缓存图像和显示

Question

缓存图像和显示

D'y*_*'er 16 android json imageview lazylist universal-image-loader

您好我面临一个特殊的问题,我需要下载图像并将其显示在ListView对应的特定对象上TextView's.我的代码是成功显示TextView's我需要显示但我不知道如何在我的文本视图旁边显示所有这些不同的图像ListView.

经过SO中的许多线程之后.最佳答案是通过1.懒惰列表2.通用图像加载器来解决这个问题

我已经完成了两个解决方案.我下载了Lazy List代码,其中URL是存储在Array中的硬编码字符串.我想做的是动态创建自己的字符串.将它们存储在缓存中并显示所有相应的图像.

这是我的代码:

public class Tools_ListItemActivity extends ListActivity 
{
    private Context context;
    String s;

    private static final String TAG_POSTS = "posts";
    private static final String TAG_MDNAME = "mdname";
    private static final String TAG_UTCOST = "utcost";
    private static final String TAG_IIMG= "iimg";
    JSONArray posts = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);
        s=getIntent().getExtras().getString("url");
        new ProgressTask(Tools_ListItemActivity.this).execute();
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        // TODO Auto-generated method stub
        super.onListItemClick(l, v, position, id);
    }

ArrayList<HashMap<String, String>> jsonlist = new ArrayList<HashMap<String, String>>();

     ListView lv ;



      private class ProgressTask extends AsyncTask<String, Void, Boolean> {
      private ProgressDialog dialog;

       public ProgressTask(ListActivity activity) {

       Log.i("1", "Called");
       context = activity;
       dialog = new ProgressDialog(context);
      }

       /** progress dialog to show user that the backup is processing. */

       /** application context. */
      private Context context;

       protected void onPreExecute() {
       this.dialog.setMessage("Progress start");
       this.dialog.show();
      }

       @Override
      protected void onPostExecute(final Boolean success) {
       if (dialog.isShowing()) {
        dialog.dismiss();
       }
       ListAdapter adapter = new SimpleAdapter(context, jsonlist,
         R.layout.activity_toolsitem, new String[] { TAG_IIMG, TAG_MDNAME, TAG_UTCOST  }, new int[] {
           R.id.imageViewUrl, R.id.mdname, R.id.utcost });

        setListAdapter(adapter);

        // selecting single ListView item
        lv = getListView();

      }

       protected Boolean doInBackground(final String... args) {

        JSONParser jParser = new JSONParser();

        // getting JSON string from URL
        JSONObject json = jParser.getJSONFromUrl(s);


        try {
            posts = json.getJSONArray(TAG_POSTS);
        } catch (JSONException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        try
        {
        // looping through All Contacts
        for(int i = 0; i < posts.length(); i++){
            JSONObject c = posts.getJSONObject(i);

            // Storing each json item in variable
            String mdname = c.getString(TAG_MDNAME);
            String utcost= c.getString(TAG_UTCOST);
            String iimg=c.getString(TAG_IIMG);

            //Forming the Url of the image to be shown in the list view
            String imageUrl="My_App_URL"+iimg;

/*  try {

              String imageUrl="My_App_URL"+iimg;
              ImageView imageView = (ImageView)findViewById(R.id.imageViewUrl);
              Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(imageUrl).getContent());
              imageView.setImageBitmap(bitmap); 
            } catch (MalformedURLException e) {
              e.printStackTrace();
            } catch (IOException e) {
              e.printStackTrace();
            } */


            // creating new HashMap
            HashMap<String, String> map = new HashMap<String, String>();

            // adding each child node to HashMap key => value
            map.put(TAG_MDNAME, mdname);
            map.put(TAG_UTCOST, utcost);
            map.put(TAG_IIMG, iimg);



         jsonlist.add(map);
        } }catch (JSONException e) 
        {
         // TODO Auto-generated catch block
         e.printStackTrace();
        }


        return null;


       }

      }





}

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在这里,我已经调试,发现imageUrl正确形成.Json只返回jpg所以我将其附加到URL并将其存储在其中的名称imageUrl.其他两个文本视图正在被正确解析和显示.如果任何人都可以帮助我在图像视图中显示图像,那么它会很棒.谢谢.

更新: 借助Pankaj共享的链接(https://github.com/AndroidBegin/Android-JSON-Parse-Images-and-Texts-Tutorial)和共享的概念知识,我能够解决我的特定问题. Raghunandan下面.请仔细阅读这些答案,以获取详细解释以及延迟加载的实现.我很抱歉因为我离开了两天而无法以赏金回报答案.

