如何从服务器数据库下载多个图像？ [英] How to download multiple images from server database?
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问题描述
在我的应用程序中，我想从数据库下载所有图像。
对于单个图像，代码工作正常。对于多个图像，显示内存不足错误。
这是我的代码：
In my application, I want to download all images from the database.
For single image, the code is working fine. For multiple images, out of memory error is showing.
Here is my code:
public class GalleryFragment extends Fragment {
ProgressBar progressBar;
TextView progressText;
JSONParser jsonParser = new JSONParser();
private static String url_download_photo = Global.url+"/clubs/download_photo.php";
private static final String TAG_SUCCESS = "success";
private static final String TAG_CLUBS = "clubs";
private static final String TAG_PHOTO = "photo";
JSONArray clubs = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_gallery, container, false);
progressText = (TextView) rootView.findViewById(R.id.textView1);
progressBar = (ProgressBar) rootView.findViewById( R.id.progressBar1);
new DownloadPhoto().execute();
return rootView;
}
class DownloadPhoto extends AsyncTask<String, String, String> {
protected String doInBackground(String... args) {
Log.v("DownloadPhoto","doInBackground");
try {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("club_id", ClubActivity.club_id));
JSONObject json = jsonParser.makeHttpRequest(url_download_photo,"GET", params);
Log.d("Download Image", json.toString());
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
getActivity().runOnUiThread(new Runnable() {
public void run() {
progressBar.setVisibility(View.VISIBLE);
}
});
clubs = json.getJSONArray(TAG_CLUBS);
progressBar.setMax(clubs.length());
for (int i = 0; i < clubs.length(); i++) {
JSONObject c = clubs.getJSONObject(i);
// Storing each json item in variable
String photo = c.getString(TAG_PHOTO);
progressBar.setProgress(i+1);
Log.v("Photo "+i,""+photo);
}
getActivity().runOnUiThread(new Runnable() {
public void run() {
progressBar.setVisibility(View.INVISIBLE);
}
});
}
else
{
}
} catch (JSONException e) {
problem();
e.printStackTrace();
}
catch(Exception e)
{
problem();
Log.v("Exception",""+e);
}
return null;
}
}
void problem()
{
getActivity().runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(getActivity(), "Something went wrong! Try again!",Toast.LENGTH_LONG).show();
progressBar.setVisibility(View.INVISIBLE);
progressText.setVisibility(View.INVISIBLE);
}
});
}
}
download_photo.php
download_photo.php
<?php
// array for JSON response
$response = array();
// include db connect class
require_once __DIR__ . '/db_connect.php';
// connecting to db
$db = new DB_CONNECT();
// check for post data
if (isset($_GET["club_id"])) {
$club_id = $_GET['club_id'];
$result = mysql_query("SELECT photo FROM gallery WHERE club_id = '$club_id'") or die(mysql_error());
if (!empty($result)) {
// check for empty result
if (mysql_num_rows($result) > 0) {
$response["clubs"] = array();
while ($row = mysql_fetch_array($result)) {
$clubs = array();
$clubs["photo"] = $row["photo"];
array_push($response["clubs"], $clubs);
}
// success
$response["success"] = 1;
echo json_encode($response);
}
else {
$response["success"] = 0;
$response["message"] = "Not found";
echo json_encode($response);
}
}
else {
$response["success"] = 0;
$response["message"] = "Not found";
echo json_encode($response);
}
}
else {
// required field is missing
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";
echo json_encode($response);
}
?>
错误
Error
07-01 17:56:40.360: E/dalvikvm-heap(6962): Out of memory on a 1490086-byte allocation.
07-01 17:56:40.400: E/AndroidRuntime(6962): FATAL EXCEPTION: AsyncTask #1
07-01 17:56:40.400: E/AndroidRuntime(6962): Process: com.daceshine.clubs, PID: 6962
07-01 17:56:40.400: E/AndroidRuntime(6962): java.lang.RuntimeException: An error occured while executing doInBackground()
07-01 17:56:40.400: E/AndroidRuntime(6962): at android.os.AsyncTask$3.done(AsyncTask.java:300)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.util.concurrent.FutureTask.run(FutureTask.java:242)
07-01 17:56:40.400: E/AndroidRuntime(6962): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.lang.Thread.run(Thread.java:841)
07-01 17:56:40.400: E/AndroidRuntime(6962): Caused by: java.lang.OutOfMemoryError
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.lang.AbstractStringBuilder.enlargeBuffer(AbstractStringBuilder.java:94)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.lang.AbstractStringBuilder.append0(AbstractStringBuilder.java:132)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.lang.StringBuilder.append(StringBuilder.java:124)
07-01 17:56:40.400: E/AndroidRuntime(6962): at org.json.JSONStringer.string(JSONStringer.java:344)
07-01 17:56:40.400: E/AndroidRuntime(6962): at org.json.JSONStringer.value(JSONStringer.java:252)
07-01 17:56:40.400: E/AndroidRuntime(6962): at org.json.JSONObject.writeTo(JSONObject.java:672)
07-01 17:56:40.400: E/AndroidRuntime(6962): at org.json.JSONStringer.value(JSONStringer.java:237)
07-01 17:56:40.400: E/AndroidRuntime(6962): at org.json.JSONArray.writeTo(JSONArray.java:602)
07-01 17:56:40.400: E/AndroidRuntime(6962): at org.json.JSONStringer.value(JSONStringer.java:233)
07-01 17:56:40.400: E/AndroidRuntime(6962): at org.json.JSONObject.writeTo(JSONObject.java:672)
07-01 17:56:40.400: E/AndroidRuntime(6962): at org.json.JSONObject.toString(JSONObject.java:641)
07-01 17:56:40.400: E/AndroidRuntime(6962): at com.daceshine.clubs.GalleryFragment$DownloadPhoto.doInBackground(GalleryFragment.java:71)
07-01 17:56:40.400: E/AndroidRuntime(6962): at com.daceshine.clubs.GalleryFragment$DownloadPhoto.doInBackground(GalleryFragment.java:1)
07-01 17:56:40.400: E/AndroidRuntime(6962): at android.os.AsyncTask$2.call(AsyncTask.java:288)
07-01 17:56:40.400: E/AndroidRuntime(6962): at java.util.concurrent.FutureTask.run(FutureTask.java:237)
07-01 17:56:40.400: E/AndroidRuntime(6962): ... 4 more
我应该更改什么？有没有其他方法可以做到这一点？
What should I change? Is there any other method for doing it?
推荐答案
response = array（）;
//包括db connect class
require_once __DIR__。 /db_connect.php;
//连接到db
response = array(); // include db connect class require_once __DIR__ . '/db_connect.php'; // connecting to db
db = new DB_CONNECT（）;
//检查发布数据
if（isset（
db = new DB_CONNECT(); // check for post data if (isset(
_GET [club_id]））{
_GET["club_id"])) {
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