Question

我试图下载apk文件然后安装它我已经使用外部存储目录完成了它，但是当我在本地目录中下载文件时，我无法解析它。

以下是OnCreate方法的代码

final DownloadTask downloadTask = new DownloadTask(this);       
downloadTask.execute("http://file.appsapk.com/wp-content/uploads/apps-2/Gmail.apk","Gmail.apk");

DownloadTask是一个从AsyncTask扩展而来的类。这是后台任务：

@Override
    protected String doInBackground(String... sUrl) {
        file_name=sUrl[1];
        Boolean isSDPresent = android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);
        if (isSDPresent) {
            directory = new File(Environment.getExternalStorageDirectory()+File.separator+"app_directory");
        }
        else
        {
            directory = getFilesDir();

        }
        if (!directory.exists()) 
            directory.mkdirs();
        InputStream input = null;
        OutputStream output = null;
        HttpURLConnection connection = null;
        try {
            URL url = new URL(sUrl[0]);
            connection = (HttpURLConnection) url.openConnection();
            connection.connect();
            if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
                return "Server returned HTTP " + connection.getResponseCode()
                        + " " + connection.getResponseMessage();
            }

            int fileLength = connection.getContentLength();
            input = connection.getInputStream();
            output = new FileOutputStream(directory+"/"+file_name);
            byte[] buffer = new byte[1024];
            long total = 0;
            int count;
            while ((count = input.read(buffer)) != -1) {
                if (isCancelled()) {
                    input.close();
                    return null;
                }
                total += count;
                if (fileLength > 0) // only if total length is known
                    publishProgress((int) (total * 100 / fileLength));
                output.write(buffer, 0, count);
            }
        } catch (Exception e) {
            return e.toString();
        } finally {
            try {
                if (input != null)
                    input.close();

                if (output != null)
                    output.close();
            } catch (IOException ignored) {
            }

            if (connection != null)
                connection.disconnect();
        }
        return null;
    }

这是在第一个完成下载文件后运行的后执行方法：

   @Override
    protected void onPostExecute(String result) {
        mWakeLock.release();
        mProgressDialog.dismiss();
        if (result != null)
        {
            Toast.makeText(context,"Download error: "+result, Toast.LENGTH_LONG).show();
        }
        else
        {
            Toast.makeText(context, "File downloaded", Toast.LENGTH_SHORT).show();
            File file = new File(directory, file_name);
            Intent promptInstall = new Intent(Intent.ACTION_VIEW)
                .setDataAndType(Uri.fromFile(file),
                        "application/vnd.android.package-archive");
           context.startActivity(promptInstall);
           finish();

        }

它与外部存储完美匹配，但它不会与外部存储一起运行。为什么不呢？

Answer 1

尝试使用openfileoutput（）而不是OutputStream将文件保存在内部存储中并允许其可读。 http://developer.android.com/guide/topics/data/data-storage.html#filesInternal。包错误主要是由内部存储的许可引起的。

Answer 2

因为android应用程序无法从另一个应用程序文件读取，如果它是使用PRIVATE模式编写的。所以你必须改变文件的模式。我刚刚修改了下面的onPostExecute（）方法的其他部分。

    try {
        String tempfile="xyzfile";
        File file = new File(directory, file_name);
        FileInputStream inStream = new FileInputStream(file);
        FileOutputStream fos = context.openFileOutput(tempfile,
                context.MODE_WORLD_WRITEABLE | context.MODE_WORLD_READABLE);

        byte[] buffer = new byte[1024];
        int length;
        // copy the file content in bytes
        while ((length = inStream.read(buffer)) > 0) {

            fos.write(buffer, 0, length);

        }
        inStream.close();
        fos.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
    File file = new File(context.getFilesDir(), tempfile);
    Intent promptInstall = new Intent(Intent.ACTION_VIEW).setDataAndType(
            Uri.fromFile(file), "application/vnd.android.package-archive");
    context.startActivity(promptInstall);

如何从内部存储文件安装应用程序

2 个答案: