android - AsyncTaskダウンロード画像エラー

Question

Google Chart APIを使用して、アプリでグラフを作成しています。

私の場合、各チャートの画像をダウンロードする必要があります。これにはAsyncTaskを使用します。

ダウンロードプロセスを監視するには、[進行状況]ダイアログを使用します。しかし、このクラスのAsyncTaskでエラーが発生しました。

AsyncTaskの実行：

new loadChart(ChartAct.this,img).execute();

およびAsyncTaskのコード：

public class loadChart extends AsyncTask<Void, Void, Void> {
    private ImageView img;
    private Context con;
    private ProgressDialog dialog;

    public loadChart(Context context, ImageView img1) {
        this.img = img1;
        this.con = context;
    }

    @Override
    protected void onPreExecute() {
        dialog = ProgressDialog.show(con, "Connecting:",
                "Loading. Please wait...", true);
        super.onPreExecute();
    }

    @Override
    protected Void doInBackground(Void... params) {
        final Bitmap bitmap = DownloadImage();
        img.setImageBitmap(bitmap);
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        dialog.dismiss();
        super.onPostExecute(result);
    }

    private static InputStream OpenHttpConnection(String urlString)
            throws IOException {

        Log.d("palval", "OpenHttpConnection");
        InputStream in = null;
        int response = -1;

        URL url = new URL(urlString);
        URLConnection conn = url.openConnection();

        if (!(conn instanceof HttpURLConnection))
            throw new IOException("Not an HTTP connection");

        try {
            HttpURLConnection httpConn = (HttpURLConnection) conn;
            httpConn.setAllowUserInteraction(false);
            httpConn.setInstanceFollowRedirects(true);
            httpConn.setRequestMethod("GET");
            httpConn.connect();

            response = httpConn.getResponseCode();

            if (response == HttpURLConnection.HTTP_OK) {
                in = httpConn.getInputStream();
            }

            String res = Integer.toString(response);
        } catch (Exception ex) {
            throw new IOException("Error connecting");
        }
        return in;
    }

    public static Bitmap DownloadImage() {
        Log.d("palval", "DownloadImage");
        Bitmap bitmap = null;
        InputStream in = null;
        try {

            in = OpenHttpConnection("https://chart.googleapis.com/chart?chs=440x220&chd=t:60,40&cht=p3&chl=Hello|World");
            bitmap = BitmapFactory.decodeStream(in);
            in.close();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        return bitmap;
    }

}

エラー：

09-06 18:35:35.574: E/AndroidRuntime(2502): FATAL EXCEPTION: AsyncTask #1
09-06 18:35:35.574: E/AndroidRuntime(2502): java.lang.RuntimeException: An error occured while executing doInBackground()
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.os.AsyncTask$3.done(AsyncTask.java:278)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at java.lang.Thread.run(Thread.java:864)
09-06 18:35:35.574: E/AndroidRuntime(2502): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4132)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:723)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.view.View.requestLayout(View.java:12957)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.view.View.requestLayout(View.java:12957)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.view.View.requestLayout(View.java:12957)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.view.View.requestLayout(View.java:12957)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.view.View.requestLayout(View.java:12957)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.widget.ImageView.setImageDrawable(ImageView.java:362)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.widget.ImageView.setImageBitmap(ImageView.java:377)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at com.example.headache.loadChart.doInBackground(loadChart.java:37)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at com.example.headache.loadChart.doInBackground(loadChart.java:1)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at android.os.AsyncTask$2.call(AsyncTask.java:264)
09-06 18:35:35.574: E/AndroidRuntime(2502):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
09-06 18:35:35.574: E/AndroidRuntime(2502):     ... 5 more
09-06 18:35:36.055: E/WindowManager(2502): Activity com.example.headache.ChartAct has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40dd3b28 that was originally added here
09-06 18:35:36.055: E/WindowManager(2502): android.view.WindowLeaked: Activity com.example.headache.ChartAct has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40dd3b28 that was originally added here
09-06 18:35:36.055: E/WindowManager(2502):  at android.view.ViewRootImpl.<init>(ViewRootImpl.java:352)
09-06 18:35:36.055: E/WindowManager(2502):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:373)
09-06 18:35:36.055: E/WindowManager(2502):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:321)
09-06 18:35:36.055: E/WindowManager(2502):  at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:152)
09-06 18:35:36.055: E/WindowManager(2502):  at android.view.Window$LocalWindowManager.addView(Window.java:541)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.Dialog.show(Dialog.java:301)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.ProgressDialog.show(ProgressDialog.java:116)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.ProgressDialog.show(ProgressDialog.java:99)
09-06 18:35:36.055: E/WindowManager(2502):  at com.example.headache.loadChart.onPreExecute(loadChart.java:29)
09-06 18:35:36.055: E/WindowManager(2502):  at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:561)
09-06 18:35:36.055: E/WindowManager(2502):  at android.os.AsyncTask.execute(AsyncTask.java:511)
09-06 18:35:36.055: E/WindowManager(2502):  at com.example.headache.ChartAct.onCreate(ChartAct.java:31)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.Activity.performCreate(Activity.java:4531)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1071)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2150)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2229)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.ActivityThread.access$600(ActivityThread.java:139)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1261)
09-06 18:35:36.055: E/WindowManager(2502):  at android.os.Handler.dispatchMessage(Handler.java:99)
09-06 18:35:36.055: E/WindowManager(2502):  at android.os.Looper.loop(Looper.java:154)
09-06 18:35:36.055: E/WindowManager(2502):  at android.app.ActivityThread.main(ActivityThread.java:4945)
09-06 18:35:36.055: E/WindowManager(2502):  at java.lang.reflect.Method.invokeNative(Native Method)
09-06 18:35:36.055: E/WindowManager(2502):  at java.lang.reflect.Method.invoke(Method.java:511)
09-06 18:35:36.055: E/WindowManager(2502):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-06 18:35:36.055: E/WindowManager(2502):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-06 18:35:36.055: E/WindowManager(2502):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

doInBackground()ビットマップを返すようにイメージを設定して、onPostExecute()

public class loadChart extends AsyncTask<Void, Void, Bitmap> {
    private ImageView img;
    private Context con;
    private ProgressDialog dialog;

    public loadChart(Context context, ImageView img1) {
        this.img = img1;
        this.con = context;
    }

    @Override
    protected void onPreExecute() {
        dialog = ProgressDialog.show(con, "Connecting:",
                "Loading. Please wait...", true);
        super.onPreExecute();
    }

    @Override
    protected Bitmap doInBackground(Void... params) {
        final Bitmap bitmap = DownloadImage();
        return bitmap;
    }

    @Override
    protected void onPostExecute(Bitmap result) {
        dialog.dismiss();
        img.setImageBitmap(result);
    }

Answer 2

からUIにアクセスすることはできません。doInBackground()これは、でビットマップを設定することによって行うことですimg.setImageBitmap(bitmap);。バックグラウンドアクティビティを使用しているときにこれを行う必要がある場合はrunOnUiThread()、UIアクセスコードをオブジェクトに移動するonPostExecute()か、ビットマップをオブジェクトに保存しますが、のUI要素に割り当てますonProgressUpdate()。一般に、AsyncTaskのドキュメントを参照してください。

Answer 3

から UI 要素を変更することはできませんdoInBackground()。

runOnUIThread()アクティビティのメソッドを使用するか、UI を変更するメソッドをメソッドに入れてみてくださいonPostExecute()。

詳細については、この回答をお読みください。