Java 使用位图从Instagram API获取图像
我已经建立了一个应用程序。我使用位图从Instagram API获取图像，并将其存储在GridView中 但我有一个问题，当我使用位图和内存缓存时 我的代码是：Java 使用位图从Instagram API获取图像,java,android,api,instagram,Java,Android,Api,Instagram,我已经建立了一个应用程序。我使用位图从Instagram API获取图像，并将其存储在GridView中 但我有一个问题，当我使用位图和内存缓存时 我的代码是： public void DisplayImage(String urrl, ImageView imageView) { String url = urrl.replaceAll(" ", "%20"); imageViews.put(imageView, url); Bitmap bitmap = memo
public void DisplayImage(String urrl, ImageView imageView) {
String url = urrl.replaceAll(" ", "%20");
imageViews.put(imageView, url);
Bitmap bitmap = memoryCache.get(url);
if (bitmap != null)
imageView.setImageBitmap(bitmap);
else {
queuePhoto(url, imageView);
imageView.setImageResource(stub_id);
}
}
bitmapmemoryCache.get（url） public class MemoryCache {
private static final String TAG = "MemoryCache";
private Map<String, Bitmap> cache= Collections.synchronizedMap(
new LinkedHashMap<String, Bitmap>(10,1.5f,true));//Last argument true for LRU ordering
private long size=0;//current allocated size
private long limit=1000000;//max memory in bytes
public MemoryCache(){
//use 25% of available heap size
setLimit(Runtime.getRuntime().maxMemory()/4);
}
public void setLimit(long new_limit){
limit=new_limit;
Log.i(TAG, "MemoryCache will use up to "+limit/1024./1024.+"MB");
}
public Bitmap get(String id){
try{
if(!cache.containsKey(id)) {
return null; }else {
//NullPointerException sometimes happen here http://code.google.com/p/osmdroid/issues/detail?id=78
return cache.get(id); }
}catch(NullPointerException ex){
ex.printStackTrace();
return null;
}
}
public void put(String id, Bitmap bitmap){
try{
if(cache.containsKey(id))
size-=getSizeInBytes(cache.get(id));
cache.put(id, bitmap);
size+=getSizeInBytes(bitmap);
checkSize();
}catch(Throwable th){
th.printStackTrace();
}
}
private void checkSize() {
Log.i(TAG, "cache size="+size+" length="+cache.size());
if(size>limit){
Iterator<Map.Entry<String, Bitmap>> iter=cache.entrySet().iterator();//least recently accessed item will be the first one iterated
while(iter.hasNext()){
Map.Entry<String, Bitmap> entry=iter.next();
size-=getSizeInBytes(entry.getValue());
iter.remove();
if(size<=limit)
break;
}
Log.i(TAG, "Clean cache. New size "+cache.size());
}
}
public void clear() {
try{
//NullPointerException sometimes happen here http://code.google.com/p/osmdroid/issues/detail?id=78
cache.clear();
size=0;
}catch(NullPointerException ex){
ex.printStackTrace();
}
}
long getSizeInBytes(Bitmap bitmap) {
if(bitmap==null)
return 0;
return bitmap.getRowBytes() * bitmap.getHeight();
}
}
对于从web url加载图像，最佳实践方法是使用Glide图像加载库 这是一个开源的图像加载库，谷歌推荐并支持它 api如下所示-
Glide
.with(context)
.load(url)
.centerCrop()
.placeholder(R.drawable.loading_spinner)
.crossFade()
.into(myImageView);
它会自动处理图像缓存（在内存和磁盘中）。这看起来是一个良好的开端，但并不完整。memoryCache.get（）有时会返回null。然后，您应该从网络请求URL，并将返回的位图添加到缓存中。该代码不存在，还是失败了？你查过了吗？我会编辑我的代码并把所有的文件都放进去，完成后你就可以看到了。谢谢您根本没有理由编写缓存类。只要用一个LRUCACHE我会试试的。。只需一分钟@GabeChan就可以用答案格式给出一个示例？例如，这是如何实现的->
myImageView=（ImageView）充气器。充气（R.layout.my\u image\u视图，容器，false）这给了我一个错误，因为您正在绑定在ImageView中强制转换布局，对吗？很有效！看完你发的东西后，终于工作了！：）非常感谢你！
public class ImageLoader {
MemoryCache memoryCache = new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews = Collections
.synchronizedMap(new WeakHashMap<ImageView, String>());
ExecutorService executorService;
Handler handler = new Handler();// handler to display images in UI thread
public ImageLoader(Context context) {
fileCache = new FileCache(context);
executorService = Executors.newFixedThreadPool(5);
