目前我正在开发一个包含列表视图的Android应用，该列表视图显示Youtube视频的链接。应用程序从服务器获取其数据作为JSON。现在，我正尝试在此子域中显示这些视频的缩略图 - http://img.youtube.com/vi/。
但图像未显示在列表视图中。
以下是该项目的代码：
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>
答案 0 :(得分：1)
您可以使用UniversalImageLoader
它非常简单 - imageLoader.displayImage(imageUri, imageView);
答案 1 :(得分：0)
在youtube JSON数据中，整个视频信息将位于“入门”JSON数组中。您正在为Hashmap中的所有条目创建相同的标记名称。如果为所有条目指定相同的标记，则它将显示最后一个条目图像。请将标签名称更改为“map.put（CA_IMG + i，ca_link +”.jpg“）;” 我希望这个解决方案对你有所帮助。
答案 2 :(得分：0)
下载图像然后在ListView中显示是一个糟糕的过程。因为只要想想你是否有> 100张图像，那么显示它就需要更多时间。
现在我建议的优化是：在ListView中实现延迟加载图像的逻辑。
参考以下示例：