Android - 載入圖像Url和顯示在ImageView

Question

我有此代碼可以加載圖像。服務器是安全的。 我得到了迴應：200這意味着好的。然後還要加載正確的網址。 問題是當我運行我的應用程序，圖像不會被加載。

try { 
     Bitmap bitmap=null; 
     URL imageUrl = new URL(url); 
     String userPass = username+":"+password; 
     String encode = Base64.encodeToString(userPass.getBytes(), Base64.DEFAULT); 
     HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection(); 
     conn.setRequestProperty("Authorization", "Basic " + encode); 
     conn.setConnectTimeout(10000); 
     conn.setReadTimeout(10000); 
     conn.setInstanceFollowRedirects(true); 
     int res = conn.getResponseCode(); 

     System.out.println("Response: " + res); 
     System.out.println("Image Loader URL: " + url); 

     InputStream is=conn.getInputStream(); 
     OutputStream os = new FileOutputStream(f); 
     Utils.CopyStream(is, os); 
     os.close(); 
     bitmap = decodeFile(f); 
     return bitmap; 


    } catch (Throwable ex){ 
     ex.printStackTrace(); 
     if(ex instanceof OutOfMemoryError) 
      memoryCache.clear(); 
     return null; 
    } 

private Bitmap decodeFile(File f){ 
    try { 
     //decode image size 
     BitmapFactory.Options o = new BitmapFactory.Options(); 
     o.inJustDecodeBounds = true; 
     BitmapFactory.decodeStream(new FileInputStream(f),null,o); 

     //Find the correct scale value. It should be the power of 2. 
     final int REQUIRED_SIZE=360; 
     int width_tmp=o.outWidth, height_tmp=o.outHeight; 
     Log.d("IMAGE SIZE? ", +width_tmp+ " x " + height_tmp); 
     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; 
     return BitmapFactory.decodeStream(new FileInputStream(f), null, o2); 
    } catch (FileNotFoundException e) {} 
    return null; 
} 
/// . . . . . and so on...\ 

在我logcat..one時間應該SKImageDecoder ::廠返回null

不過，也許我現在something..this我在我的logcat看..

04-17 16:18:57.936: D/libEGL(5216): loaded /system/lib/egl/libGLES_android.so 
04-17 16:18:57.940: D/libEGL(5216): loaded /vendor/lib/egl/libEGL_POWERVR_SGX540_120.so 
04-17 16:18:57.952: D/libEGL(5216): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX540_120.so 
04-17 16:18:57.955: D/libEGL(5216): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX540_120.so 
04-17 16:18:58.087: D/OpenGLRenderer(5216): Enabling debug mode 0 

我想我的圖像被解碼，因爲我登錄IMAGE SIZE?：然後它記錄了我想要加載的圖像的右側圖像大小。

ImageLoader或渲染部分的問題？

請任何見解。謝謝。

Answer 1

嘗試用這個類，它的緩存下載的圖片背景和存儲：

import java.io.IOException; 
import java.io.InputStream; 
import java.net.MalformedURLException; 
import java.net.URL; 
import java.net.URLConnection; 
import java.util.Collections; 
import java.util.HashMap; 
import java.util.LinkedList; 
import java.util.Map; 
import java.util.WeakHashMap; 
import java.util.concurrent.ExecutorService; 
import java.util.concurrent.Executors; 

import android.graphics.drawable.Drawable; 
import android.os.Handler; 
import android.os.Message; 
import android.widget.ImageView; 




/** 
* This Class is for download images and assign the drawable to an ImageView. 
* 
*/ 
public class DrawableBackgroundDownloader {  

private final Map<String, Drawable> mCache = new HashMap<String, Drawable>(); 
private final LinkedList <Drawable> mChacheController = new LinkedList <Drawable>(); 
private ExecutorService mThreadPool; 
private final Map<ImageView, String> mImageViews = Collections.synchronizedMap(new WeakHashMap<ImageView, String>()); 
public static int MAX_CACHE_SIZE = 80; 
public int THREAD_POOL_SIZE = 3; 



/** 
* Constructor 
*/ 
public DrawableBackgroundDownloader() { 
    mThreadPool = Executors.newFixedThreadPool(THREAD_POOL_SIZE); 
} 