Answer 1

Rag*_*dan 17

使用Universal Imageloader进行延迟加载.用图像的url替换硬编码的url.

根据您的要求修改以下内容

什么是LazyList？.请查看此链接了解详情.

MainActivity.java

public class MainActivity extends Activity {

  private String[] mStrings={
            "http://a3.twimg.com/profile_images/670625317/aam-logo-v3-twitter.png",
            "http://a3.twimg.com/profile_images/740897825/AndroidCast-350_normal.png",
            "http://a3.twimg.com/profile_images/121630227/Droid_normal.jpg",
            "http://a1.twimg.com/profile_images/957149154/twitterhalf_normal.jpg",
            "http://a1.twimg.com/profile_images/97470808/icon_normal.png",
            "http://a3.twimg.com/profile_images/511790713/AG.png",
            "http://a3.twimg.com/profile_images/956404323/androinica-avatar_normal.png",
            "http://a1.twimg.com/profile_images/909231146/Android_Biz_Man_normal.png",
            "http://a3.twimg.com/profile_images/72774055/AndroidHomme-LOGO_normal.jpg",
            "http://a1.twimg.com/profile_images/349012784/android_logo_small_normal.jpg",
            "http://a1.twimg.com/profile_images/841338368/ea-twitter-icon.png",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet_normal.png",
            "http://a1.twimg.com/profile_images/605536070/twitterProfilePhoto_normal.jpg",
            "http://a1.twimg.com/profile_images/850960042/elandroidelibre-logo_300x300_normal.jpg",
            "http://a1.twimg.com/profile_images/655119538/andbook.png",
            "http://a3.twimg.com/profile_images/768060227/ap4u_normal.jpg",
            "http://a1.twimg.com/profile_images/74724754/android_logo_normal.png",
            "http://a3.twimg.com/profile_images/681537837/SmallAvatarx150_normal.png",
            "http://a1.twimg.com/profile_images/63737974/2008-11-06_1637_normal.png",
            "http://a3.twimg.com/profile_images/548410609/icon_8_73.png",
            "http://a1.twimg.com/profile_images/612232882/nexusoneavatar_normal.jpg",
            "http://a1.twimg.com/profile_images/213722080/Bugdroid-phone_normal.png",
            "http://a1.twimg.com/profile_images/645523828/OT_icon_090918_android_normal.png",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet.png",
            "http://a1.twimg.com/profile_images/605536070/twitterProfilePhoto_normal.jpg",
            "http://a1.twimg.com/profile_images/850960042/elandroidelibre-logo_300x300_normal.jpg",
            "http://a1.twimg.com/profile_images/655119538/andbook_normal.png",
            "http://a3.twimg.com/profile_images/511790713/AG_normal.png",
            "http://a3.twimg.com/profile_images/956404323/androinica-avatar.png",
            "http://a1.twimg.com/profile_images/909231146/Android_Biz_Man_normal.png",
            "http://a3.twimg.com/profile_images/72774055/AndroidHomme-LOGO_normal.jpg",
            "http://a1.twimg.com/profile_images/349012784/android_logo_small_normal.jpg",
            "http://a1.twimg.com/profile_images/841338368/ea-twitter-icon_normal.png",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet.png",
            "http://a1.twimg.com/profile_images/605536070/twitterProfilePhoto_normal.jpg",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet_normal.png",
            "http://a1.twimg.com/profile_images/605536070/twitterProfilePhoto_normal.jpg",
            "http://a1.twimg.com/profile_images/850960042/elandroidelibre-logo_300x300.jpg",
            "http://a1.twimg.com/profile_images/655119538/andbook_normal.png",
            "http://a3.twimg.com/profile_images/511790713/AG_normal.png",
            "http://a3.twimg.com/profile_images/956404323/androinica-avatar_normal.png",
            "http://a1.twimg.com/profile_images/909231146/Android_Biz_Man_normal.png",
            "http://a3.twimg.com/profile_images/121630227/Droid.jpg",
            "http://a1.twimg.com/profile_images/957149154/twitterhalf_normal.jpg",
            "http://a1.twimg.com/profile_images/97470808/icon_normal.png",
            "http://a3.twimg.com/profile_images/511790713/AG_normal.png",
            "http://a3.twimg.com/profile_images/956404323/androinica-avatar_normal.png",
            "http://a1.twimg.com/profile_images/909231146/Android_Biz_Man.png",
            "http://a3.twimg.com/profile_images/72774055/AndroidHomme-LOGO_normal.jpg",
            "http://a1.twimg.com/profile_images/349012784/android_logo_small_normal.jpg",
            "http://a1.twimg.com/profile_images/841338368/ea-twitter-icon_normal.png",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet.png",
