我是Android的新手，我对Android中的sqlite有所了解。我知道如何从图库中检索图像。任何人都可以帮我将检索到的图像存储在SQL中并检索吗？
我试图存储和检索。我在这里分享我的代码：
我的数据库处理程序类：
public class DatabaseHandler extends SQLiteOpenHelper
{
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "image";
private static final String TABLE_NAME = "store";
private static final String COLUMN_IMAGE = "img";
private static final String COLUMN_ID = "id";
private static final String CREATE_TABLE_IMAGE =
"CREATE TABLE " + TABLE_NAME + " (" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +COLUMN_IMAGE + " BLOB NOT NULL " + ")";
public DatabaseHandler(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(CREATE_TABLE_IMAGE);
Log.i("Table..","Created");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
db.execSQL("DROP TABLE IF EXISTS " + CREATE_TABLE_IMAGE);
onCreate(db);
}
public void insertBitmap(Bitmap bmp)
{
ByteArrayOutputStream out = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, out);
byte[] buffer=out.toByteArray();
SQLiteDatabase db = this.getWritableDatabase();
db.beginTransaction();
ContentValues values;
try
{
values = new ContentValues();
values.put("img",buffer);
db.insert(TABLE_NAME, null, values);
db.setTransactionSuccessful();
Log.i("Image..","Inserted..");
}
catch (SQLiteException e)
{
e.printStackTrace();
}
finally
{
db.endTransaction();
// End the transaction.
db.close();
// Close database
}
}
public Bitmap getBitmap(int id)
{
Bitmap bitmap = null;
SQLiteDatabase db = this.getReadableDatabase();
db.beginTransaction();
try
{
String selectQuery = "SELECT * FROM "+ TABLE_NAME+" WHERE id = " + id;
Cursor cursor = db.rawQuery(selectQuery, null);
int id_value = cursor.getInt(0);
POJO pojo = new POJO(id_value);
Log.i("AUTO ID..",cursor.getString(0));
if(cursor.getCount() >0)
{
while (cursor.moveToNext())
{
byte[] blob = cursor.getBlob(cursor.getColumnIndex(COLUMN_IMAGE));
bitmap= BitmapFactory.decodeByteArray(blob, 0, blob.length);
}
}
db.setTransactionSuccessful();
}
catch (SQLiteException e)
{
e.printStackTrace();
}
finally
{
db.endTransaction();
// End the transaction.
db.close();
// Close database
}
return bitmap;
}
}
我的活动课程：
public class MainActivity extends AppCompatActivity
{
DatabaseHandler dbh;
POJO pojo;
ImageView imageView;
TextView textView;
private static int RESULT_LOAD_IMG = 1;
String picturePath;
int id;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
imageView = (ImageView) findViewById(R.id.image);
textView = (TextView)findViewById(R.id.textView);
textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(i, RESULT_LOAD_IMG);
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
try
{
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
{
if (!Settings.System.canWrite(this) && (requestCode == RESULT_LOAD_IMG && resultCode == RESULT_OK && null != data))
{
requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,
Manifest.permission.READ_EXTERNAL_STORAGE}, 2909);
Uri selectedImage = data.getData();
String[] filePathColumn = {MediaStore.Images.Media.DATA};
Cursor cursor = getContentResolver().query(selectedImage, filePathColumn, null, null, null);
assert cursor != null;
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
picturePath = cursor.getString(columnIndex);
cursor.close();
Bitmap bm = BitmapFactory.decodeFile(picturePath);
Log.i("Hii...", "After Cursor..");
getImage(bm);
}
}
{
Toast.makeText(getApplicationContext(), "Something went wrong", Toast.LENGTH_LONG).show();
}
}
public void getImage(Bitmap bm)
{
Log.i("Hi..","In getImage"); int id = pojo.getId();
dbh.insertBitmap(bm);
imageView.setImageBitmap(dbh.getBitmap(id));
}
}
POJO课程：
public class POJO {
int id;
public POJO (int id1)
{
this.id = id1;
}
public int getId()
{
return id;
}
}
答案 0 :(得分：1)
我建议您将图像的URI（作为字符串）存储到数据库中，而不是将字节直接放入数据库中。
这将更加精确和标准。
更新：
首先将图像的URI作为字符串存储到数据库中，以便以后使用它：
