我在我的一个应用程序中使用毕加索来下载大量图像以供将来使用,因为登录后应用程序将完全离线模式。
因此,成功登录后,我试图下载带有进度的 AsyncTask 中的图像
为了实现这个目标,我编写了以下代码来下载一堆图像
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import com.squareup.picasso.Picasso;
public class CacheActivity extends Activity {
    int size = 0;
    final List<String> urls = new ArrayList<String>();
    int totalImageSize;
    static Picasso picasso;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_cache);
        Collections.addAll(urls, Data.URLS);
        Collections.addAll(urls, Data.URLS);
        Collections.addAll(urls, Data.URLS);
        totalImageSize = urls.size();
        picasso = Picasso.with(CacheActivity.this);
        picasso.setDebugging(true);
        new TestTask().execute();
    }
    public class TestTask extends AsyncTask<Void, Integer, Void>
    {
        ProgressDialog dialog;
        @Override
        protected void onPreExecute() {
            dialog = new ProgressDialog(CacheActivity.this);
            dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            dialog.setMax(totalImageSize);
            dialog.setMessage("1 - 100");
            dialog.setCanceledOnTouchOutside(false);
            dialog.show();
        }
        @Override
        protected Void doInBackground(Void... params) {
            for (Iterator iterator = urls.iterator(); iterator.hasNext();) {
                final String url = (String) iterator.next();
                try {
                    picasso.load(url).get();
                    } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                size = size + 1;
                publishProgress(size);
            System.out.println("CacheActivity.TestTask.doInBackground()");
            }
            return null;
        }
        @Override
        protected void onPostExecute(Void result) {
            dialog.dismiss();
        }
    }
}
但是当我运行应用程序时,我收到以下错误
07-30 12:55:42.334: W/System.err(2369): java.lang.NullPointerException: key == null
07-30 12:55:42.334: W/System.err(2369):     at com.squareup.picasso.LruCache.get(LruCache.java:50)
07-30 12:55:42.334: W/System.err(2369):     at com.squareup.picasso.BitmapHunter.hunt(BitmapHunter.java:101)
07-30 12:55:42.334: W/System.err(2369):     at com.squareup.picasso.RequestBuilder.get(RequestBuilder.java:305)
07-30 12:55:42.344: W/System.err(2369):     at com.example.picasso.CacheActivity$TestTask.doInBackground(CacheActivity.java:61)
07-30 12:55:42.344: W/System.err(2369):     at com.example.picasso.CacheActivity$TestTask.doInBackground(CacheActivity.java:1)
07-30 12:55:42.344: W/System.err(2369):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
07-30 12:55:42.344: W/System.err(2369):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-30 12:55:42.344: W/System.err(2369):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-30 12:55:42.344: W/System.err(2369):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
07-30 12:55:42.344: W/System.err(2369):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-30 12:55:42.344: W/System.err(2369):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-30 12:55:42.344: W/System.err(2369):     at java.lang.Thread.run(Thread.java:856)
07-30 12:55:42.334: W/System.err(2369): java.lang.NullPointerException: key == null
07-30 12:55:42.334: W/System.err(2369):     at com.squareup.picasso.LruCache.get(LruCache.java:50)
07-30 12:55:42.334: W/System.err(2369):     at com.squareup.picasso.BitmapHunter.hunt(BitmapHunter.java:101)
07-30 12:55:42.334: W/System.err(2369):     at com.squareup.picasso.RequestBuilder.get(RequestBuilder.java:305)
07-30 12:55:42.344: W/System.err(2369):     at com.example.picasso.CacheActivity$TestTask.doInBackground(CacheActivity.java:61)
07-30 12:55:42.344: W/System.err(2369):     at com.example.picasso.CacheActivity$TestTask.doInBackground(CacheActivity.java:1)
07-30 12:55:42.344: W/System.err(2369):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
07-30 12:55:42.344: W/System.err(2369):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-30 12:55:42.344: W/System.err(2369):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-30 12:55:42.344: W/System.err(2369):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
07-30 12:55:42.344: W/System.err(2369):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-30 12:55:42.344: W/System.err(2369):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-30 12:55:42.344: W/System.err(2369):     at java.lang.Thread.run(Thread.java:856)
有什么我做错了吗?