Use LruCache and DiskLruCache to download images,

Use LruCache and DiskLruCache to download images,

LruCache is a good image caching tool:

The main method is to cache the bitmap of the image in LruCache <String, Bitmap> when sliding the image. After exiting the program, the image is cached in the file and the DiskLruCache mDiskLruCache is used.

Therefore, we must set an image cache address:

public void setImageCache(){    String strPath = null;    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {    File sdFile = Environment.getExternalStorageDirectory();    strPath = sdFile.getAbsolutePath() + "/pic/";    File cacheFile = new File(strPath);        if(!cacheFile.exists()){        cacheFile.mkdir();        }    }    else{    String strCacheDir = this.getCacheDir().getAbsolutePath();    strPath = strCacheDir + "/pic/";    }    setCachePath(strPath);    }private void setCachePath(String strPicCachePath){if(TextUtils.isEmpty(strPicCachePath)){return;}m_strPicCachePath = strPicCachePath;File cacheFile = new File(strPicCachePath);        if(!cacheFile.exists()){        cacheFile.mkdir();        }}public String getCacheBmpPath(String strUrl){if(TextUtils.isEmpty(m_strPicCachePath) || TextUtils.isEmpty(strUrl)){return "";}return m_strPicCachePath + StringUtil.MD5Encode(strUrl) + mFileExName;//".bmp";}

Then write the List adapter:

Private class ListAdapter extends BaseAdapter implements OnScrollListener {protected List <ShopData> items = new ArrayList <ShopData> (); protected static final int priority = 1; private LruCache <String, Bitmap> mMemoryCache; protected HashSet <ImageView> mItemsMissingImages = new HashSet <ImageView> (); protected ImageLoaderHandler mHandler; protected ImageLoader mImageFetcher; public static final int TIMEOUT = 30000; // TIMEOUT time 30 seconds private DiskLruCache mDiskLruCache; public ListAdapter () {super (); mHandler = new ImageLoaderHandler (); int maxMemory = (int) Runtime. getRuntime (). maxMemory (); int mCacheSize = maxMemory/8; // allocate 1/8 4 MmMemoryCache = new LruCache <String, Bitmap> (mCacheSize) to LruCache {// This method must be rewritten, to measure the Bitmap size @ Overrideprotected int sizeOf (String key, Bitmap value) {return value. getRowBytes () * v Alue. getHeight () ;}; try {mDiskLruCache = DiskLruCache. open (new File (m_strPicCachePath), getAppVersion (MainActivityTest. this), 1, 10*1024*1024);} catch (IOException e) {e. printStackTrace () ;}}/*** synchronize cache records to the journal File. */Public void fluchCache () {if (mDiskLruCache! = Null) {try {mDiskLruCache. flush ();} catch (IOException e) {e. printStackTrace () ;}}@ Overridepublic int getCount () {return items. size () ;}@ Overridepublic Object getItem (int position) {return items. get (position) ;}@ Overridepublic long getItemId (int position) {return position ;}@ Overridepublic View getView (int position, View convertView, ViewGroup parent) {ShopDataTag tag = new ShopDataTag (); if (convert View = null) {convertView = mInflater. inflate (R. layout. listitem, null); tag. name = (TextView) convertView. findViewById (R. id. name); tag. shopInfo = (TextView) convertView. findViewById (R.id.info); tag. icon = (ImageView) convertView. findViewById (R. id. image_icon); convertView. setTag (tag);} else {tag = (ShopDataTag) convertView. getTag ();} TextView name = tag. name; TextView info = tag. shopInfo; ImageView image View = tag. icon; ShopData data = items. get (position); name. setText (data. name); info. setText (data.info); imageView. setTag (data. url); setContactPhoto (data. url, imageView); return convertView;} protected void setContactPhoto (String url, ImageView viewToUse) {if (TextUtils. isEmpty (url) {viewToUse. setImageResource (R. drawable. avatar);} else {// check whether bitmapBitmap bitmap = mMemoryCache is available in mMemoryCache. get (url); if (B Itmap! = Null) {viewToUse. setImageBitmap (bitmap);} else {Snapshot snapShot = null; FileDescriptor fileDescriptor = null; FileInputStream fileInputStream = null; try {// because mDiskLruCache uses the key as the file name, therefore, convert the url to keyfinal String key = hashKeyForDisk (url) through md5; snapShot = mDiskLruCache. get (key); // if snapShot is empty, the corresponding file if (snapShot = null) is not found {// download fetchImage (viewToUse) here );} else {fileInputStream = (FileInputStream) snapShot. GetInputStream (0); fileDescriptor = fileInputStream. getFD (); if (fileDescriptor! = Null) {bitmap = BitmapFactory. decodeFileDescriptor (fileDescriptor);} // if the file fails to be parsed as bitmap, download it again if (! TextUtils. isEmpty (url) & bitmap! = Null) {mMemoryCache. put (url, bitmap); viewToUse. setImageBitmap (bitmap);} else {fetchImage (viewToUse) ;}} catch (IOException ex) {ex. printStackTrace ();} finally {if (fileDescriptor = null & fileInputStream! = Null) {try {fileInputStream. close () ;}catch (IOException e) {}}}} private void fetchImage (ImageView viewToUse) {viewToUse. setImageResource (R. drawable. avatar); mItemsMissingImages. add (viewToUse); if (mScrollState! = OnScrollListener. SCROLL_STATE_FLING) {sendFetchImageMessage (viewToUse) ;}} public String <strong> hashKeyForDisk </strong> (String key) {convert the key to the md5 file return StringUtil. MD5Encode (key);} // image downloaderprivate class ImageLoaderHandler extends Handler {@ Overridepublic void handleMessage (Message message) {if (isFinishing () {return;} switch (message. what) {case FETCH_IMAGE_MSG: {final ImageView imageVie W = (ImageView) message. obj; if (imageView = null) {break;} final String url = (String) imageView. getTag (); if (TextUtils. isEmpty (url) {break;} Bitmap map = getBitmapFromMemCache (url); if (map = null) {break;} synchronized (imageView) {final String myUrl = (String) imageView. getTag (); if (TextUtils. equals (url, myUrl) {imageView. setImageBitmap (map); mItemsMissingImages. remove (imageView);} else {}} break ;}} Public void clearImageFecthing () {removeMessages (FETCH_IMAGE_MSG) ;}} private class ImageLoader implements Runnable {String url; private ImageView mImageView; public ImageLoader (String url, ImageView imageView) {this. url = url; this. mImageView = imageView;} public void run () {if (isFinishing () {return;} if (Thread. interrupted () {return;} FileDescriptor fileDescriptor = null; FileInputStream fileInput Stream = null; Snapshot snapShot = null; try {final String key = hashKeyForDisk (url); snapShot = mDiskLruCache. get (key); if (snapShot = null) {// if the corresponding cache is not found, request data from the network and write it to the cache DiskLruCache. editor editor = mDiskLruCache. edit (key); if (editor! = Null) {OutputStream outputStream = editor. newOutputStream (0); boolean flag = downloadImage (url, outputStream); if (flag) {editor. commit ();} else {editor. abort () ;}// after the cache is written, find the cache snapShot = mDiskLruCache corresponding to the key again. get (key) ;}// Delete the corresponding object if (snapShot! = Null) {fileInputStream = (FileInputStream) snapShot. getInputStream (0); fileDescriptor = fileInputStream. getFD () ;}// resolve the cached data to the Bitmap object Bitmap bitmap = null; if (fileDescriptor! = Null) {bitmap = BitmapFactory. decodeFileDescriptor (fileDescriptor);} if (bitmap! = Null) {// Add a Bitmap object to the memory cache. put (url, bitmap) ;}} catch (IOException e) {e. printStackTrace ();} finally {if (fileDescriptor = null & fileInputStream! = Null) {try {fileInputStream. close () ;}catch (IOException e) {}} if (Thread. interrupted () {return;} Message msg = new Message (); msg. what = FETCH_IMAGE_MSG; msg. obj = mImageView; mHandler. sendMessage (msg) ;}} public Bitmap getBitmapFromMemCache (String key) {return mMemoryCache. get (key);} public boolean downloadImage (String strUrl, OutputStream fos) {URL getUrl = null; Bitmap bitmap = null; BufferedOutpu TStream out = null; BufferedInputStream in = null; try {getUrl = new URL (strUrl);} catch (MalformedURLException ex) {Log. e ("HttpUtil", "get MalformedURL", ex); return false;} InputStream input = null; HttpURLConnection conn = null; try {conn = (HttpURLConnection) getUrl. openConnection (); conn. setConnectTimeout (TIMEOUT); conn. setReadTimeout (TIMEOUT); conn. setDoInput (true); conn. connect (); input = conn. getInput Stream (); in = new BufferedInputStream (input, 8*1024); out = new BufferedOutputStream (fos, 8*1024); int B; while (B = in. read ())! =-1) {out. write (B);} return true;} catch (Exception ex) {Log. e ("HttpUtil", "downloadImage", ex);} catch (OutOfMemoryError ex) {ex. printStackTrace ();} finally {try {if (out! = Null) {out. close (); out = null;} if (in! = Null) {in. close (); in = null;} if (conn! = Null) {conn. disconnect (); conn = null ;}} catch (Exception ex) {Log. e ("HttpUtil", "downloadImage finally", ex) ;}return false;} private boolean getResponse (InputStream input, OutputStream OS, byte [] data) throws IOException {if (input = null | OS = null | data = null) {return false;} int I = 0; while (I = input. read (data ))! =-1) {OS. write (data, 0, I); OS. flush ();} OS. flush (); return true;} private void processMissingImageItems (AbsListView view) {for (ImageView iv: Images) {sendFetchImageMessage (iv) ;}} protected void sendFetchImageMessage (ImageView view) {final String url = (String) view. getTag (); if (TextUtils. isEmpty (url) {return;} mImageFetcher = new ImageLoader (url, view); synchronized (MainActivityTest. this) {If (sImageFetchThreadPool = null) {sImageFetchThreadPool = effeccute (mImageFetcher) ;}} public void clearImageFetching () {synchronized (MainActivityTest. this) {if (response! = Null) {sImageFetchThreadPool. shutdownNow (); sImageFetchThreadPool = null ;}} mHandler. clearImageFecthing ();} public void clearMessages () {if (mHandler! = Null) {try {mHandler. removeCallbacksAndMessages (null);} catch (java. lang. throwable th) {} mHandler = null ;}@ Overridepublic void onScrollStateChanged (AbsListView view, int scrollState) {mScrollState = scrollState; if (scrollState = OnScrollListener. topology) {clearImageFetching () ;}else {processMissingImageItems (view) ;}@overridepublic void onScroll (AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {}} private class ShopDataTag {TextView name; TextView shopInfo; ImageView icon ;}

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Code: http://download.csdn.net/detail/baidu_nod/7777137