String str = imageUri.toString();
databaseHelper.insert(str);
当您想加载图片时，您可以简单地解码您过去保存的数据库中的URI：
String str = databaseHelper.retrive(someId);
Uri imageUri = Uri.parse(str);
请注意，imageUri是名为Uri的包装中图像的地址。它只是一种呈现Android框架使用的路径和地址的方式。
答案 1 :(得分：1)
我已经对您的代码进行了一些更改，现在它正在按预期工作。
更改了DatabaseHandler课程：
public class DatabaseHandler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "image";
private static final String TABLE_NAME = "store";
private static final String COLUMN_IMAGE = "img";
private static final String COLUMN_ID = "id";
private static final String CREATE_TABLE_IMAGE =
"CREATE TABLE " + TABLE_NAME + " (" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + COLUMN_IMAGE + " BLOB NOT NULL " + ")";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE_IMAGE);
Log.i("Table..", "Created");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + CREATE_TABLE_IMAGE);
onCreate(db);
}
public long insertBitmap(Bitmap bmp) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, out);
byte[] buffer = out.toByteArray();
SQLiteDatabase db = this.getWritableDatabase();
db.beginTransaction();
ContentValues values;
long id = 0;
try {
values = new ContentValues();
values.put("img", buffer);
id = db.insert(TABLE_NAME, null, values);
db.setTransactionSuccessful();
Log.i("Image..", "Inserted..");
} catch (SQLiteException e) {
e.printStackTrace();
} finally {
db.endTransaction();
// End the transaction.
db.close();
// Close database
}
return id;
}
public Bitmap getBitmap(int id) {
Bitmap bitmap = null;
SQLiteDatabase db = this.getReadableDatabase();
db.beginTransaction();
try {
String selectQuery = "SELECT * FROM " + TABLE_NAME + " WHERE id = " + id;
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.getCount() > 0) {
while (cursor.moveToNext()) {
byte[] blob = cursor.getBlob(cursor.getColumnIndex(COLUMN_IMAGE));
bitmap = BitmapFactory.decodeByteArray(blob, 0, blob.length);
}
}
db.setTransactionSuccessful();
} catch (SQLiteException e) {
e.printStackTrace();
} finally {
db.endTransaction();
// End the transaction.
db.close();
// Close database
}
return bitmap;
}
}
更改了MainActivity课程：
public class MainActivity extends AppCompatActivity
{
DatabaseHandler dbh;
POJO pojo;
ImageView imageView;
TextView textView;
private static int RESULT_LOAD_IMG = 1;
String picturePath;
int id;
public final int REQUEST_CODE_FOR_PERMISSIONS = 654;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imageView = (ImageView) findViewById(R.id.image);
textView = (TextView)findViewById(R.id.textView);
textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(i, RESULT_LOAD_IMG);
}
});
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED &&
ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(
this,
new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,
Manifest.permission.READ_EXTERNAL_STORAGE},
REQUEST_CODE_FOR_PERMISSIONS);
}
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == RESULT_LOAD_IMG){
Uri selectedImage = data.getData();
String[] filePathColumn = {MediaStore.Images.Media.DATA};
Cursor cursor = getContentResolver().query(selectedImage, filePathColumn, null, null, null);
assert cursor != null;
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
picturePath = cursor.getString(columnIndex);
cursor.close();
Bitmap bm = BitmapFactory.decodeFile(picturePath);
Log.i("Hii...", "After Cursor..");
getImage(bm);
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if(requestCode == REQUEST_CODE_FOR_PERMISSIONS){
//You need to handle permission results, if user didn't allow them.
}
}
public void getImage(Bitmap bm) {
Log.i("Hi..", "In getImage "+bm);
dbh = new DatabaseHandler(this);
int id = (int) dbh.insertBitmap(bm);
imageView.setImageBitmap(dbh.getBitmap(id));
}
}
我在HTC marshmallow设备上测试了这段代码，它运行正常。当我第一次安装这个应用程序时，它会询问我的权限，并且我已经允许这两个权限。