}
final int stub_id = R.drawable.crayon;
public void DisplayImage(String urrl, ImageView imageView) {
String url = urrl.replaceAll(" ", "%20");
imageViews.put(imageView, url);
Bitmap bitmap = memoryCache.get(url);
if (bitmap != null)
imageView.setImageBitmap(bitmap);
else {
queuePhoto(url, imageView);
imageView.setImageResource(stub_id);
}
}
private void queuePhoto(String url, ImageView imageView) {
PhotoToLoad p = new PhotoToLoad(url, imageView);
executorService.submit(new PhotosLoader(p));
}
private Bitmap getBitmap(String url) {
File f = fileCache.getFile(url);
// from SD cache
Bitmap b = decodeFile(f);
if (b != null)
return b;
// from web
try {
Bitmap bitmap = null;
URL imageUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection) imageUrl
.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
conn.setInstanceFollowRedirects(true);
InputStream is = conn.getInputStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
conn.disconnect();
bitmap = decodeFile(f);
return bitmap;
} catch (Throwable ex) {
ex.printStackTrace();
if (ex instanceof OutOfMemoryError)
memoryCache.clear();
return null;
}
}
// decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
try {
// decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
FileInputStream stream1 = new FileInputStream(f);
BitmapFactory.decodeStream(stream1, null, o);
stream1.close();
// Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE = 70;
int width_tmp = o.outWidth, height_tmp = o.outHeight;
int scale = 1;
while (true) {
if (width_tmp / 2 < REQUIRED_SIZE
|| height_tmp / 2 < REQUIRED_SIZE)
break;
width_tmp /= 2;
height_tmp /= 2;
scale *= 2;
}
// decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
FileInputStream stream2 = new FileInputStream(f);
Bitmap bitmap = BitmapFactory.decodeStream(stream2, null, o2);
stream2.close();
return bitmap;
} catch (FileNotFoundException e) {
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
// Task for the queue
private class PhotoToLoad {
public String url;
public ImageView imageView;
public PhotoToLoad(String u, ImageView i) {
url = u;
imageView = i;
}
}
class PhotosLoader implements Runnable {
PhotoToLoad photoToLoad;
PhotosLoader(PhotoToLoad photoToLoad) {
this.photoToLoad = photoToLoad;
}
@Override
public void run() {
try {
if (imageViewReused(photoToLoad))
return;
Bitmap bmp = getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url, bmp);
if (imageViewReused(photoToLoad))
return;
BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad);
handler.post(bd);
} catch (Throwable th) {
th.printStackTrace();
}
}
}
boolean imageViewReused(PhotoToLoad photoToLoad) {
String tag = imageViews.get(photoToLoad.imageView);
if (tag == null || !tag.equals(photoToLoad.url))
return true;
return false;
}
// Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable {
Bitmap bitmap;
PhotoToLoad photoToLoad;
public BitmapDisplayer(Bitmap b, PhotoToLoad p) {
bitmap = b;
photoToLoad = p;
}
public void run() {
if (imageViewReused(photoToLoad))
return;
if (bitmap != null)
photoToLoad.imageView.setImageBitmap(bitmap);
else
photoToLoad.imageView.setImageResource(stub_id);
}
}
public void clearCache() {
memoryCache.clear();
fileCache.clear();
}
}
View view = inflater.inflate(R.layout.medialist_inflate, null);
imgView = (ImageView) view.findViewById(R.id.ivImage);
Glide.with(context).load(imageThumbList.get(position)).into(imgView);
return view;
Glide
.with(context)
.load(url)
.centerCrop()
.placeholder(R.drawable.loading_spinner)
.crossFade()
.into(myImageView);