我如何解码图像？从sqlite中检索图像

Question

我如何从sql lite中检索图像？这个代码适用于小尺寸图像，当我使用重jpg图像不显示我该怎么办？我发现解决方案解码图像，但我放置代码？下面是我的完整源代码

  public class SQLiteDemoActivity extends Activity {




  ArrayList<Contact> imageArry = new ArrayList<Contact>();
  ContactImageAdapter adapter;
  Button BrowseButton;
 Button BrowseButton2;
 DataBaseHandler db;





   ByteArrayOutputStream stream = new ByteArrayOutputStream();
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);

   db = new DataBaseHandler(this);
   //get image from drawable




   BrowseButton=(Button)findViewById(R.id.BrowseButton);
   BrowseButton2=(Button)findViewById(R.id.BrowseButton2);

   adapter = new ContactImageAdapter(this, R.layout.screen_list,    imageArry);

   BrowseButton.setOnClickListener(new View.OnClickListener() {

    @Override
   public void onClick(View v) {



    Bitmap image = BitmapFactory.decodeResource(getResources(),R.drawable.my);


    image.compress(Bitmap.CompressFormat.JPEG, 100, stream);
    byte[] imageInByte = stream.toByteArray();

    Log.d("Insert: ", "Inserting ..");
    db.addContact(new Contact("FaceBook", imageInByte));
    //display main List view bcard and contact name

    //Reading all contacts from database

  //        

   }
   });

     BrowseButton2.setOnClickListener(new View.OnClickListener() {

   @Override
   public void onClick(View v) {


    List<Contact> contacts = db.getAllContacts();
    for (Contact cn : contacts) {




    String log = "ID:" + cn.getID() + " Name: " + cn.getName()      + " ,Image: " +  
     cn.getImage();


    //Writing Contacts to log
    Log.d("Result: ", log);
    //add contacts data in arrayList
    imageArry.add(cn);

    }

    ListView dataList = (ListView) findViewById(R.id.list);
    dataList.setAdapter(adapter);

    try {
        stream.close();
        stream = null;
    } catch (IOException e) {

        e.printStackTrace();
    }

  }
    });

  }








        public class Contact {

// private variables
int _id;
String _name;
byte[] _image;

// Empty constructor
public Contact() {

}

// constructor
public Contact(int keyId, String name, byte[] image) {
this._id = keyId;
this._name = name;
this._image = image;

}

// constructor
public Contact(String contactID, String name, byte[] image) {
this._name = name;
this._image = image;

}

// constructor
public Contact(String name, byte[] image) {
this._name = name;
this._image = image;
}

// getting ID
public int getID() {
return this._id;
}

// setting id
public void setID(int keyId) {
this._id = keyId;
}

// getting name
public String getName() {
return this._name;
}

// setting name
public void setName(String name) {
this._name = name;
}

// getting phone number
public byte[] getImage() {
return this._image;
}

// setting phone number
public void setImage(byte[] image) {
this._image = image;
}
}





       public class ContactImageAdapter extends ArrayAdapter<Contact>{
      Context context;
     int layoutResourceId;
   //BcardImage data[] = null;
    ArrayList<Contact> data=new ArrayList<Contact>();
    public ContactImageAdapter(Context context, int layoutResourceId,  
    ArrayList<Contact>  
      data) {
   super(context, layoutResourceId, data);
  this.layoutResourceId = layoutResourceId;
   this.context = context;
   this.data = data;
   }

    @Override
   public View getView(int position, View convertView, ViewGroup parent) {
   View row = convertView;
   ImageHolder holder = null;
   if(row == null)
   {
    LayoutInflater inflater = ((Activity)context).getLayoutInflater();
   row = inflater.inflate(layoutResourceId, parent, false);
   holder = new ImageHolder();
   holder.txtTitle = (TextView)row.findViewById(R.id.txtTitle);
   holder.imgIcon = (ImageView)row.findViewById(R.id.imgIcon);
   row.setTag(holder);
    }
   else
  {
   holder = (ImageHolder)row.getTag();
    }
   Contact picture = data.get(position);
   holder.txtTitle.setText("facebook");
   //convert byte to bitmap take from contact class
    byte[] outImage=picture._image;
   ByteArrayInputStream imageStream = new ByteArrayInputStream(outImage);
   Bitmap theImage = BitmapFactory.decodeStream(imageStream);
    holder.imgIcon.setImageBitmap(theImage);
   return row;
    }
   static class ImageHolder
   {
  ImageView imgIcon;
  TextView txtTitle;
   }
  }









        import java.util.ArrayList;
       import java.util.List;

          import android.content.ContentValues;
      import android.content.Context;
     import android.database.Cursor;
      import android.database.sqlite.SQLiteDatabase;
       import android.database.sqlite.SQLiteOpenHelper;

       public class DataBaseHandler extends SQLiteOpenHelper {

     //All Static variables
      //Database Version
      private static final int DATABASE_VERSION = 1;