/** 
* Clears all instance data and stops running threads 
*/ 
public void Reset() { 
    ExecutorService oldThreadPool = mThreadPool; 
    mThreadPool = Executors.newFixedThreadPool(THREAD_POOL_SIZE); 
    oldThreadPool.shutdownNow(); 

    mChacheController.clear(); 
    mCache.clear(); 
    mImageViews.clear(); 
} 

/** 
* Load the drawable associated to a url and assign it to an image, you can set a placeholder to replace this drawable. 
* @param url Is the url of the image. 
* @param imageView The image to assign the drawable. 
* @param placeholder A drawable that is show during the image is downloading. 
*/ 
public void loadDrawable(final String url, final ImageView imageView,Drawable placeholder) { 
    if(!mImageViews.containsKey(url)) 
     mImageViews.put(imageView, url); 
    Drawable drawable = getDrawableFromCache(url); 

    // check in UI thread, so no concurrency issues 
    if (drawable != null) { 
     //Log.d(null, "Item loaded from mCache: " + url); 
     imageView.setImageDrawable(drawable); 
    } else { 
     imageView.setImageDrawable(placeholder); 
     queueJob(url, imageView, placeholder); 
    } 
} 


/** 
* Return a drawable from the cache. 
* @param url url of the image. 
* @return a Drawable in case that the image exist in the cache, else returns null. 
*/ 
public Drawable getDrawableFromCache(String url) { 
    if (mCache.containsKey(url)) { 
     return mCache.get(url); 
    } 

    return null; 
} 


/** 
* Save the image to cache memory. 
* @param url The image url 
* @param drawable The drawable to save. 
*/ 
private synchronized void putDrawableInCache(String url,Drawable drawable) { 
    int chacheControllerSize = mChacheController.size(); 
    if (chacheControllerSize > MAX_CACHE_SIZE) 
     mChacheController.subList(0, MAX_CACHE_SIZE/2).clear(); 

    mChacheController.addLast(drawable); 
    mCache.put(url, drawable); 

} 

/** 
* Queue the job to download the image. 
* @param url Image url. 
* @param imageView The ImageView where is assigned the drawable. 
* @param placeholder The drawable that is show during the image is downloading. 
*/ 
private void queueJob(final String url, final ImageView imageView,final Drawable placeholder) { 
    /* Create handler in UI thread. */ 
    final Handler handler = new Handler() { 
     @Override 
     public void handleMessage(Message msg) { 
      String tag = mImageViews.get(imageView); 
      if (tag != null && tag.equals(url)) { 
       if (imageView.isShown()) 
        if (msg.obj != null) { 
         imageView.setImageDrawable((Drawable) msg.obj); 
        } else { 
         imageView.setImageDrawable(placeholder); 
         //Log.d(null, "fail " + url); 
        } 
      } 
     } 
    }; 

    mThreadPool.submit(new Runnable() { 
     public void run() { 
      final Drawable bmp = downloadDrawable(url); 
      // if the view is not visible anymore, the image will be ready for next time in cache 
      if (imageView.isShown()) 
      { 
       Message message = Message.obtain(); 
       message.obj = bmp; 
       //Log.d(null, "Item downloaded: " + url); 

       handler.sendMessage(message); 
      } 
     } 
    }); 
} 


/** 
* Method that download the image 
* @param url The url image. 
* @return Returns the drawable associated to this image. 
*/ 
private Drawable downloadDrawable(String url) { 
    try { 
     InputStream is = getInputStream(url); 

     Drawable drawable = Drawable.createFromStream(is, url); 
     putDrawableInCache(url,drawable); 
     return drawable; 

    } catch (MalformedURLException e) { 
     e.printStackTrace(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 

    return null; 
} 

/** 
* This method manage the connection to download the image. 
* @param urlString url of the image. 
* @return Returns an InputStream associated with the url image. 
* @throws MalformedURLException 
* @throws IOException 
*/ 
private InputStream getInputStream(String urlString) throws MalformedURLException, IOException { 
    URL url = new URL(urlString); 
    URLConnection connection; 
    connection = url.openConnection(); 
    connection.setUseCaches(true); 
    connection.connect(); 
    InputStream response = connection.getInputStream(); 

    return response; 
} 
} 

易於使用只是聲明：

DrawableBackgroundDownloader drawableDownloader = new DrawableBackgroundDownloader(); 

，並在那裏你想使用：

drawableDownloader.loadDrawable(String urlImage, ImageView iView,Drawable drawable); 

其中drawable是圖像下載期間顯示的Drawable。