以下代码是从显示为SD卡的数据库中下载图像。预览时显示图像。第一张图片显示得很完美，但是从下一张图片开始，它显示为空白并从SD卡中加载图像，但是从SD卡开始，它没有直接下载图像显示图像。
的java
public class ImageGallery extends Activity {
Bundle bundle;
String catid, temp, responseJson;
JSONObject json;
ImageView imageViewPager;
// for parsing
JSONObject o1, o2;
JSONArray a1, a2;
int k;
Boolean toggleTopBar;
ArrayList<String> imageThumbnails;
ArrayList<String> imageFull;
public static int imagePosition=0;
SubsamplingScaleImageView imageView, imageViewPreview, fullImage ;
ImageView thumb1, back;
private LinearLayout thumb2;
RelativeLayout topLayout, stripeView;
RelativeLayout thumbnailButtons;
FrameLayout gridFrame;
public ImageLoader imageLoader;
//SharedPreferences data
SharedPreferences s1;
SharedPreferences.Editor editor;
int swipeCounter;
ParsingForFinalImages parsingObject;
int position_grid;
SharedPreferences p;
Bitmap bm;
int numOfImagesInsidee;
LinearLayout backLinLayout;
public static boolean isThumb2=false;
public static boolean isThumb1=false;
public static ViewPager viewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_image_gallery);
//isThumb2=false;
toggleTopBar = false;
//position_grid=getIntent().getExtras().getInt("position");
thumbnailButtons = (RelativeLayout)findViewById(R.id.thumbnailButtons);
topLayout = (RelativeLayout)findViewById(R.id.topLayout);
//fullImage = (SubsamplingScaleImageView)findViewById(R.id.fullimage);
backLinLayout = (LinearLayout)findViewById(R.id.lin_back);
backLinLayout.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent io = new Intent(getBaseContext(), MainActivity.class);
// clear the previous activity and start a new task
// System.gc();
// io.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(io);
finish();
}
});
ConnectionDetector cd = new ConnectionDetector(getBaseContext());
Boolean isInternetPresent = cd.isConnectingToInternet();
thumb1 = (ImageView)findViewById(R.id.thumb1);
thumb2 = (LinearLayout)findViewById(R.id.thumb2);
stripeView = (RelativeLayout)findViewById(R.id.stripeView) ;
gridFrame = (FrameLayout)findViewById(R.id.gridFrame);
thumb1.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View view) {
stripeView.setVisibility(View.GONE);
gridFrame.setVisibility(View.VISIBLE);
viewPager.setVisibility(View.GONE);
//fullImage.setVisibility(View.GONE);
thumb1.setClickable(false);
isThumb1=true;
isThumb2=false;
Log.i("Thumb Position 1",""+ImageGallery.imagePosition);
viewPager.removeAllViews();
Fragment newFragment = new GridFragment2();
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.gridFrame, newFragment).commit();
}
});
thumb2.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View view) {
// stripeView.setVisibility(View.VISIBLE);
stripeView.setVisibility(View.GONE);
gridFrame.setVisibility(View.VISIBLE);
viewPager.setVisibility(View.GONE);
// fullImage.setVisibility(View.GONE);
thumb1.setClickable(true);
isThumb2=true;
isThumb1=false;
Log.i("Thumb Position 2",""+ImageGallery.imagePosition);
viewPager.removeAllViews();
Fragment newFragment = new ImageStripeFragment();
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.gridFrame, newFragment).commit();
}
});
// allow networking on main thread
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
/*bundle = getIntent().getExtras();
catid = bundle.getString("catid");*/
// Toast.makeText(getBaseContext(), catid, Toast.LENGTH_LONG).show();
// making json using the catalogue id we got
p = getSharedPreferences("gridData", Context.MODE_APPEND);
catid = p.getString("SelectedCatalogueIdFromGrid1", "");
int clickedListPos = p.getInt("clickedPosition", 0);
imageViewPreview = (SubsamplingScaleImageView)findViewById(R.id.preview);
imageThumbnails = new ArrayList<String>();
imageFull = new ArrayList<String>();
