有必要下载图像(在 SD 卡上)然后使用它吗?如果没有,该怎么做? 我在 PagerView 中有图像存储和图像显示(图像从互联网加载)。我需要从 PagerView 中选择一张图片并将其放在背景(壁纸)上。我无法在 ImagePagerActivity 中添加按钮以将图像添加到背景。错误:E/AndroidRuntime(14608):java.lang.RuntimeException:无法启动活动 ComponentInfo{down.load.ascetix/down.load.ascetix.ImagePagerActivity}:java.lang.ClassCastException:down.load.ascetix.ImagePagerActivity。
ImagePager活动:
public class ImagePagerActivity extends BaseActivity {
private ViewPager pager;
private DisplayImageOptions options;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.ac_image_pager);
Bundle bundle = getIntent().getExtras();
String[] imageUrls = bundle.getStringArray(Extra.IMAGES);
int pagerPosition = bundle.getInt(Extra.IMAGE_POSITION, 0);
options = new DisplayImageOptions.Builder()
.showImageForEmptyUri(R.drawable.image_for_empty_url)
.cacheOnDisc()
.imageScaleType(ImageScaleType.EXACT)
.build();
pager = (ViewPager) findViewById(R.id.pager);
pager.setAdapter(new ImagePagerAdapter(imageUrls));
pager.setCurrentItem(pagerPosition);
}
@Override
protected void onStop() {
imageLoader.stop();
super.onStop();
}
private class ImagePagerAdapter extends PagerAdapter {
private String[] images;
private LayoutInflater inflater;
ImagePagerAdapter(String[] images) {
this.images = images;
inflater = getLayoutInflater();
}
public void destroyItem(View container, int position, Object object) {
((ViewPager) container).removeView((View) object);
}
public void finishUpdate(View container) {
}
public int getCount() {
return images.length;
}
public Object instantiateItem(View view, int position) {
final FrameLayout imageLayout = (FrameLayout) inflater.inflate(R.layout.item_pager_image, null);
final ImageView imageView = (ImageView) imageLayout.findViewById(R.id.image);
final ProgressBar spinner = (ProgressBar) imageLayout.findViewById(R.id.loading);
imageLoader.displayImage(images[position], imageView, options, new ImageLoadingListener() {
public void onLoadingStarted() {
spinner.setVisibility(View.VISIBLE);
}
public void onLoadingFailed(FailReason failReason) {
String message = null;
switch (failReason) {
case IO_ERROR:
message = "Input/Output error";
break;
case OUT_OF_MEMORY:
message = "Out Of Memory error";
break;
case UNKNOWN:
message = "Unknown error";
break;
}
Toast.makeText(ImagePagerActivity.this, message, Toast.LENGTH_SHORT).show();
spinner.setVisibility(View.GONE);
imageView.setImageResource(android.R.drawable.ic_delete);
}
public void onLoadingComplete() {
spinner.setVisibility(View.GONE);
Animation anim = AnimationUtils.loadAnimation(ImagePagerActivity.this, R.anim.fade_in);
imageView.setAnimation(anim);
anim.start();
}
public void onLoadingCancelled() {
// Do nothing
}
});
((ViewPager) view).addView(imageLayout, 0);
return imageLayout;
}
public boolean isViewFromObject(View view, Object object) {
return view.equals(object);
}
public void restoreState(Parcelable state, ClassLoader loader) {
}
public Parcelable saveState() {
return null;
}
public void startUpdate(View container) {
}
}
}
我的 .xml 文件:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="1dip">
<ImageView
android:id="@+id/image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:adjustViewBounds="true" />
<ProgressBar
android:id="@+id/loading"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:visibility="gone" />
</FrameLayout>
谢谢。