将当前图像保存到sqlite android

Question

我正在制作一个供读书者使用的android应用程序，接下来有3个按钮，上一个和书签（单页）。当用户单击下一个/上一个按钮时，图像会更改，问题是如何将当前图像（显示给用户）保存到sqlite数据库？这是我的MainActivity Java文件：

package com.example.book;
import android.annotation.SuppressLint;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import java.io.ByteArrayOutputStream;

public class MainActivity extends AppCompatActivity {
    byte[] img1;
    Bitmap b;
    MyDataBase myDataBase;
    SQLiteDatabase database;
    Cursor c;
    private int passed =0;


    private int currentImage = 0;
    private ImageView viewImage;

    int[] images = {R.drawable.f1,R.drawable.f2,R.drawable.f3,R.drawable.f4,R.drawable.f5,
                    R.drawable.f6,R.drawable.f7,R.drawable.f8,R.drawable.f9,R.drawable.f10};


    @SuppressLint("WrongThread")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        try{
            myDataBase=new MyDataBase(getApplicationContext(),"imagedata",null,1);
        }
        catch (Exception e){
            e.printStackTrace();
        }


        viewImage =  findViewById(R.id.viewImage);

        Button next = findViewById(R.id.next);
        Button previous = findViewById(R.id.previous);
        Button bookmark = findViewById(R.id.save);

        next.setOnClickListener(nextImage);
        previous.setOnClickListener(previousImage);
        bookmark.setOnClickListener(save);

    }

    View.OnClickListener nextImage = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(currentImage == (images.length-1)){
                viewImage.setImageResource(images[currentImage]);
            }
            else
            {
                currentImage++;
                currentImage = currentImage % images.length;
                //a%b = a -floor(a/b) *b
                viewImage.setImageResource(images[currentImage]);
            }
        }
    };

    View.OnClickListener previousImage = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(currentImage==0){
                viewImage.setImageResource(images[currentImage]);
            }
            else{
                currentImage--; // if current image is 6
                currentImage = (currentImage+images.length) %images.length;
                //(5+10) % 10 =   15%10 = 5  5th image is loaded

                viewImage.setImageResource(images[currentImage]);

            }

        }
    };


    View.OnClickListener save = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //get resource
            //Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.f1);
            //what to do here? how to save current image ? to sqlite?
            Bitmap bitmap =((BitmapDrawable)viewImage.getDrawable().);

            ByteArrayOutputStream bos=new ByteArrayOutputStream();

            bitmap.compress(Bitmap.CompressFormat.PNG, 100, bos);

            byte[] img=bos.toByteArray();
            database=myDataBase.getWritableDatabase();

// content values is used to create empty set of values using the default initial size
            ContentValues cv=new ContentValues();
            cv.put("image", img);
            database.insert("tableimage", null, cv);


        }
    };


}

在此行做什么？提取当前图像并将其存储在sqlite中？

Bitmap bitmap =((BitmapDrawable)viewImage.getDrawable().); ???

MyDatabase.java文件也是：

package com.example.book;

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

class MyDataBase extends SQLiteOpenHelper {

    public MyDataBase(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {

        super(context, name, factory, version);

        // TODO Auto-generated constructor stub

    }


    public void onCreate(SQLiteDatabase db) {

        // TODO Auto-generated method stub

        db.execSQL("create table tableimage (image blob , id int PRIMARY KEY);");

    }


    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        // TODO Auto-generated method stub


    }

}

如果我的方向错误，请帮帮我。