如何在sqlite数据库中插入图像 [英] How can I insert image in a sqlite database
本文介绍了如何在sqlite数据库中插入图像的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我想使用此数据库代码将相机中的图像放置到数据库中.保存按钮和预览按钮的代码应该是什么?
I want to put an image from camera to database using this database code. What should be the code for the save button and the preview button?
public class databases extends SQLiteOpenHelper {
public static final String data = "student.db";
public static final String TABLE_NAME = "Student_TABLE";
public static final String COL_1 = "Fname";
public static final String COL_2 = "password";
public static final String COL_3 = "Fathers_name";
public static final String COL_4 = "Roll";
public static final String COL_5 = "Image";
public databases(Context context) {
super(context, data, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table " + TABLE_NAME + " (Fname TEXT,password TEXT,Fathers_name TEXT,Roll TEXT PRIMARY KEY,Image BLOB)");
}
现在，这是包含相应按钮的活动代码.
Now This is the activity code containing the respective buttons.
public class home_page extends AppCompatActivity {
Button lout,homepage,showperson,picture;static final int REQUEST_IMAGE_CAPTURE = 1;
TextView showit;
String userid,pwrd,r2,r3,r4;
databases dbss;
public void getterclass(String m)
{
userid=m;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_page);
lout = (Button) findViewById(R.id.out);
homepage = (Button) findViewById(R.id.home);
showit=(TextView) findViewById(R.id.showtextdata);
showperson=(Button)findViewById(R.id.showdata);
picture=(Button)findViewById(R.id.images);
dbss=new databases(home_page.this);
getSupportActionBar().hide();
homepage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent redirect=new Intent(home_page.this,home_page.class);
startActivity(redirect);
}
});
lout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent logout=new Intent(home_page.this,log_in.class);
startActivity(logout);
}
});
showperson.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Cursor sh=dbss.givedata(userid);
StringBuffer buf=new StringBuffer();
buf.append("First name :" + sh.getString(0) + "\n");
buf.append("password :" + sh.getString(1) + "\n");
buf.append("Father's name :" + sh.getString(2) + "\n");
buf.append("Roll :" + sh.getString(3) + "\n\n");
showit.setText(buf.toString());
}
});
picture.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
}
databases help=new databases(home_page.this);
}
});
getterclass()只不过是将用户的个人信息检索到其他活动中，但是当我尝试在同一活动中显示数据时，该方法就无法正常工作.
The getterclass() is nothing but to retrieve the personal information of the user into other activity however that isn't working as well when I try to display the data to in the same activity.
推荐答案
您将图像提取为字节[]，然后将其转换为字节，为十六进制字符串，然后将该字符串括在 X' 您的十六进制字符串 '
You extract the image as a byte[] and then either convert that to the bytes, as a string of hexadecimal characters and then enclose that string in X' your_hexadecimal_string '
- 例如可能是
X'FFFEFDFCFBFA9........'
并使用该字符串作为通过本机SQL插入的值
and use that string as the value to insert via native SQL
- 例如
INSERT INTO your_table (image_column) VALUES(X'FFFEFDFCFBFA9........')
或者您可以使用SQliteDatbase 插入便捷方法，该方法将Contentvalues对象作为第三个参数.您可以按照以下方式设置Contentvalues对象
Or you could use the SQliteDatbase insert convenience method, which takes a Contentvalues object as the 3rd parameter. You'd setup the Contentvalues object something along the lines of
ContentValues cv = new Contentvalues();
cv.put("Image",your_image_as_a_byte_array);
db.insert("the_table_name",null,cv);
但是，存储图像可能会很麻烦，因此不建议存储图像，尤其是当图像的平均大小超过10万时.
However, storing images can be troublesome and it is not recommended to store images, especially if they are over about 100k in size on average.
如果图像接近或大于2M，您将无法使用标准的Android SQLite API检索该图像，因为CursorWindow的限制为2M.即使在1M时，您也可能在CursorWindow中获得1张图像.
If an image is near to or greater than 2M you will be unable to retrieve that image using the standard Android SQLite API as a CursorWindow has a limitation of 2M. Even at 1M you could perhaps get 1 image within a CursorWindow.
推荐的方法是存储图像的路径或部分路径，并在需要时通过其路径检索图像.
The recommended method is to store the path or part of the path to the image and to retrieve the image via it's path when required.
说(上面的)，以下是一个应用程序，它将在图像小于100K时将图像存储在数据库中(public static final int MAX_FILE_SIZE = 100 * 1024;)或存储路径并通过路径或数据库检索图像到存储的内容.
