本文介绍了从远程URL下载图像的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
目前我正在开发包含其中显示YouTube视频链接列表视图中的Android应用程序。该应用程序从服务器作为JSON中获取数据。现在，我想为这些视频从这个子域显示缩略图 - http://img.youtube.com/vi/
但图像没有在列表视图中显示出来。
下面是code项目：
1 - canticlesActivity.java
包com.shadatv.shada;进口的java.io.File;
进口java.io.FileOutputStream中;
进口java.io.IOException异常;
进口的java.io.InputStream;
进口java.net.HttpURLConnection中;
进口的java.net.URL;
进口的java.util.ArrayList;
进口的java.util.HashMap;进口org.apache.http.HttpEntity;
进口org.apache.http.Htt presponse;
进口org.apache.http.client.ClientProtocolException;
进口org.apache.http.client.HttpClient;
进口org.apache.http.client.methods.HttpGet;
进口org.apache.http.impl.client.DefaultHttpClient;
进口org.apache.http.util.EntityUtils;
进口org.json.JSONArray;
进口org.json.JSONException;
进口org.json.JSONObject;进口android.app.ListActivity;
进口android.os.AsyncTask;
进口android.os.Bundle;
进口android.os.Environment;
进口android.util.Log;
进口android.widget.ListAdapter;
进口android.widget.SimpleAdapter;
进口android.widget.TextView;
进口android.widget.Toast;公共类canticlesActivity扩展ListActivity { TextView的httpStuff;
HttpClient的客户端;
JSONArray canticles;
字符串picpath =http://img.youtube.com/vi/; 文件SD卡= Environment.getExternalStorageDirectory（）; 文件shadaRoot =新的文件（sdcard.getAbsolutePath（）+/ shada_Folder）; 私有静态最后弦乐CA_NAME =CA_NAME;
私有静态最后弦乐CA_LINK =ca_link;
私有静态最后弦乐CA_IMG =ca_img;
私有静态最终字符串URL =http://dt-works.com/ags/shadatv/canticles/android_data; ArrayList的＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT; canticlesList; @覆盖
公共无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.canticles）; httpStuff =（的TextView）findViewById（R.id.textView1）;
客户端=新DefaultHttpClient（）;
新阅读（）执行（）;
} 公共JSONArray allCanticles（）抛出ClientProtocolException，IOException异常，JSONException {
StringBuilder的URL =新的StringBuilder（URL）; HTTPGET GET =新HTTPGET（url.toString（））;
HTT presponse R = client.execute（获取）;
。INT状态= r.getStatusLine（）的getStatus code（）; 如果（状态== 200）{
HttpEntity E = r.getEntity（）;
字符串数据= EntityUtils.toString（E）;
JSONArray canticles =新JSONArray（数据）;
返回canticles; }其他{
Toast.makeText（getBaseContext（），错误，Toast.LENGTH_SHORT）.show（）;
返回null;
}
} 公共无效downloadImage（字符串fileURL）{
尝试{
// Toast.makeText（getBaseContext（），baaad，Toast.LENGTH_SHORT）.show（）;
串finlpth =;
finlpth = picpath + fileURL +/2.jpg
shadaRoot.mkdirs（）; URL U =新的URL（finlpth）;
HttpURLConnection的C =（HttpURLConnection类）u.openConnection（）;
c.setRequestMethod（GET）;
c.setDoOutput（真）;
c.connect（）; 文件DownloadedFile =新的文件（shadaRoot，fileURL +.JPG）;
//如果（！outfile.exists（））
FileOutputStream中F =新的FileOutputStream（DownloadedFile）; 在的InputStream = c.getInputStream（）; 字节[]缓冲区=新的字节[1024];
INT LEN1 = 0;
而（（LEN1 = in.read（缓冲液））大于0）{
f.write（缓冲液，0，LEN1）;
} f.close（）; }赶上（例外五）{
Log.d（下载，e.getMessage（））;
}
} 公共类读取扩展的AsyncTask＆LT;字符串，字符串，字符串＆GT; { @覆盖
保护字符串doInBackground（字符串... PARAMS）{ canticlesList =新的ArrayList＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;（）;
尝试{
canticles = allCanticles（）;
的for（int i = 0; I＆LT; canticles.length（）;我++）{
JSONObject的颂歌= canticles.getJSONObject（I）
字符串CA_NAME = canticle.getString（CA_NAME）;
字符串ca_link = canticle.getString（CA_LINK）; downloadImage（ca_link）; HashMap的＆LT;字符串，字符串＆GT;地图=新的HashMap＆LT;字符串，字符串＆GT;（）;
map.put（CA_NAME，CA_NAME）;
map.put（CA_LINK，ca_link）;
map.put（CA_IMG，ca_link +.JPG）;
canticlesList.add（地图）;
} }赶上（ClientProtocolException E）{
e.printStackTrace（）;
}赶上（IOException异常五）{
e.printStackTrace（）;
}赶上（JSONException E）{
e.printStackTrace（）;
}
返回null;
} @覆盖
保护无效onPostExecute（字符串结果）{ ListAdapter适配器=新SimpleAdapter（canticlesActivity.this，
canticlesList，R.layout.list_item，
新的String [] {CA_NAME，CA_LINK，CA_IMG}，
新的INT [] {R.id.ca_name，R.id.ca_link，R.id.ca_img}）;
setListAdapter（适配器）; }
}
}
2 - list_item.xml
＆LT;？XML版本=1.0编码=UTF-8＆GT？;
＆LT; LinearLayout中的xmlns：机器人=http://schemas.android.com/apk/res/android
机器人：layout_width =FILL_PARENT
机器人：layout_height =WRAP_CONTENT
机器人：背景=@绘制/ list_selector
机器人：方向=横向＆GT; ＆LT;！ - 产品ID（PID） - 会被隐藏 - 用于传递给其他活动 - ＆GT; ＆LT; ImageView的
机器人：ID =@ + ID / ca_img
机器人：layout_width =50dip
机器人：layout_height =50dip
机器人：contentDescription =@字符串/ DESC
/＆GT; ＆LT;的TextView
机器人：ID =@ + ID / CA_NAME
机器人：layout_width =FILL_PARENT
机器人：layout_height =WRAP_CONTENT
/＆GT; ＆LT;！ - 名称标签 - ＆GT;
＆LT;的TextView
机器人：ID =@ + ID / ca_link
机器人：layout_width =FILL_PARENT
机器人：layout_height =WRAP_CONTENT
机器人：paddingTop =6DIP
机器人：paddingLeft =6DIP
机器人：TEXTSIZE =17sp
机器人：文字样式=大胆
机器人：知名度=水涨船高/＆GT;＆LT; / LinearLayout中＆GT;
解决方案
您可以使用
它使用非常简单 - imageLoader.displayImage（imageUri，ImageView的）;
Currently I am developing an Android app containing a list view which displays links for Youtube videos. The application gets its data from the server as JSON. Now I am trying to display thumbnails for these video from this subdomain - http://img.youtube.com/vi/.
But the images don't show up in the list view.
Here is the code for the project :
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>
解决方案
You can use UniversalImageLoaderit very simple for using -imageLoader.displayImage(imageUri, imageView);
这篇关于从远程URL下载图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！