      //Database Name
       private static final String DATABASE_NAME = "imagedb";

     //Contacts table name
     private static final String TABLE_CONTACTS = "contacts";

   //Contacts Table Columns names
     private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
   private static final String KEY_IMAGE = "image";

    public DataBaseHandler(Context context) {
     super(context, DATABASE_NAME, null, DATABASE_VERSION);
     }

   //Creating Tables
     @Override
       public void onCreate(SQLiteDatabase db) {
    String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
    + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
    + KEY_IMAGE + " BLOB" + ")";
   db.execSQL(CREATE_CONTACTS_TABLE);
       }

    //Upgrading database
      @Override
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    //Drop older table if existed
     db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);

   //Create tables again
    onCreate(db);
     }

     /**
     * All CRUD(Create, Read, Update, Delete) Operations
       */

      public// Adding new contact
     void addContact(Contact contact) {
     SQLiteDatabase db = this.getWritableDatabase();

      ContentValues values = new ContentValues();
   values.put(KEY_NAME, contact._name); // Contact Name
     values.put(KEY_IMAGE, contact._image); // Contact Phone

    //Inserting Row
    db.insert(TABLE_CONTACTS, null, values);
    db.close(); // Closing database connection
   }

      //Getting single contact
     Contact getContact(int id) {
     SQLiteDatabase db = this.getReadableDatabase();

   Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,
      KEY_NAME, KEY_IMAGE }, KEY_ID + "=?",
   new String[] { String.valueOf(id) }, null, null, null, null);
    if (cursor != null)
   cursor.moveToFirst();

   Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),
   cursor.getString(1), cursor.getBlob(1));

    //return contact
     return contact;

     }

    //Getting All Contacts
      public List<Contact> getAllContacts() {
    List<Contact> contactList = new ArrayList<Contact>();
   //Select All Query
    String selectQuery = "SELECT * FROM contacts ORDER BY name";

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);
  //looping through all rows and adding to list
    if (cursor.moveToFirst()) {
   do {
  Contact contact = new Contact();
  contact.setID(Integer.parseInt(cursor.getString(0)));
  contact.setName(cursor.getString(1));
  contact.setImage(cursor.getBlob(2));
  //Adding contact to list
  contactList.add(contact);
  } while (cursor.moveToNext());
  }
     //close inserting data from database
    db.close();
     //return contact list
     return contactList;

      }

   //Updating single contact
    public int updateContact(Contact contact) {
     SQLiteDatabase db = this.getWritableDatabase();

   ContentValues values = new ContentValues();
    values.put(KEY_NAME, contact.getName());
    values.put(KEY_IMAGE, contact.getImage());

//updating row
   return db.update(TABLE_CONTACTS, values, KEY_ID + " = ?",
  new String[] { String.valueOf(contact.getID()) });

      }

 //Deleting single contact
   public void deleteContact(Contact contact) {
  SQLiteDatabase db = this.getWritableDatabase();
   db.delete(TABLE_CONTACTS, KEY_ID + " = ?",
  new String[] { String.valueOf(contact.getID()) });
    db.close();
 }

 //Getting contacts Count
     public int getContactsCount() {
   String countQuery = "SELECT * FROM " + TABLE_CONTACTS;
 SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(countQuery, null);
     cursor.close();

  //return count
   return cursor.getCount();
  }






    <------ from where i used this function------------->




              private Bitmap decodeFile(File f) {
        try {
            // decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            BitmapFactory.decodeStream(new FileInputStream(f), null, o);

            // Find the correct scale value. It should be the power of 2.
            final int REQUIRED_SIZE = 70;
            int width_tmp = o.outWidth, height_tmp = o.outHeight;
            int scale = 1;
            while (true) {
                if (width_tmp / 2 < REQUIRED_SIZE || height_tmp / 2 <  
          REQUIRED_SIZE)
                    break;
                width_tmp /= 2;
                height_tmp /= 2;
                scale++;
            }

            // decode with inSampleSize
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inSampleSize = scale;
            return BitmapFactory.decodeStream(new FileInputStream(f), null,  
    o2);
        }
        catch (FileNotFoundException e) {
        }
        return null;
    }

Answer 1

在数据库中使用blob列并保存base64编码的图像，然后您可以毫无困难地解码它，只有在图像大小很大的情况下才可以在内存堆中运行。

Answer 2

我认为正确的方法是将图像作为文件保存在内部存储中，并将路径存储在sqlite中。但是您必须记住内部缓存是有限的。因此，如果您要存储大量图像，则必须使用WhatsApp之类的外部存储。
For internal storage limit.

For save and read image from storage.

Internal vs External storage