Android的延迟加载不显示图像上的电话或显示与慢 [英] android lazy loading not showing images on phone or showing and is slow
问题描述
我使用JSON解析在线XML文档,还设有2个方法懒图像加载。下面是我的源$ C $ C,说明我的问题:
说明:
方法1:
使用的AsyncTask
与行 imageLoader.DisplayImage((字符串)jsonImageText.get(IMAGELINK),活动,ImageView的);
适配器内。
方法2:
不使用的AsyncTask
,并使用try-catch块的其余部分,都不行 imageLoader.DisplayImage((字符串)jsonImageText.get( IMAGELINK),活动,ImageView的);
的问题:
方法1:
图像显示在仿真器和负载量为pretty的速度快,但他们无法显示在手机或平板电脑。
方法2:
的图像被显示在所有的仿真器和实际设备,但装载和滚动速度非常慢。
有没有什么办法来解决或者这2种方法,甚至两者的?
这是列表适配器返回ListView的行观点:
公共类RssListAdapter扩展ArrayAdapter<的JSONObject> {
公共ImageLoader的ImageLoader的;
公共RssListAdapter(活动活动,列表和LT;的JSONObject> imageAndTexts){
超级(活性,0,imageAndTexts);
ImageLoader的=新ImageLoader的(activity.getApplicationContext());
}
@覆盖
公共查看getView(INT位置,查看convertView,ViewGroup中父){
活动活性=(活动)的getContext();
LayoutInflater充气= activity.getLayoutInflater();
//从充气XML的意见
查看rowView = inflater.inflate(R.layout.image_text_layout,NULL);
JSONObject的jsonImageText =的getItem(位置);
TextView中的TextView =(TextView中)rowView.findViewById(R.id.job_text);
ImageView的ImageView的=(ImageView的)rowView.findViewById(R.id.feed_image);
尝试 {
如果(jsonImageText.get(IMAGELINK)!= NULL){
的System.out.println(XXXX链接找到了!);
字符串URL =(字符串)jsonImageText.get(IMAGELINK);
URL feedImage =新的网址(URL);
HttpURLConnection的康恩=(HttpURLConnection类)feedImage.openConnection();
InputStream的是= conn.getInputStream();
位图IMG = BitmapFactory.de codeStream(是);
imageView.setImageBitmap(IMG);
//imageLoader.DisplayImage((String)jsonImageText.get("imageLink),活动,ImageView的);
}
跨区文字=(跨区)jsonImageText.get(文字);
textView.setText(文本);
}
赶上(MalformedURLException的E){
textView.setText(JSON异常);
}
赶上(IOException异常E){
textView.setText(JSON异常);
}
赶上(JSONException E){
textView.setText(JSON异常);
}
返回rowView;
}
}
这是ImageLoader的类:
公共类ImageLoader的{
的MemoryCache的MemoryCache =新的MemoryCache();
FileCache fileCache;
私人地图< ImageView的,字符串> imageViews = Collections.synchronizedMap(新的WeakHashMap< ImageView的,字符串>());
公共ImageLoader的(上下文的背景下){
//使后台线程低优先级。这样也不会影响用户界面性能
photoLoaderThread.setPriority(Thread.NORM_PRIORITY-1);
fileCache =新FileCache(上下文);
}
最终诠释stub_id = R.drawable.icon;
公共无效DisplayImage(字符串URL,活动活动,ImageView的ImageView的)
{
imageViews.put(ImageView的,URL);
点阵位图= memoryCache.get(URL);
如果(位图!= NULL)
imageView.setImageBitmap(位);
其他
{
queuePhoto(URL,活动,ImageView的);
imageView.setImageResource(stub_id);
}
}
私人无效queuePhoto(字符串URL,活动活动,ImageView的ImageView的)
{
//这个ImageView的可之前用于其它图像。所以有可能在队列一些旧的任务。我们需要将它们丢弃。
photosQueue.Clean(ImageView的);
PhotoToLoad P =新PhotoToLoad(URL,ImageView的);
同步(photosQueue.photosToLoad){
photosQueue.photosToLoad.push(对);
photosQueue.photosToLoad.notifyAll();
}
//启动线程,如果它尚未开始
如果(photoLoaderThread.getState()== Thread.State.NEW)
photoLoaderThread.start();
}
私人位图getBitmap(字符串URL)
{
文件F = fileCache.getFile(URL);
//从SD高速缓存
位图B =去codeFILE(F);
如果(B!= NULL)
返回b;
//从网页
尝试 {
点阵位图= NULL;
URL IMAGEURL =新的网址(URL);
HttpURLConnection的康恩=(HttpURLConnection类)imageUrl.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
InputStream的是= conn.getInputStream();
的OutputStream OS =新的FileOutputStream(F);
Utils.CopyStream(是,OS);
os.close();
位=去codeFILE(F);
返回的位图;
}赶上(例外前){
ex.printStackTrace();
返回null;
}
}
//德$ C $连拍影像和扩展它来减少内存消耗
私人位图德codeFILE(文件f){
尝试 {
//德code图像尺寸
BitmapFactory.Options O =新BitmapFactory.Options();
o.inJustDe codeBounds = TRUE;
BitmapFactory.de codeStream(新的FileInputStream(f)项,空,O);
//找到正确的比例值。它应该是2的幂。
最终诠释REQUIRED_SIZE = 70;
INT width_tmp = o.outWidth,height_tmp = o.outHeight;
int标= 1;
而(真){
如果(width_tmp / 2'; REQUIRED_SIZE || height_tmp / 2'; REQUIRED_SIZE)
打破;
width_tmp / = 2;
height_tmp / = 2;
规模* = 2;
}
//德code与inSampleSize
BitmapFactory.Options O2 =新BitmapFactory.Options();
o2.inSampleSize =规模;
返回BitmapFactory.de codeStream(新的FileInputStream(f)项,空,O2);
}赶上(FileNotFoundException异常E){}
返回null;
}
//任务队列
私有类PhotoToLoad
{
公共字符串URL;
公众的ImageView ImageView的;
公共PhotoToLoad(字符串U,ImageView的我){
URL = U;
ImageView的=我;
}
}
PhotosQueue photosQueue =新PhotosQueue();
公共无效stopThread()
{
photoLoaderThread.interrupt();
}
//照片商店列表下载
类PhotosQueue
{
私人堆叠式和LT; PhotoToLoad> photosToLoad =新的堆栈< PhotoToLoad>();
//删除这个ImageView的所有实例
公共无效清洁(ImageView的图像)
{
对于(INT J = 0; J< photosToLoad.size()){
如果(photosToLoad.get(J).imageView ==图片)
photosToLoad.remove(J);
其他
+ D];
}
}
}
类PhotosLoader继承Thread {
公共无效的run(){
尝试 {
而(真)
{
//线程等待直到有在队列加载任何图像
如果(photosQueue.photosToLoad.size()== 0)
同步(photosQueue.photosToLoad){
photosQueue.photosToLoad.wait();
}
如果(photosQueue.photosToLoad.size()!= 0)
{
PhotoToLoad photoToLoad;
同步(photosQueue.photosToLoad){
photoToLoad = photosQueue.photosToLoad.pop();
}
BMP位= getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url,BMP);
字符串变量= imageViews.get(photoToLoad.imageView);
如果(标记= NULL和放大器;!&安培; tag.equals(photoToLoad.url)){
BitmapDisplayer BD =新BitmapDisplayer(BMP,photoToLoad.imageView);
活动一=(活动)photoToLoad.imageView.getContext();
a.runOnUiThread(BD);
}
}
如果(Thread.interrupted())
打破;
}
}赶上(InterruptedException异常E){
//允许线程退出
}
}
}
PhotosLoader photoLoaderThread =新PhotosLoader();
//用于在UI线程中显示位图
类BitmapDisplayer实现Runnable
{
点阵位图;
ImageView的ImageView的;
公共BitmapDisplayer(位图B,ImageView的我){位= B,ImageView的= I;}
公共无效的run()
{
如果(位图!= NULL)
imageView.setImageBitmap(位);
其他
imageView.setImageResource(stub_id);
}
}
公共无效clearCache(){
memoryCache.clear();
fileCache.clear();
}
}
您可以尝试延迟加载图像和ListView aquery的Android库......下面code可以帮助你......的从这里下载库? >
AQuery AQ =新AQuery(mContext);
aq.id(R.id.image1)图像配(http://data.whicdn.com/images/63995806/original.jpg);
I am using JSON to parse an online xml document and also 2 methods for lazy image loading. Below is my source code, explanation and my problem:
Explanation:
Method 1:
Use AsyncTask
and line imageLoader.DisplayImage((String)jsonImageText.get("imageLink"), activity, imageView);
inside the adapter.
Method 2:
Not use AsyncTask
and use the rest of the try-catch block and NOT the line imageLoader.DisplayImage((String)jsonImageText.get("imageLink"), activity, imageView);
The problems:
Method 1:
The images are displayed on the emulator and the loading is pretty fast, but they fail to display on a phone or a tablet.
Method 2:
The images are displayed on all the emulators and real devices, but the loading and scrolling are very slow.
Is there any way to fix either of these 2 methods or even both?
