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目前我正在开发一个包含列表视图的 Android 应用程序,其中显示 Youtube 视频的链接。应用程序以 JSON 格式从服务器获取其数据。现在我正在尝试显示来自该子域的这些视频的缩略图 -http://img.youtube.com/vi/ .

但图像不会显示在列表视图中。

这是该项目的代码:

1 - canticlesActivity.java

package com.shadatv.shada;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.widget.ListAdapter;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class canticlesActivity extends ListActivity {

    TextView httpStuff;
    HttpClient client;
    JSONArray canticles;
    String picpath = "http://img.youtube.com/vi/";

    File sdcard = Environment.getExternalStorageDirectory();

    File shadaRoot = new File(sdcard.getAbsolutePath() + "/shada_Folder");

    private static final String CA_NAME = "ca_name";
    private static final String CA_LINK = "ca_link";
    private static final String CA_IMG = "ca_img";
    private static final String URL = "http://dt-works.com/ags/shadatv/canticles/android_data";

    ArrayList<HashMap<String, String>> canticlesList;



    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.canticles);

        httpStuff = (TextView) findViewById(R.id.textView1);
        client = new DefaultHttpClient();
        new Read().execute();
    }

    public JSONArray allCanticles() throws ClientProtocolException, IOException, JSONException {
        StringBuilder url = new StringBuilder(URL);

        HttpGet get = new HttpGet(url.toString());
        HttpResponse r = client.execute(get);
        int status = r.getStatusLine().getStatusCode();

        if (status == 200) {
            HttpEntity e = r.getEntity();
            String data = EntityUtils.toString(e);
            JSONArray canticles = new JSONArray(data);          
            return canticles;

        } else {
            Toast.makeText(getBaseContext(), "error", Toast.LENGTH_SHORT).show();
            return null;
        }
    }

    public void downloadImage(String fileURL) {
        try {
//          Toast.makeText(getBaseContext(), "baaad", Toast.LENGTH_SHORT).show();
            String finlpth = "";
            finlpth = picpath + fileURL + "/2.jpg";
            shadaRoot.mkdirs();

            URL u = new URL(finlpth);
            HttpURLConnection c = (HttpURLConnection) u.openConnection();
            c.setRequestMethod("GET");
            c.setDoOutput(true);
            c.connect();

            File DownloadedFile = new File(shadaRoot, fileURL + ".jpg");
            // if(!outfile.exists())
            FileOutputStream f = new FileOutputStream(DownloadedFile);

            InputStream in = c.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = in.read(buffer)) > 0) {
                f.write(buffer, 0, len1);
            }

            f.close();

        } catch (Exception e) {
            Log.d("Downloader", e.getMessage());
        }
    }

    public class Read extends AsyncTask<String, String, String>{

        @Override
        protected String doInBackground(String... params) {

            canticlesList = new ArrayList<HashMap<String, String>>();
            try {
                canticles = allCanticles();
                for (int i = 0; i < canticles.length(); i++) {
                    JSONObject canticle = canticles.getJSONObject(i);
                    String ca_name = canticle.getString(CA_NAME);
                    String ca_link = canticle.getString(CA_LINK);                   

                    downloadImage(ca_link);

                    HashMap<String, String> map = new HashMap<String, String>();                                        
                    map.put(CA_NAME, ca_name);
                    map.put(CA_LINK, ca_link);
                    map.put(CA_IMG, ca_link + ".jpg");
                    canticlesList.add(map);                                                     
                }

            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String result) {

            ListAdapter adapter = new SimpleAdapter(canticlesActivity.this, 
                                                    canticlesList,R.layout.list_item, 
                                                    new String[] {CA_NAME, CA_LINK, CA_IMG},
                                                    new int[] {R.id.ca_name, R.id.ca_link, R.id.ca_img});
            setListAdapter(adapter);

        }       
    }
}

2 - list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/list_selector"
    android:orientation="horizontal" >

    <!-- Product id (pid) - will be HIDDEN - used to pass to other activity -->

    <ImageView
        android:id="@+id/ca_img"
        android:layout_width="50dip"
        android:layout_height="50dip"
        android:contentDescription="@string/desc"              
         />

    <TextView
        android:id="@+id/ca_name"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
         />

    <!-- Name Label -->
    <TextView
        android:id="@+id/ca_link"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingTop="6dip"
        android:paddingLeft="6dip"
        android:textSize="17sp"
        android:textStyle="bold"
        android:visibility="gone" />

</LinearLayout>
4

3 回答 3

1

您可以使用UniversalImageLoader ,它的使用非常简单 -imageLoader.displayImage(imageUri, imageView);

于 2013-02-25T12:24:45.910 回答
0

在 youtube JSON 数据中,整个视频信息将在 "entry" JSON 数组中。您正在为 Hashmap 中的所有整体创建相同的标签名称。如果您为所有条目提供相同的标签,那么它将显示最后一个条目图像。请将 TAG NAME 更改为 "map.put(CA_IMG+i, ca_link + ".jpg");" 我希望这个解决方案对您有所帮助。

于 2013-02-25T12:35:52.243 回答
0

下载图像然后在 ListView 中显示是不好的过程。因为想想如果你有超过 100 张图像,那么显示它需要更多时间。

现在我建议的优化是:在 ListView 中实现延迟加载图像的逻辑。

请参考以下示例:

  1. Fedor 的懒惰列表
  2. 通用图像加载器
  3. 诺沃达的 ImageLoader
于 2013-02-25T12:36:44.760 回答