保存书的最后一页并在打开书时加载?

Save the last page of the book and load when the book is opened?

我正在开发一个将有一些书的应用程序,我不知道如何保存书本打开的最后一页并在打开书本时打开,即使应用程序关闭也是如此。我不使用片段,只使用 CustomSwipeAdapterImageViewTouchViewPagerViewPager.

一切正常,我只需要这个,其实在MainActivity我可以保存当前位置但是我不知道如何设置保存到打开书时显示之前的最后一页该应用已关闭。

谢谢。

public class CustomSwipeAdapter1 extends PagerAdapter{    

private int[] pagesBookOne = {R.drawable.pageone, R.drawable.pagetwo, R.drawable.pagethree};
    private Context context;
    private LayoutInflater layoutInflater;
    private ViewPager viewPager;

public CustomSwipeAdapter1(Context context){

        this.context = context;

    }


    @Override
    public int getCount() {
        return paginasLivroUm.length;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return (view == (LinearLayout) object);
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {

        layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View item_view = layoutInflater.inflate(R.layout.swipe_layout, container, false);
        ImageViewTouch imageViewTouch = item_view.findViewById(R.id.imageviewtouch_xml);
        imageViewTouch.setImageResource(paginasLivroUm[position]);

        imageViewTouch.setDisplayType(ImageViewTouchBase.DisplayType.FIT_TO_SCREEN);

        container.addView(item_view);
        return item_view;

    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((LinearLayout) object);
        //super.destroyItem(container, position, object);

    }

}

==========================================================


import android.os.PersistableBundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;


public class LivroUmActivity extends AppCompatActivity {


    private ViewPager viewPager1;
    private CustomSwipeAdapter1 adapter1;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_livro_um);


        viewPager1 = findViewById(R.id.viewpager1_xml);
        adapter1 = new CustomSwipeAdapter1(this);

        viewPager1.setAdapter(adapter1);



    }

    @Override
    protected void onDestroy() {

        positionSaved  = viewPager1.getCurrentItem();

       //Here I can save the position, just don't know how to set on the viewpager.
        super.onDestroy();
    }


}

==========================================================


import android.content.Context;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

import it.sephiroth.android.library.imagezoom.ImageViewTouch;
import it.sephiroth.android.library.imagezoom.ImageViewTouchBase;


public class ImageViewTouchViewPager extends ViewPager{

    private static final String TAG = "ImageViewTouchViewPager";
    public static final String VIEW_PAGER_OBJECT_TAG = "image#";

    private int previousPosition;

    private OnPageSelectedListener onPageSelectedListener;

    public ImageViewTouchViewPager(Context context) {
        super(context);
        init();
    }

    public ImageViewTouchViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public void setOnPageSelectedListener(OnPageSelectedListener listener) {
        onPageSelectedListener = listener;
    }

    @Override
    protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {
        if (v instanceof ImageViewTouch) {
            return ((ImageViewTouch) v).canScroll(dx);
        } else {
            return super.canScroll(v, checkV, dx, x, y);
        }
    }

    public interface OnPageSelectedListener {

        public void onPageSelected(int position);

    }

    private void init() {
        previousPosition = getCurrentItem();

        setOnPageChangeListener(new SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                if (onPageSelectedListener != null) {
                    onPageSelectedListener.onPageSelected(position);
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {
                if (state == SCROLL_STATE_SETTLING && previousPosition != getCurrentItem()) {
                    try {
                        ImageViewTouch imageViewTouch = (ImageViewTouch)
                                findViewWithTag(VIEW_PAGER_OBJECT_TAG + getCurrentItem());
                        if (imageViewTouch != null) {
                            imageViewTouch.zoomTo(1f, 300);
                        }

                        previousPosition = getCurrentItem();
                    } catch (ClassCastException ex) {
                        Log.e(TAG, "This view pager should have only ImageViewTouch as a children.", ex);
                    }
                }
            }
        });
    }
}

由于应用程序关闭并再次打开,您需要将页码保存在持久存储中。由于它只是一个数字,您可以使用 SharedPreference。

所以在 SharedPreference 中有一个键,例如 "pageNumber"。并且每次加载新页面时,将页码保存到"pageNumber"。这样您就不必担心在应用程序关闭之前保存最后一个页码。

再次打开应用程序时,检查 "pageNumber" 并加载它。

您可以参考:

  • 关闭应用程序时使用共享首选项保存书的最后一页
  • 当您打开应用程序时,您可以获取最后一页并设置最后一页的位置:

viewPager.setCurrentItem(/** lastpage get from Shared Preferences */);

希望对您的问题有所帮助!