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我正在開發Android應用程序，以便從所有朋友處下載圖片。我成功地讓我的應用程序登錄。現在，我需要解析一個JSON並下載一些圖片。這裏來源：使用AsyncTask下載文件時發生崩潰
FacebookPicDownloader（的AsyncTask下載所有圖片）：
public class FacebookPicDownloader extends AsyncTask <String, Integer, Integer>{
Context context;
private final int MAX_BUFFER_SIZE = 2048;
String id;
int length;
public FacebookPicDownloader (Context context){
this.context = context;
}
//http://graph.facebook.com/ + userid + /picture?type=large to download the photos
@Override
protected Integer doInBackground(String... params) {
for (int i=0; i<params.length; i++){
try {
URL mUrl = new URL("http://graph.facebook.com/" + params[i] + "/picture?type=large");
HttpURLConnection connection = (HttpURLConnection) mUrl.openConnection();
connection.connect();
length = connection.getContentLength();
int downloaded = 0;
File file = new File ("/sdcard/syncro/");
if (!file.exists() || !file.isDirectory()){
file.mkdir();
}
id = params[0];
file = new File ("/sdcard/syncro/" + id);
FileOutputStream fos = new FileOutputStream (file);
//Start downloading
InputStream stream = connection.getInputStream();
byte [] buffer = new byte [(length < MAX_BUFFER_SIZE) ? length : MAX_BUFFER_SIZE];
int read;
while ((read=stream.read(buffer)) != -1){
fos.write(buffer, 0, read);
downloaded += read;
}
fos.close();
} catch (Exception e){
return 2;
}
}
return 1;
}
Manager.java，另一個的AsyncTask調用FacebookPicDownloader
import java.util.ArrayList;
import org.json.*;
import com.gnufabio.syncro.util.Util;
import android.app.ProgressDialog;
import android.content.Context;
import android.database.Cursor;
import android.os.AsyncTask;
import android.provider.ContactsContract;
import android.util.Log;
import com.facebook.android.*;
import com.gnufabio.syncro.util.*;
public class Manager extends AsyncTask<String, Integer, Integer>{
Context context;
Facebook facebook;
ProgressDialog dialog;
public void doStuff(Facebook facebook, Context context, String ... params){
this.context = context;
this.facebook = facebook;
this.execute(params);
}
@Override
protected void onPreExecute(){
dialog = ProgressDialog.show(context, "Wait" , " Loading. Please wait ... ", true);
dialog.setCancelable(false);
}
@Override
protected Integer doInBackground(String... params) {
String friendlist;
try {
friendlist = facebook.request("me/friends");
FileWriterThread filewriter = new FileWriterThread();
filewriter.writeFile(friendlist, "/sdcard/syncro/friends");
} catch (Exception e) {
friendlist = "";
}
String previous = "[NONE]";
ArrayList validContacts = new ArrayList<String>();
Cursor nameCur = context.getContentResolver().query(ContactsContract.Data.CONTENT_URI, null, ContactsContract.Data.MIMETYPE + " = ?", new String[] { ContactsContract.CommonDataKinds.StructuredName.CONTENT_ITEM_TYPE }, ContactsContract.CommonDataKinds.StructuredName.GIVEN_NAME);
while (nameCur.moveToNext()) {
String display = nameCur.getString(nameCur.getColumnIndex(ContactsContract.CommonDataKinds.StructuredName.DISPLAY_NAME));
if (display != null && !(display.contains(previous) || display.equalsIgnoreCase(previous)) && display.contains(" ")){
Log.d("SYNCRO", "Valid contact found: " + display);
validContacts.add(display);
previous = display;
}
}
nameCur.close();
try {
ArrayList idToDownload = new ArrayList <String>();
JSONArray jFriendList = new JSONArray(new JSONObject(friendlist).getString("data"));
for (int i = 0; i < jFriendList.length(); i++){
JSONObject jFriend = jFriendList.getJSONObject(i);
for (int y = 0; y < validContacts.toArray().length; y++){
if (jFriend.getString("name").equals((String)(validContacts.get(y)))){
String id = jFriend.getString("id");
Log.d("SYNCRO", "Adding pic for id \"" + id + "\"");
idToDowload.add(id);
}
}
}
FacebookPicDownloader downloader = new FacebookPicDownloader(context);
downloader.execute((String[]) idToDownload.toArray());
} catch (JSONException e) {
Log.d("SYNCRO", e.getMessage());
}
return null;
}
@Override
protected void onPostExecute(Integer result){
dialog.dismiss();
}
}
的問題是，它只下載第一張照片，然後應用程序崩潰...在這裏logcat：
D/szipinf (7785): Initializing inflate state
E/AndroidRuntime(7735): FATAL EXCEPTION: AsyncTask #1
E/AndroidRuntime(7735): java.lang.RuntimeException: An error occured while executing doInBackground()
E/AndroidRuntime(7735): at android.os.AsyncTask$3.done(AsyncTask.java:200)
E/AndroidRuntime(7735): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
E/AndroidRuntime(7735): at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
E/AndroidRuntime(7735): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
E/AndroidRuntime(7735): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
E/AndroidRuntime(7735): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
E/AndroidRuntime(7735): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
E/AndroidRuntime(7735): at java.lang.Thread.run(Thread.java:1019)
E/AndroidRuntime(7735): Caused by: java.lang.ClassCastException: [Ljava.lang.Object;
E/AndroidRuntime(7735): at com.gnufabio.syncro.Manager.doInBackground(Manager.java:78)
E/AndroidRuntime(7735): at com.gnufabio.syncro.Manager.doInBackground(Manager.java:1)
E/AndroidRuntime(7735): at android.os.AsyncTask$2.call(AsyncTask.java:185)
E/AndroidRuntime(7735): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
E/AndroidRuntime(7735): ... 4 more W/ActivityManager( 541): Force finishing activity com.gnufabio.syncro/.SuperSyncronizerActivity D/szipinf (7797): Initializing inflate state D/szipinf (7797): Initializing zlib to inflate D/dalvikvm(7797): GC_CONCURRENT freed 224K, 44% free 3519K/6215K, external 0K/0K, paused 3ms+3ms
E/WindowManager(7735): Activity com.gnufabio.syncro.SuperSyncronizerActivity has leaked window [email protected] that was originally added here
E/WindowManager(7735): android.view.WindowLeaked: Activity com.gnufabio.syncro.SuperSyncronizerActivity has leaked window com.android.internal.policy.impl.Phone[email protected] that was originally added here
E/WindowManager(7735): at android.view.ViewRoot.<init>(ViewRoot.java:260)
E/WindowManager(7735): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
E/WindowManager(7735): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
E/WindowManager(7735): at android.view.Window$LocalWindowManager.addView(Window.java:424)
E/WindowManager(7735): at android.app.Dialog.show(Dialog.java:241)
E/WindowManager(7735): at android.app.ProgressDialog.show(ProgressDialog.java:110)
E/WindowManager(7735): at android.app.ProgressDialog.show(ProgressDialog.java:93)
E/WindowManager(7735): at com.gnufabio.syncro.Manager.onPreExecute(Manager.java:36)
E/WindowManager(7735): at android.os.AsyncTask.execute(AsyncTask.java:391)
E/WindowManager(7735): at com.gnufabio.syncro.Manager.doStuff(Manager.java:31)
E/WindowManager(7735): at com.gnufabio.syncro.SuperSyncronizerActivity$2.onClick(SuperSyncronizerActivity.java:73)
E/WindowManager(7735): at android.view.View.performClick(View.java:2486)
E/WindowManager(7735): at android.view.View$PerformClick.run(View.java:9130)
E/WindowManager(7735): at android.os.Handler.handleCallback(Handler.java:587)
E/WindowManager(7735): at android.os.Handler.dispatchMessage(Handler.java:92)
E/WindowManager(7735): at android.os.Looper.loop(Looper.java:130)
E/WindowManager(7735): at android.app.ActivityThread.main(ActivityThread.java:3694)
E/WindowManager(7735): at java.lang.reflect.Method.invokeNative(Native Method)
E/WindowManager(7735): at java.lang.reflect.Method.invoke(Method.java:507)
E/WindowManager(7735): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
E/WindowManager(7735): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
E/WindowManager(7735): at dalvik.system.NativeStart.main(Native Method) D/dalvikvm(7797): GC_CONCURRENT freed 171K, 41% free 3888K/6535K, external 0K/0K, paused 3ms+4ms
感謝任何人都會幫助我。
你得到一個ClassCastException。嘗試調試並檢查。你可能會得到一個線索。引起：java.lang.ClassCastException：[Ljava.lang.Object; E/AndroidRuntime（7735）：在com.gnufabio.syncro.Manager.doInBackground（Manager.java:78） –
嗨， 這有點令人困惑，因爲你說它適用於第一張圖片。 也許這個ID有什麼問題？ 你傳遞一個字符串數組來啓動facebook下載器，它包含一個ID列表 - 也許做一個快速調試器檢查，或者只是一個打印出來，看看所有的ID是否實際ID和一致？ URL mUrl = new URL（「http://graph.facebook.com/」+ params [i] +「/ picture？type = large」）; 有可能類轉換異常正在發生，因爲您試圖將輸入流轉換爲文件並將其保存，但輸入流並未給出您所期望的 – ryvianstyron