabilityRating(c.getInt(9));
userData.setPassword(c.getString(10));
return userData;
} while (c.moveToNext());
}
c.close();
return null;
}
其中getImage方法是：
/**
* Method for converting bytes to bitmap
*
* @param image bytes[] that we are converting to bitmap
* @return bitmap image
*/
public Bitmap getImage(byte[] image) {
return BitmapFactory.decodeByteArray(image, 0, image.length);
}
我接下来的错误是：
12-28 13:41:32.348 8057-8057/share.advice.khalifa.adviceshare E/CursorWindow: Failed to read row 0, column 0 from a CursorWindow which has 0 rows, 11 columns.
12-28 13:41:32.349 8057-8057/share.advice.khalifa.adviceshare D/AndroidRuntime: Shutting down VM
12-28 13:41:32.349 8057-8057/share.advice.khalifa.adviceshare E/AndroidRuntime: FATAL EXCEPTION: main
Process: share.advice.khalifa.adviceshare, PID: 8057
java.lang.RuntimeException: Unable to start activity ComponentInfo{share.advice.khalifa.adviceshare/share.advice.khalifa.adviceshare.ui.activities.MainActivity}: java.lang.IllegalStateException: Couldn't read row 0, col 0 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.IllegalStateException: Couldn't read row 0, col 0 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.database.CursorWindow.nativeGetLong(Native Method)
at android.database.CursorWindow.getLong(CursorWindow.java:511)
at android.database.AbstractWindowedCursor.getLong(AbstractWindowedCursor.java:75)
at share.advice.khalifa.adviceshare.io.SQLDatabase.getUserData(SQLDatabase.java:178)
at share.advice.khalifa.adviceshare.io.model.Model.setUpModel(Model.java:179)
at share.advice.khalifa.adviceshare.ui.activities.MainActivity.onCreate(MainActivity.java:115)
at android.app.Activity.performCreate(Activity.java:6251)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
答案 0 :(得分：1)
我不是Android专家，但我对c.getLong(0);有点担心。
Failed to read row 0, column 0 from a CursorWindow which has 0 rows, 11 columns
你的光标是否返回0行？
答案 1 :(得分：1)
在您将数据插入数据库的updateUserData方法中，我没有看到实际添加到数据库中的图像数据。也许这就是问题？
答案 2 :(得分：0)
好的，所以，你想这样做：
在创建时检查您要放置图片的目录是否存在：
// DownloadImage AsyncTask
private class DownloadImage extends AsyncTask<String, Void, byte[]> {
UserData userData;
public DownloadImage(UserData userData) {
this.userData = userData;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected byte[] doInBackground(String... URL) {
try {
return ViewUtils.getByteFromUrl(new URL(URL[0]));
} catch (MalformedURLException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(byte[] result) {
File photo = new File(getCacheDir() + "/profile_picture/", "photo.jpg");
if (photo.exists()) {
photo.delete();
}
try {
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(photo));
bos.write(result);
bos.flush();
bos.close();
} catch (java.io.IOException e) {
Log.e("PictureDemo", "Exception in photoCallback", e);
}
}
}
现在，您要在byte []：
中从URL下载ImageViewUtils.getByteFromUrl(new URL(URL[0]));
其中
public static byte[] getByteFromUrl(URL src) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
InputStream is = null;
try {
is = src.openStream();
byte[] byteChunk = new byte[4096]; // Or whatever size you want to read in at a time.
int n;
while ((n = is.read(byteChunk)) > 0) {
baos.write(byteChunk, 0, n);
}
return baos.toByteArray();
} catch (IOException e) {
System.err.printf("Failed while reading bytes from %s: %s", src.toExternalForm(), e.getMessage());
e.printStackTrace();
// Perform any other exception handling that's appropriate.
} finally {
if (is != null) {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
是
dnx run &
现在您已成功将图像保存到本地存储。