Saying that (the above), the following is an App that will either store the image in the Database if it is below 100K (public static final int MAX_FILE_SIZE = 100 * 1024;) or store the path and either retrieve the image via the path or the database according to what was stored.
该应用程序具有两个带有图像描述的ListView(最右边包括图像的路径).单击任意一个中的项目都会显示图像.
The App has two ListViews with the images descriptions (the rightmost includes the path to the image). Clicking on an item in either displays the image.
例如
有许多图像的数量超过100k，其中一个funny.png图像的数量低于100k:-
There are a number of images most over 100k, one funny.png is below 100k :-
对于此示例，图像已放置在Res文件夹的Raw文件夹中，然后将它们复制到data/data/files/images文件夹(其中代表应用程序包的名称):-
The images have been placed into the Raw folder of the Res folder for this example, they are then copied to data/data/files/images folder (where represents the name of the App's package):-
DatabaseHelper DBHelper.java 是:-
The DatabaseHelper, DBHelper.java is :-
public class DBHelper extends SQLiteOpenHelper {
public static final String DBNAME = "images.db";
public static final int DBVERSION = 1;
// The maximum size of an image that should be stored 100K
public static final int MAX_FILE_SIZE = 100 * 1024;
public static final String TB_IMAGE = "image";
public static final String COL_IMAGE_ID = BaseColumns._ID;
public static final String COL_IMAGE_PATH = "image_path";
public static final String COL_IMAGE_NAME = "image_name";
public static final String COl_IMAGE_DESCRIPTION = "image_description";
public static final String COL_IMAGE_SIZE = "image_size";
public static final String COL_IMAGE_IMAGE = "image";
SQLiteDatabase mDB;
/**
* Construct DBHelper, note that it will open the database and
* thus create it if it doesn't exist
* @param context a context from the invoking activity
*/
public DBHelper(Context context) {
super(context, DBNAME, null, DBVERSION);
mDB = this.getWritableDatabase();
}
/**
* Create the table(s)
* @param db
*/
@Override
public void onCreate(SQLiteDatabase db) {
String crtsql = "CREATE TABLE IF NOT EXISTS " + TB_IMAGE +
"(" +
COL_IMAGE_ID + " INTEGER PRIMARY KEY, " +
COL_IMAGE_PATH + " TEXT UNIQUE, " +
COL_IMAGE_NAME + " TEXT, " +
COl_IMAGE_DESCRIPTION + " TEXT, " +
COL_IMAGE_SIZE + " INTEGER, " +
COL_IMAGE_IMAGE + " BLOB DEFAULT x'00'" +
")";
db.execSQL(crtsql);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
/**
* Return a Cursor with all the rows from the image table
* @return The Cursor
*/
public Cursor getImageList() {
return mDB.query(TB_IMAGE,null,null,null,null,null,null);
}
/**
* Store an image row in the image table, noting that is the image
* size is small than the max size that the image will be stored as a blob
* otherwise a blob of 1 byte is stored due to the default value.
* @param path the path to the image
* @param description a description for the image
* @return the id (rowid) of the row
*/
public long addImageFromPath(String path, String description) {
ContentValues cv = new ContentValues();
File f = new File(path);
InputStream is;
// If the file doesn't exist don't store a row
if (!f.exists()) {
return -1;
}
// Always store the name, description, path and size
cv.put(COL_IMAGE_NAME,f.getName());
cv.put(COl_IMAGE_DESCRIPTION,description);
cv.put(COL_IMAGE_SIZE,f.length());
cv.put(COL_IMAGE_PATH,f.getAbsolutePath());
// If the size is less than the max then get the filestream
// and convert to a byte[].
// Note if larger then the max file size the default x'00' blob
// will be applied
if (f.length() < MAX_FILE_SIZE) {
byte[] buffer = new byte[(int) f.length()];
try {
is = new FileInputStream(f);
is.read(buffer);
} catch (IOException e) {
e.printStackTrace();
return -1;
}
cv.put(COL_IMAGE_IMAGE,buffer);
}
// Do the insert
return mDB.insert(TB_IMAGE,null,cv);
}
/**
* get the image as a bitmap from the DB if stored, otherwise get it from
* the file, according to the id.