            "http://a3.twimg.com/profile_images/670625317/aam-logo-v3-twitter_normal.png",
            "http://a3.twimg.com/profile_images/740897825/AndroidCast-350_normal.png",
            "http://a3.twimg.com/profile_images/121630227/Droid_normal.jpg",
            "http://a1.twimg.com/profile_images/957149154/twitterhalf_normal.jpg",
            "http://a1.twimg.com/profile_images/97470808/icon.png",
            "http://a3.twimg.com/profile_images/511790713/AG_normal.png",
            "http://a3.twimg.com/profile_images/956404323/androinica-avatar_normal.png",
            "http://a1.twimg.com/profile_images/909231146/Android_Biz_Man_normal.png",
            "http://a3.twimg.com/profile_images/72774055/AndroidHomme-LOGO_normal.jpg",
            "http://a1.twimg.com/profile_images/349012784/android_logo_small_normal.jpg",
            "http://a1.twimg.com/profile_images/841338368/ea-twitter-icon.png",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet_normal.png",
            "http://a1.twimg.com/profile_images/605536070/twitterProfilePhoto_normal.jpg",
            "http://a1.twimg.com/profile_images/850960042/elandroidelibre-logo_300x300_normal.jpg",
            "http://a1.twimg.com/profile_images/655119538/andbook_normal.png",
            "http://a3.twimg.com/profile_images/768060227/ap4u_normal.jpg",
            "http://a1.twimg.com/profile_images/74724754/android_logo.png",
            "http://a3.twimg.com/profile_images/681537837/SmallAvatarx150_normal.png",
            "http://a1.twimg.com/profile_images/63737974/2008-11-06_1637_normal.png",
            "http://a3.twimg.com/profile_images/548410609/icon_8_73_normal.png",
            "http://a1.twimg.com/profile_images/612232882/nexusoneavatar_normal.jpg",
            "http://a1.twimg.com/profile_images/213722080/Bugdroid-phone_normal.png",
            "http://a1.twimg.com/profile_images/645523828/OT_icon_090918_android.png",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet_normal.png",
            "http://a1.twimg.com/profile_images/605536070/twitterProfilePhoto_normal.jpg",
            "http://a1.twimg.com/profile_images/850960042/elandroidelibre-logo_300x300_normal.jpg",
            "http://a1.twimg.com/profile_images/655119538/andbook.png",
            "http://a3.twimg.com/profile_images/511790713/AG_normal.png",
            "http://a3.twimg.com/profile_images/956404323/androinica-avatar_normal.png",
            "http://a1.twimg.com/profile_images/909231146/Android_Biz_Man_normal.png",
            "http://a3.twimg.com/profile_images/72774055/AndroidHomme-LOGO_normal.jpg",
            "http://a1.twimg.com/profile_images/349012784/android_logo_small_normal.jpg",
            "http://a1.twimg.com/profile_images/841338368/ea-twitter-icon.png",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet_normal.png",
            "http://a1.twimg.com/profile_images/605536070/twitterProfilePhoto_normal.jpg",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet_normal.png",
            "http://a1.twimg.com/profile_images/605536070/twitterProfilePhoto.jpg",
            "http://a1.twimg.com/profile_images/850960042/elandroidelibre-logo_300x300_normal.jpg",
            "http://a1.twimg.com/profile_images/655119538/andbook_normal.png",
            "http://a3.twimg.com/profile_images/511790713/AG_normal.png",
            "http://a3.twimg.com/profile_images/956404323/androinica-avatar_normal.png",
            "http://a1.twimg.com/profile_images/909231146/Android_Biz_Man_normal.png",
            "http://a3.twimg.com/profile_images/121630227/Droid_normal.jpg",
            "http://a1.twimg.com/profile_images/957149154/twitterhalf.jpg",
            "http://a1.twimg.com/profile_images/97470808/icon_normal.png",
            "http://a3.twimg.com/profile_images/511790713/AG_normal.png",
            "http://a3.twimg.com/profile_images/956404323/androinica-avatar_normal.png",
            "http://a1.twimg.com/profile_images/909231146/Android_Biz_Man_normal.png",
            "http://a3.twimg.com/profile_images/72774055/AndroidHomme-LOGO_normal.jpg",
            "http://a1.twimg.com/profile_images/349012784/android_logo_small.jpg",
            "http://a1.twimg.com/profile_images/841338368/ea-twitter-icon_normal.png",
            "http://a3.twimg.com/profile_images/64827025/android-wallpaper6_2560x160_normal.png",
            "http://a3.twimg.com/profile_images/77641093/AndroidPlanet_normal.png"
    };

    ListView lv;    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv= (ListView) findViewById(R.id.lv);
        lv.setAdapter(new LazyAdapter(this,mStrings));
    }
}

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activity_main.xml中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >
    <ListView
        android:id="@+id/lv"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="#000000"
        android:focusableInTouchMode="false"
        android:listSelector="@android:color/transparent"
        android:layout_weight="2.0"
        android:divider="#000000"
        android:headerDividersEnabled="false"
        android:footerDividersEnabled="false"
        android:dividerHeight="8dp"
        android:drawSelectorOnTop="false"
        />
</RelativeLayout>

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LazyAdapter.java

public class LazyAdapter extends BaseAdapter {
    private Activity activity;
    private String data[];
    private LayoutInflater inflater=null;
    public ImageLoader imageLoader; 
    DisplayImageOptions options;
    public LazyAdapter(Activity a, String[] d) {
        activity = a;
        data=d;
        inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        File cacheDir = StorageUtils.getOwnCacheDirectory(a, "MyFolderCache");

        // Get singletone instance of ImageLoader
        imageLoader = ImageLoader.getInstance();
        // Create configuration for ImageLoader (all options are optional)
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(a)
              // You can pass your own memory cache implementation
             .discCacheExtraOptions(1024, 1024, CompressFormat.PNG, 100)
             .discCache(new UnlimitedDiscCache(cacheDir)) // You can pass your own disc cache implementation
             .discCacheFileNameGenerator(new HashCodeFileNameGenerator())
             .enableLogging()
             .build();
        // Initialize ImageLoader with created configuration. Do it once.
        imageLoader.init(config);
        //imageLoader.init(ImageLoaderConfiguration.createDefault(a));
        // imageLoader=new ImageLoader(activity.getApplicationContext());
        options = new DisplayImageOptions.Builder()
             .showStubImage(R.drawable.ic_launcher)
             .cacheInMemory()
             .cacheOnDisc()
             .displayer(new RoundedBitmapDisplayer(20))
             .build();
    }

    public int getCount() {
        return data.length;
    }

    public Object getItem(int position) {
        return position;
    }

    public long getItemId(int position) {
        return position;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;
        ViewHolder vh = new ViewHolder();;
        if(convertView==null)
        {

            vi = inflater.inflate(R.layout.row, null);   
            vh.iv=(ImageView)vi.findViewById(R.id.ivv); 
            vh.pb= (ProgressBar)vi.findViewById(R.id.pb); 
            vh.tv = (TextView) vi.findViewById(R.id.textView1);
            vh.tv1= (TextView) vi.findViewById(R.id.textView2);
        }
        vh.tv.setText("Image in postion =");
        vh.tv1.setText(""+position);
        display(vh.iv, data[position], vh.pb);
        //imageLoader.displayImage(data.get(position).toString(), image,options);
        return vi;
    }

    public void display(ImageView img, String url, final ProgressBar spinner)
    {
        imageLoader.displayImage(url, img, options, new ImageLoadingListener() {
            @Override
            public void onLoadingStarted(String imageUri, View view) {
                spinner.setVisibility(View.VISIBLE);
            }
            @Override
            public void onLoadingFailed(String imageUri, View view, FailReason failReason) {
                spinner.setVisibility(View.GONE);
            }
            @Override
            public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
            spinner.setVisibility(View.GONE);
            }
            @Override
            public void onLoadingCancelled(String imageUri, View view) {

            }
        });
    }

    public static class ViewHolder
    {
        ImageView iv;
        TextView tv,tv1;
        ProgressBar pb;
    }
}

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row.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:src="@drawable/ic_launcher" />
    <ProgressBar 
        android:id="@+id/pb"
        android:layout_centerInParent="true"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/textView2"
        android:layout_alignParentLeft="true"
        android:layout_marginBottom="21dp"
        android:layout_marginLeft="31dp"
        android:text="TextView" />
    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_alignParentBottom="true"
        android:text="TextView" />
</RelativeLayout>

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在清单中添加权限

 <uses-permission android:name="android.permission.INTERNET"/>

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在此输入图像描述

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