This is the list adapter which returns the ListView's row view:
public class RssListAdapter extends ArrayAdapter<JSONObject> {
public ImageLoader imageLoader;
public RssListAdapter(Activity activity, List<JSONObject> imageAndTexts) {
super(activity, 0, imageAndTexts);
imageLoader=new ImageLoader(activity.getApplicationContext());
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Activity activity = (Activity) getContext();
LayoutInflater inflater = activity.getLayoutInflater();
// Inflate the views from XML
View rowView = inflater.inflate(R.layout.image_text_layout, null);
JSONObject jsonImageText = getItem(position);
TextView textView = (TextView) rowView.findViewById(R.id.job_text);
ImageView imageView = (ImageView) rowView.findViewById(R.id.feed_image);
try {
if (jsonImageText.get("imageLink") != null){
System.out.println("XXXX Link found!");
String url = (String) jsonImageText.get("imageLink");
URL feedImage= new URL(url);
HttpURLConnection conn= (HttpURLConnection)feedImage.openConnection();
InputStream is = conn.getInputStream();
Bitmap img = BitmapFactory.decodeStream(is);
imageView.setImageBitmap(img);
//imageLoader.DisplayImage((String)jsonImageText.get("imageLink"), activity, imageView);
}
Spanned text = (Spanned)jsonImageText.get("text");
textView.setText(text);
}
catch (MalformedURLException e) {
textView.setText("JSON Exception");
}
catch (IOException e) {
textView.setText("JSON Exception");
}
catch (JSONException e) {
textView.setText("JSON Exception");
}
return rowView;
}
}
This is the ImageLoader class:
public class ImageLoader {
MemoryCache memoryCache=new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews=Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
public ImageLoader(Context context){
//Make the background thread low priority. This way it will not affect the UI performance
photoLoaderThread.setPriority(Thread.NORM_PRIORITY-1);
fileCache=new FileCache(context);
}
final int stub_id=R.drawable.icon;
public void DisplayImage(String url, Activity activity, ImageView imageView)
{
imageViews.put(imageView, url);
Bitmap bitmap=memoryCache.get(url);
if(bitmap!=null)
imageView.setImageBitmap(bitmap);
else
{
queuePhoto(url, activity, imageView);
imageView.setImageResource(stub_id);
}
}
private void queuePhoto(String url, Activity activity, ImageView imageView)
{
//This ImageView may be used for other images before. So there may be some old tasks in the queue. We need to discard them.
photosQueue.Clean(imageView);
PhotoToLoad p=new PhotoToLoad(url, imageView);
synchronized(photosQueue.photosToLoad){
photosQueue.photosToLoad.push(p);
photosQueue.photosToLoad.notifyAll();
}
//start thread if it's not started yet
if(photoLoaderThread.getState()==Thread.State.NEW)
photoLoaderThread.start();
}
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);
InputStream is=conn.getInputStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
bitmap = decodeFile(f);
return bitmap;
} catch (Exception ex){
ex.printStackTrace();
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;
BitmapFactory.decodeStream(new FileInputStream(f),null,o);
//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;
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e) {}
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;
}
}
PhotosQueue photosQueue=new PhotosQueue();
public void stopThread()
{
photoLoaderThread.interrupt();
}
//stores list of photos to download
class PhotosQueue
{
private Stack<PhotoToLoad> photosToLoad=new Stack<PhotoToLoad>();
//removes all instances of this ImageView
public void Clean(ImageView image)
{
for(int j=0 ;j<photosToLoad.size();){
if(photosToLoad.get(j).imageView==image)
photosToLoad.remove(j);
else
++j;
}
}
}
class PhotosLoader extends Thread {
public void run() {
try {
while(true)
{
//thread waits until there are any images to load in the queue
if(photosQueue.photosToLoad.size()==0)
synchronized(photosQueue.photosToLoad){
photosQueue.photosToLoad.wait();
}
if(photosQueue.photosToLoad.size()!=0)
{
PhotoToLoad photoToLoad;
synchronized(photosQueue.photosToLoad){
photoToLoad=photosQueue.photosToLoad.pop();
}
Bitmap bmp=getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url, bmp);
String tag=imageViews.get(photoToLoad.imageView);
if(tag!=null && tag.equals(photoToLoad.url)){
BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad.imageView);
Activity a=(Activity)photoToLoad.imageView.getContext();
a.runOnUiThread(bd);
}
}
if(Thread.interrupted())
break;
}
} catch (InterruptedException e) {
//allow thread to exit
}
}
}
PhotosLoader photoLoaderThread=new PhotosLoader();
//Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable
{
Bitmap bitmap;
ImageView imageView;
public BitmapDisplayer(Bitmap b, ImageView i){bitmap=b;imageView=i;}
public void run()
{
if(bitmap!=null)
imageView.setImageBitmap(bitmap);
else
imageView.setImageResource(stub_id);
}
}
public void clearCache() {
memoryCache.clear();
fileCache.clear();
}
}
you can try aquery android library for lazy loading image and listview...below code may help you..... download library from here
AQuery aq = new AQuery(mContext);
aq.id(R.id.image1).image("http://data.whicdn.com/images/63995806/original.jpg");
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