* @param id the id of the row in the image table
* @return the bitmap to be returned (note may be empty bitmap)
*/
public Bitmap getImage(long id) {
byte[] ba = new byte[0];
// If the image is stored in the DB then extract and return the bitmap
if (isStoredAsImage(id)) {
return getImageAsBitMap(id);
}
// If not then get the respective row from the DB
Cursor csr = mDB.query(
TB_IMAGE,
null,
COL_IMAGE_ID+"=?",
new String[]{String.valueOf(id)},
null,
null,
null
);
// Prepare to convert the path to a file
String path = ""; //<<<< default to empty path
File f = new File(path); //<<< default to empty file
// If a valid row was found get the path and File from the row
if (csr.moveToFirst()) {
path = csr.getString(csr.getColumnIndex(COL_IMAGE_PATH));
f = new File(path);
}
// done with the cursor so close it
csr.close();
// If the file exists then return the Bitmap
if (f.exists()) {
return BitmapFactory.decodeFile(f.getAbsolutePath());
}
// return an empty bitmap
return BitmapFactory.decodeByteArray(ba,0,ba.length);
}
/**
* Check to see if an image is stored in the DB,
* note assumes anything less than 8 bytes isn't an image
* @param id the id of the row in the image table
* @return true if like an image is stored, otherwise false
*/
private boolean isStoredAsImage(long id) {
boolean rv = true;
byte[] ba = new byte[0];
// Get the respective row from the image table
Cursor csr = mDB.query(
TB_IMAGE,
null,
COL_IMAGE_ID+"=?",
new String[]{String.valueOf(id)},
null,
null,
null
);
// If a row was found get the blob into byte array ba
// if not then ready to return false
if (csr.moveToFirst()) {
ba = csr.getBlob(csr.getColumnIndex(COL_IMAGE_IMAGE));
} else {
rv = false;
}
// If the byte array ba is less then 8 bytes then ready to return false
if (ba == null || ba.length < 8) {
rv = false;
}
// done with the Cursor so close it
csr.close();
// return the result
return rv;
}
/**
* get the image (assumes isStoredAsImage is used prior to invocation)
* @param id the id of the respective row
* @return the bitmap (may be 0 length)
*/
private Bitmap getImageAsBitMap(long id) {
byte[] ba = new byte[0];
Bitmap bmp;
Cursor csr =mDB.query(
TB_IMAGE,
null,
COL_IMAGE_ID+"=?",
new String[]{String.valueOf(id)},
null,
null,
null
);
if (csr.moveToFirst()) {
ba = csr.getBlob(csr.getColumnIndex(COL_IMAGE_IMAGE));
}
csr.close();
return BitmapFactory.decodeByteArray(ba,0,ba.length);
}
}
调用活动 MainActivity.java 是:-
public class MainActivity extends AppCompatActivity {
public static final String IMAGES_DIRECTORY = "images";
private static File images_file;
ArrayAdapter<String> mAdapter;
ListView mListView01, mListView02;
ArrayList<String> mImages;
CursorAdapter mCsrAdapter;
Cursor mCsr;
ImageView mImageView;
DBHelper mDBHlpr;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// get the View/Viewgroup IDs
mListView01 = this.findViewById(R.id.listview001); // File List
mListView02 = this.findViewById(R.id.listview002); // DB List
mImageView = this.findViewById(R.id.imageview001); // Image display
// get an instance of the DBHelper
mDBHlpr = new DBHelper(this);
// Copy images from raw folder to data/data/<package>/Files/images
// Also store all the images in the Database (or not depedning upon size)
getImagesFile(this);
if (getImagesCount() < 1) {
loadRawImages();
storeImagesToDB();
}
// Setup the two ListViews to display image name lists
displayList();
displayListFromDB();
// setup the file list so that when an item is clicked the image is displayed
mListView01.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
String imagename = mListView01.getItemAtPosition(i).toString();
displayImage(imagename);
}
});
// setup the DB list so that when an item is clicked the image is displayed
mListView02.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
displayDBImage(l);
}
});
}
/**
* Store the images in the images folder to the DB giving then a calculated description
* e.g. image1, image2 .....