s1 = this.getSharedPreferences("data", Context.MODE_APPEND);
editor = s1.edit();
Log.d("catidfnl", catid);
numOfImagesInsidee = p.getInt("numberOfItemsSelectedFromGrid1", 0);
Log.d("blingbling2", String.valueOf(numOfImagesInsidee));
// adding downloaded images to arraylist
for(int m=0;m<numOfImagesInsidee;m++){
imageThumbnails.add(Environment.getExternalStorageDirectory()+"/"+"thumbImage" + catid + m+".png");
imageFull.add(Environment.getExternalStorageDirectory()+"/"+"fullImage" + catid + m+".png");
// imageFull.add("file://" + Environment.getExternalStorageDirectory() + "/" + "fullImage32.png");
}
viewPager = (ViewPager) findViewById(R.id.pager);
ImagePagerAdapter adapter = new ImagePagerAdapter();
viewPager.setAdapter(adapter);
SubsamplingScaleImageView fullImage = new SubsamplingScaleImageView(ImageGallery.this);
// code to display image in a horizontal strip starts here
LinearLayout layout = (LinearLayout) findViewById(R.id.linear);
for (int i = 0; i < imageThumbnails.size(); i++) {
imageView = new SubsamplingScaleImageView(this);
imageView.setId(i);
imageView.setPadding(2, 2, 2, 2);
// Picasso.with(this).load("file://"+imageThumbnails.get(i)).into(imageView);
// imageView.setScaleType(ImageView.ScaleType.FIT_XY);
layout.addView(imageView);
ViewGroup.LayoutParams params = imageView.getLayoutParams();
params.width = 200;
params.height = 200;
imageView.setLayoutParams(params);
imageView.setZoomEnabled(false);
imageView.setDoubleTapZoomScale(0);
imageView.setImage(ImageSource.uri(imageThumbnails.get(0)));
imageView.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View view) {
imageView.setZoomEnabled(false);
imageViewPreview.setImage(ImageSource.uri(imageFull.get(view.getId())));
imageView.recycle();
imageViewPreview.recycle();
}
});
}
// code to display image in a horizontal strip ends here
imageViewPreview.setZoomEnabled(false);
/*imageViewPreview.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View view) {
imageViewPreview.setZoomEnabled(false);
stripeView.setVisibility(View.GONE);
gridFrame.setVisibility(View.GONE);
viewPager.setVisibility(View.VISIBLE);
}
});*/
imageViewPreview.setOnClickListener(new DoubleClickListener() {
@Override
public void onSingleClick(View v) {
Log.d("yo click", "single");
}
@Override
public void onDoubleClick(View v) {
Log.d("yo click", "double");
}
});
}
public abstract class DoubleClickListener implements View.OnClickListener {
private static final long DOUBLE_CLICK_TIME_DELTA = 300;//milliseconds
long lastClickTime = 0;
@Override
public void onClick(View v) {
long clickTime = System.currentTimeMillis();
if (clickTime - lastClickTime < DOUBLE_CLICK_TIME_DELTA){
onDoubleClick(v);
} else {
onSingleClick(v);
}
lastClickTime = clickTime;
}
public abstract void onSingleClick(View v);
public abstract void onDoubleClick(View v);
}
// @Override
// public void onBackPressed() {
// Intent io = new Intent(getBaseContext(), MainActivity.class);
// // clear the previous activity and start a new task
// super.onBackPressed();
// finish();
// // System.gc();
// // io.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
// startActivity(io);
// }
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_image_gallery, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private class ImagePagerAdapter extends PagerAdapter {
/* private int[] mImages = new int[] {
R.drawable.scroll3,
R.drawable.scroll1,
R.drawable.scroll2,
R.drawable.scroll4
};*/
/* private String[] description=new String[]
{
"One","two","three","four"
};
*/
@Override
public int getCount() {
Log.i("Image List Size", "" + imageFull.size());
return imageFull.size();
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == ((SubsamplingScaleImageView) object);
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
