我正在按照这个教程实现
ViewPager在我的项目中。我已经成功使用静态图片完成了这个过程。现在我想改变它，使得从urls检索图像并在ViewPager中显示。以下是我的代码。
我应该在哪里添加下载图像的方法，如何将其设置到我的
ViewPager中？
任何帮助都将不胜感激。
MainActivity：
public class MainActivity extends AppCompatActivity {
private ArrayList<Integer> images;
private BitmapFactory.Options options;
private ViewPager viewPager;
private View btnNext, btnPrev;
private FragmentStatePagerAdapter adapter;
private LinearLayout thumbnailsContainer;
private final static int[] resourceIDs = new int[]{R.mipmap.a, R.mipmap.b,
R.mipmap.c, R.mipmap.d, R.mipmap.e, R.mipmap.f, R.mipmap.g};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
images = new ArrayList<>();
//find view by id
viewPager = (ViewPager) findViewById(R.id.view_pager);
thumbnailsContainer = (LinearLayout) findViewById(R.id.container);
btnNext = findViewById(R.id.next);
btnPrev = findViewById(R.id.prev);
btnPrev.setOnClickListener(onClickListener(0));
btnNext.setOnClickListener(onClickListener(1));
setImagesData();
// init viewpager adapter and attach
adapter = new ViewPagerAdapter(getSupportFragmentManager(), images);
viewPager.setAdapter(adapter);
inflateThumbnails();
}
private View.OnClickListener onClickListener(final int i) {
return new View.OnClickListener() {
@Override
public void onClick(View v) {
if (i > 0) {
//next page
if (viewPager.getCurrentItem() < viewPager.getAdapter().getCount() - 1) {
viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
}
} else {
//previous page
if (viewPager.getCurrentItem() > 0) {
viewPager.setCurrentItem(viewPager.getCurrentItem() - 1);
}
}
}
};
}
private void setImagesData() {
for (int i = 0; i < resourceIDs.length; i++) {
images.add(resourceIDs[i]);
}
}
private void inflateThumbnails() {
for (int i = 0; i < images.size(); i++) {
View imageLayout = getLayoutInflater().inflate(R.layout.item_image, null);
ImageView imageView = (ImageView) imageLayout.findViewById(R.id.img_thumb);
imageView.setOnClickListener(onChagePageClickListener(i));
options = new BitmapFactory.Options();
options.inSampleSize = 3;
options.inDither = false;
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), images.get(i), options );
imageView.setImageBitmap(bitmap);
//set to image view
imageView.setImageBitmap(bitmap);
//add imageview
thumbnailsContainer.addView(imageLayout);
}
}
private View.OnClickListener onChagePageClickListener(final int i) {
return new View.OnClickListener() {
@Override
public void onClick(View v) {
viewPager.setCurrentItem(i);
}
};
}
}
PageFragment类：
public class PageFragment extends Fragment {
private int imageResource;
private Bitmap bitmap;
public static PageFragment getInstance(int resourceID) {
PageFragment f = new PageFragment();
Bundle args = new Bundle();
args.putInt("image_source", resourceID);
f.setArguments(args);
return f;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
imageResource = getArguments().getInt("image_source");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_page, container, false);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
ImageView imageView = (ImageView) view.findViewById(R.id.image);
BitmapFactory.Options o = new BitmapFactory.Options();
o.inSampleSize = 4;
o.inDither = false;
bitmap = BitmapFactory.decodeResource(getResources(), imageResource, o);
imageView.setImageBitmap(bitmap);
}
@Override
public void onDestroy() {
super.onDestroy();
bitmap.recycle();
bitmap = null;
}
}
ViewPager Adapter class:
public class ViewPagerAdapter extends FragmentStatePagerAdapter {
private List<Integer> images;
public ViewPagerAdapter(FragmentManager fm, List<Integer> imagesList) {
super(fm);
this.images = imagesList;
}
@Override
public Fragment getItem(int position) {
return PageFragment.getInstance(images.get(position));
}
@Override
public int getCount() {
return images.size();
}
}