*/
private void storeImagesToDB() {
File f = getImagesFile(this);
File[] images = f.listFiles();
int imagecounter = 1;
for (File img: images) {
mDBHlpr.addImageFromPath(img.getPath(),"image" + String.valueOf(imagecounter++));
}
}
/**
* return the directory/folder where the images are stored as a File
* @param context a valid context
* @return the number of images
*/
public static File getImagesFile(Context context) {
if (images_file == null) {
images_file = new File(context.getFilesDir().getPath() + File.separator + IMAGES_DIRECTORY);
if (!images_file.exists()) {
images_file.mkdirs();
}
}
return images_file;
}
/**
* get the number of images
* @return the number of images
*/
public static long getImagesCount() {
File[] files = images_file.listFiles(new FileFilter() {
@Override
public boolean accept(File file) {
return file.isFile();
}
});
return (long) files.length;
}
/**
* Setup/refresh the list of images according to the images folder
* (left ListView)
*/
private void displayList() {
if (mImages == null) {
mImages = new ArrayList<>();
} else {
mImages.clear();
}
mImages.addAll(Arrays.asList(images_file.list()));
if (mAdapter == null) {
mAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, mImages);
mListView01.setAdapter(mAdapter);
} else {
mAdapter.notifyDataSetChanged();
}
}
/**
* Set the image view according to the file
* @param imageName the name of the image (as per the ListView)
*/
private void displayImage(String imageName) {
File img = new File(images_file.getPath() + File.separator + imageName);
if (img.exists()) {
Bitmap bmp = BitmapFactory.decodeFile(img.getAbsolutePath());
mImageView.setImageBitmap(bmp);
}
}
/**
* Set the image view according to the image stored/referred to by the DB
* @param id the id of the respective row in the image table
*/
private void displayDBImage(long id) {
mImageView.setImageBitmap(mDBHlpr.getImage(id));
}
/**
* Setup/refresh the list of images as obtained from the DB (right listview)
*/
private void displayListFromDB() {
mCsr = mDBHlpr.getImageList();
if (mCsrAdapter == null) {
mCsrAdapter = new SimpleCursorAdapter(
this,
android.R.layout.simple_list_item_2,
mCsr,
new String[]{DBHelper.COL_IMAGE_NAME,DBHelper.COL_IMAGE_PATH},
new int[]{android.R.id.text1,android.R.id.text2},
0
);
mListView02.setAdapter(mCsrAdapter);
} else {
mCsrAdapter.swapCursor(mCsr);
}
}
/**
* Load (copy from raw folder to images folder) all images
*/
private void loadRawImages() {
Field[] fields = R.raw.class.getFields();
int resourceID = 0;
String resourceName;
for (Field fld: fields) {
resourceName = fld.getName();
try {
resourceID = fld.getInt(fld);
} catch (IllegalAccessException e) {
e.printStackTrace();
}
Log.d("RAW FLDINFO","name=" + fld.getName() + " ID=" + String.valueOf(resourceID));
copyResourceImageToImages(resourceID,resourceName, true);
}
}
/**
* Copy an image from the raw directory (app/src/main/res/raw directory) to
* the Apps data/data/files/images folder
* @param resourceID ID of the resource
* @param resourceName name of the resource (file name less extension)
* @param throw_exception true if an exception should be thrown
*/
private void copyResourceImageToImages(int resourceID, String resourceName, boolean throw_exception) {
String tag = "CPYRSRCTOIMAGES";
InputStream is = getResources().openRawResource(resourceID);
File of = new File(images_file.getPath() + File.separator + resourceName + ".jpg");
Log.d(tag,"Initiating Copy of File " + of.getName());
int buffer_size = 1024 * 4;
int bytesread = 0;
long bytescopied = 0;
OutputStream os;
byte[] buffer = new byte[buffer_size];
if (!of.exists()) {
try {
of.createNewFile();
} catch (IOException e) {
Log.d(tag,"Error Creating File " + of.getName());
e.printStackTrace();
if (throw_exception) {
throw new RuntimeException("Error Creating Output File" + of.getName());
}
return;
}
}
try {
os = new FileOutputStream(of);
} catch (IOException e) {
Log.d(tag,"Error Creating OutputStream for File " + of.getName());
e.printStackTrace();
if (throw_exception) {
throw new RuntimeException("Error Creating OutputStream for File " + of.getName());
}
return;
}
if (os == null) {
throw new RuntimeException("OutputStream not initialised.");
}
try {
while ((bytesread = is.read(buffer)) > 0 ){
try {
os.write(buffer, 0, bytesread);
} catch (IOException e) {
String msg = "Error Writing to Output File " + of.getName() + " Bytes Copied = " + bytescopied;
Log.d(tag, msg);
e.printStackTrace();
if (throw_exception) {
os.close();
of.delete();
throw new RuntimeException(msg);
}
is.close();
os.close();
of.delete();
return;
}
bytescopied = bytescopied + bytesread;
}
}catch (IOException e) {
String msg = "Error reading Input File " + resourceName + " Bytes Copied = " + bytescopied;
Log.d(tag,"Error Reading Input File " + resourceName);
e.printStackTrace();
if (throw_exception) {
throw new RuntimeException(msg);
}
try {
is.close();
os.close();
of.delete();
} catch (IOException e2) {
e2.printStackTrace();
}
}
Log.d(tag,"File " + of.getName() +" Copied - Bytes Successfully Copied = " + bytescopied);
try {
os.flush();
} catch (IOException e) {
e.printStackTrace();
}
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
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