Context context = ImageGallery.this;
// ImageLoader loader = new ImageLoader(context, 1);
// loader.DisplayImage(ImageSource.uri(imageFull.get(imagePosition)),imageView,imagePosition,new ProgressDialog(context));
SubsamplingScaleImageView fullImage = new SubsamplingScaleImageView(ImageGallery.this);
// for placeholder
// fullImage.setImage(ImageSource.resource(R.drawable.tan2x));
if(!GridFragment2.isSelectedGrid2&&!ImageStripeFragment.isImageStripe) {
imagePosition = position;
fullImage.setImage(ImageSource.uri(imageFull.get(imagePosition)));
}
/* else if(!ImageStripeFragment.isImageStripe)
{
imagePosition = position;
fullImage.setImage(ImageSource.uri(imageFull.get(imagePosition)));
}
else if(ImageStripeFragment.isImageStripe)
{
position=imagePosition;
viewPager.setCurrentItem(imagePosition);
fullImage.setImage(ImageSource.uri(imageFull.get(position)));
}*/
else
{
position=imagePosition;
viewPager.setCurrentItem(imagePosition);
fullImage.setImage(ImageSource.uri(imageFull.get(position)));
//viewPager.removeAllViews();
}
// ImageView imageViewPager = new ImageView(context);
// ImageView imageViewPager = new ImageView(getApplicationContext());
// SubsamplingScaleImageView fullImage = new SubsamplingScaleImageView(ImageGallery.this);
GridFragment2.isSelectedGrid2=false;
ImageStripeFragment.isImageStripe=false;
// Log.i("Image Resource", "" + ImageSource.uri(imageFull.get(position)));
// imageViewPager.setImageBitmap(BitmapFactory.decodeFile(imageFull.get(position)));
// imageViewPager.setImageBitmap(myBitmap);
// fullImage.setImage(ImageSource.bitmap(bmImg));
//imageView.setImageResource(Integer.parseInt(imageFull.get(position)));
/*int padding = context.getResources().getDimensionPixelSize(
R.dimen.padding_medium);
imageView.setPadding(padding, padding, padding, padding);*/
/*imageView.setScaleType(ImageView.ScaleType.CENTER);
imageView.setImageResource(Integer.parseInt(imageFull.get(position)));
if(position==3)
{
}*/
// Log.i("Image Position",""+position);
/*text.setText(description[position]);
Log.i("Text Position",""+position);*/
/*switch(position)
{
case 0:
String pos=String.valueOf(position);
text.setText(pos);
break;
case 1:
String pos1=String.valueOf(position);
text.setText(pos1);
break;
case 2:
String pos2=String.valueOf(position);
text.setText(pos2);
break;
case 3:
String pos3=String.valueOf(position);
text.setText(pos3);
break;
}*/
fullImage.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View view) {
if (toggleTopBar == false) {
// thumbnailButtons.setVisibility(View.GONE);
thumbnailButtons.animate()
.translationY(-2000)
.setDuration(1000)
.start();
toggleTopBar = true;
} else if (toggleTopBar == true) {
// thumbnailButtons.setVisibility(View.VISIBLE);
thumbnailButtons.animate()
.translationY(0)
.setDuration(1000)
.start();
toggleTopBar = false;
}
}
});
((ViewPager) container).addView(fullImage, 0);
return fullImage;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
((ViewPager) container).removeView((SubsamplingScaleImageView) object);
}
/* @Override
public void destroyItem(View collection, int position, Object o) {
Log.d("DESTROY", "destroying view at position " + position);
View view = (View) o;
((ViewPager) collection).removeView(view);
view = null;
}*/
}
@Override
public void onBackPressed() {
// TODO Auto-generated method stub
super.onBackPressed();
Intent intent = new Intent(getApplicationContext(), MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
finish();
}
答案 0 :(得分：0)
这将是您解决方案的最佳方法，请尝试使用Universal Image Loader。
功能
多线程图像加载（异步或同步）
ImageLoader配置的广泛定制（线程执行器，下载器，解码器，内存和磁盘缓存，显示图像选项等）
每个显示图像调用的许多自定义选项（存根图像，缓存切换，解码选项，位图处理和显示等）
内存和/或磁盘上的图像缓存（设备的文件系统或SD卡） 听力加载过程（包括下载进度）
在此处查找链接： https://github.com/nostra13/Android-Universal-Image-Loader