java - 尝试关闭 HttpURLConnection

Question

我向我的用户提供下载文件的机会。

有时这个文件非常大，我在下载时实现一个 ProgressDialog。

好吧，如果用户点击返回，我想取消AsyncTask并关闭连接:

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pd = new ProgressDialog(main);
                pd.setMessage("Downloading PDF...");
                pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                pd.setCancelable(true);
                pd.setCanceledOnTouchOutside(false);
                pd.setOnCancelListener(new OnCancelListener() {
                    public void onCancel(DialogInterface var1) {
                        cancel(true);

                        if(httppost != null) {
                            httppost.abort();
                        }
                        try {
                            if (downloader != null) {
                                downloader.closeConnection();
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                        }

                    }
                });
                pd.setIndeterminate(false);
                pd.show();
            } 

我的downloader是一个自己的类，其中closeConnection的函数是:

public void closeConnection() { // urlConnection is a HttpURLConnection.
    if (urlConnection!=null)
        try {
            urlConnection.getInputStream().close();
        } catch (Exception e) {
            e.printStackTrace();
        }
}

但是当我这样做时，我得到:

06-25 21:13:03.169: W/InputEventReceiver(18144): Attempted to finish an input event but the input event receiver has already been disposed.
06-25 21:13:03.179: W/System.err(18144): android.os.NetworkOnMainThreadException
06-25 21:13:03.179: W/System.err(18144):    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1156)
06-25 21:13:03.179: W/System.err(18144):    at libcore.io.BlockGuardOs.recvfrom(BlockGuardOs.java:163)
06-25 21:13:03.179: W/System.err(18144):    at libcore.io.IoBridge.recvfrom(IoBridge.java:506)
06-25 21:13:03.179: W/System.err(18144):    at java.net.PlainSocketImpl.read(PlainSocketImpl.java:489)
06-25 21:13:03.179: W/System.err(18144):    at java.net.PlainSocketImpl.access$000(PlainSocketImpl.java:46)
06-25 21:13:03.179: W/System.err(18144):    at java.net.PlainSocketImpl$PlainSocketInputStream.read(PlainSocketImpl.java:241)
06-25 21:13:03.179: W/System.err(18144):    at java.io.BufferedInputStream.read(BufferedInputStream.java:283)
06-25 21:13:03.179: W/System.err(18144):    at com.android.okhttp.internal.http.HttpTransport$FixedLengthInputStream.read(HttpTransport.java:386)
06-25 21:13:03.179: W/System.err(18144):    at libcore.io.Streams.skipByReading(Streams.java:158)
06-25 21:13:03.179: W/System.err(18144):    at java.io.InputStream.skip(InputStream.java:227)
06-25 21:13:03.179: W/System.err(18144):    at com.android.okhttp.internal.Util.skipAll(Util.java:249)
06-25 21:13:03.189: W/System.err(18144):    at com.android.okhttp.internal.http.HttpTransport.discardStream(HttpTransport.java:190)
06-25 21:13:03.189: W/System.err(18144):    at com.android.okhttp.internal.http.HttpTransport.access$200(HttpTransport.java:32)
06-25 21:13:03.189: W/System.err(18144):    at com.android.okhttp.internal.http.HttpTransport$FixedLengthInputStream.close(HttpTransport.java:408)
06-25 21:13:03.189: W/System.err(18144):    at farma.r.resources.Downloader.closeConnection(Downloader.java:23)
06-25 21:13:03.189: W/System.err(18144):    at farma.r.free.fragments.promo.mainPromoFragment$ChiamataPOSTPDF$1.onCancel(mainPromoFragment.java:292)
06-25 21:13:03.189: W/System.err(18144):    at android.app.Dialog$ListenersHandler.handleMessage(Dialog.java:1253)
06-25 21:13:03.189: W/System.err(18144):    at android.os.Handler.dispatchMessage(Handler.java:102)
06-25 21:13:03.189: W/System.err(18144):    at android.os.Looper.loop(Looper.java:157)
06-25 21:13:03.189: W/System.err(18144):    at android.app.ActivityThread.main(ActivityThread.java:5356)
06-25 21:13:03.189: W/System.err(18144):    at java.lang.reflect.Method.invokeNative(Native Method)
06-25 21:13:03.189: W/System.err(18144):    at java.lang.reflect.Method.invoke(Method.java:515)
06-25 21:13:03.189: W/System.err(18144):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
06-25 21:13:03.189: W/System.err(18144):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
06-25 21:13:03.189: W/System.err(18144):    at dalvik.system.NativeStart.main(Native Method)

我在 AsyncTask 上执行此操作，在 doInBackGround() 中下载

我做错了什么？

如果我不关闭连接，我的用户将一直下载内容直到最后，从而消耗更多数据。

Answer 1

您有一个NetworkOnMainThreadExeption。显然，onCancel() 中的代码在主 ui 线程上运行。您可以更好地检查 doInBackground 中的 ps.isCancelled() 并取消/中止并在那里关闭。或者启动一个线程。