Question

我想插入图像，删除图像并从SQLite数据库中检索所有图像。我正在创建数据库，代码如下所示。

但是如何在MainActivity中调用这些方法？

public class Imagehelper extends SQLiteOpenHelper {     
        private static final String DATABASE_NAME="abhi.db";
        private static final int SCHEMA_VERSION=1; 

        public Imagehelper(Context context) {
            super(context, DATABASE_NAME, null, SCHEMA_VERSION);
            }
        @Override
        public void onCreate(SQLiteDatabase db) {
            // TODO Auto-generated method stub          
            db.execSQL("CREATE TABLE Image(_id INTEGER PRIMARY KEY AUTOINCREMENT,imageblob BLOB);");
            }
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        }       
        public Cursor getAll() {                
            return(getReadableDatabase().rawQuery("SELECT imageblob FROM Image",null));
        }   
        public void insert(byte[] bytes)
        {
            ContentValues cv=new ContentValues();

            cv.put("imageblob",bytes);
            Log.e("inserted", "inserted");
            getWritableDatabase().insert("Image","imageblob",cv);
            System.out.println(":vlfkv: " +cv.size());
        }
        public byte[] getImage(Cursor c)
          {
              return(c.getBlob(1));
          }

        public void deletePhoto(String id) {

            SQLiteDatabase database = this.getWritableDatabase();    
            String deleteQuery = "DELETE FROM  Image where _id='"+ id +"'";
            Log.d("query",deleteQuery);     
            database.execSQL(deleteQuery);
        }
    }

Answer 1

您的活动中需要有Imagehelper的实例：

Imagehelper mImageHelper = new Imagehelper();

// and then you can access your methods ...
mImageHelper.insert(yourValue);
mImageHelper.get(yourValue);
mImageHelper.deletePhoto(yourValue);

我建议您按照Android的一些dabatase教程：

http://www.vogella.com/articles/AndroidSQLite/article.html

http://www.androidhive.info/2011/11/android-sqlite-database-tutorial/

Answer 2

使用此代码。其中image是字节数组。将所有图像作为byte[]代码获取已经编写

Bitmap bmp = BitmapFactory.decodeByteArray(image, 0, image.length);

Answer 3

您尚未在 getImage 方法中调用选择查询。所以看下面的功能。

public byte[] getImage(
{
   Cursor c = database.rawQuery("SELECT imageblob FROM Image",null);               
   return(c.getBlob(1));
}

如何从mainActivity中的sqlite中检索所有存储的图像？

3 个答案: