Question

我是android app开发者新手！

我有一个新问题。

我在我的MainActivity类中有这个void，一旦用户点击一个复选框就调用它，它的作用基本上就是将web上的文件下载到外部存储中名为test的文件夹中我在AndroidManifest.xml中添加了nessacry权限（有没有办法将文件下载到内部存储器），但它在运行时给出一个fc是日志的一部分......

LOG

D/DownloadManager(14956): download begining
D/DownloadManager(14956): download url:http://forum.xda-developers.com/attachment.php?attachmentid=2109443&d=1373572809l

D/DownloadManager(14956): downloaded file name:X-Reality_Engine.zipA
D/AndroidRuntime(14956): Shutting down VM
W/dalvikvm(14956): threadid=1: thread exiting with uncaught exception (group=0x4
1dc0ce0)
I/Process (14956): Sending signal. PID: 14956 SIG: 9
I/ActivityManager(23309): Process com.mythi.tests (pid 14956) has died.

MainActivity.java

   public void onCheckboxClicked5(View view) {

    String DownloadUrl = "http://forum.xda-developers.com/attachment.php?attachmentid=2109443&d=1373572809";
    String fileName = "X-Reality_Engine.zip";

        // Is the view now checked?
        boolean checked5 = ((CheckBox) view).isChecked();

        // Check which checkbox was clicked
        switch(view.getId()) {
            case R.id.checkBox5:
                PreferenceManager.getDefaultSharedPreferences(this).edit()
                .putBoolean("checkBox5", checked5).commit();
                if (checked5){
                    try {
                        File root = android.os.Environment.getExternalStorageDirectory();               

                        File dir = new File (root.getAbsolutePath() + "/test");
                        if(dir.exists()==false) {
                             dir.mkdirs();
                        }

                        URL url = new URL(DownloadUrl); //you can write here any link
                        File file = new File(dir, fileName);

                        long startTime = System.currentTimeMillis();
                        Log.d("DownloadManager", "download begining");
                        Log.d("DownloadManager", "download url:" + url);
                        Log.d("DownloadManager", "downloaded file name:" + fileName);

                        /* Open a connection to that URL. */
                        URLConnection ucon = url.openConnection();

                        /*
                         * Define InputStreams to read from the URLConnection.
                         */
                        InputStream is = ucon.getInputStream();
                        BufferedInputStream bis = new BufferedInputStream(is);

                        /*
                         * Read bytes to the Buffer until there is nothing more to read(-1).
                         */
                        ByteArrayBuffer baf = new ByteArrayBuffer(5000);
                        int current = 0;
                        while ((current = bis.read()) != -1) {
                           baf.append((byte) current);
                        }


                        /* Convert the Bytes read to a String. */
                        FileOutputStream fos = new FileOutputStream(file);
                        fos.write(baf.toByteArray());
                        fos.flush();
                        fos.close();
                        Log.d("DownloadManager", "download ready in" + ((System.currentTimeMillis() - startTime) / 1000) + " sec");

                } catch (IOException e) {
                    Log.d("DownloadManager", "Error: " + e);
                }

             }

Answer 1

在您的日志中没有说，但我发现您没有使用单独的线程进行网络访问。这是无效的情况，您的应用程序将崩溃。您必须创建一个单独的线程才能从Web下载该文件。 SEE THIS Android docs

Answer 2

将此代码添加到onCLick按钮，或者您点击下载的任何按钮或行

public void downloadFile(){
    String DownloadUrl = "Paste Url to download a pdf file here…";
    DownloadManager.Request request = new DownloadManager.Request(Uri.parse(DownloadUrl));
    request.setDescription("sample pdf file for testing");   //appears the same in Notification bar while downloading

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        request.allowScanningByMediaScanner();
        request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
    }
    request.setDestinationInExternalFilesDir(getApplicationContext(),null, "whatevernameoffileuwant.extensionoffilw");
//request.setDestinationInExternalFilesDir(getApplicationContext(),null,  "Sample.pdf");
    // get download service and enqueue file
    DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
    manager.enqueue(request);
}

Android文件下载到SD卡无法正常工作

2 个答案: