如何下载文件，在后台服务？ [英] how to download file with service in the background?

问题描述

我在做一个机器人库的应用程序，可以下载并显示特殊文件。现在我需要编写下载文件在后台的服务！是否有样品服务？

和我要保存在SD文件，因为用户可以更新应用程序，不应该错过下载的文件。

如果您有建议或意见对于这一点，写信给我，请。

解决方案

 尝试{
    网址URL =新的URL（URL从apk文件被下载）;
    HttpURLConnection的的URLConnection =（HttpURLConnection类）url.openConnection（）;
    urlConnection.setRequestMethod（GET）;
    urlConnection.setDoOutput（真正的）;
    urlConnection.connect（）;

    文件SD卡= Environment.getExternalStorageDirectory（）;
    档案文件=新的文件（SD卡，FILENAME.EXT）;

    FileOutputStream中fileOutput =新的FileOutputStream（文件）;
    InputStream中的InputStream = urlConnection.getInputStream（）;

    byte []的缓冲区=新的字节[1024];
    INT BufferLength中= 0;

    而（量（bufferLength = inputStream.read（缓冲液））大于0）{
        fileOutput.write（缓冲液，0，BufferLength中）;
    }
    fileOutput.close（）;

}赶上（MalformedURLException异常E）{
        e.printStackTrace（）;
}赶上（IOException异常E）{
        e.printStackTrace（）;
}
}
 

权限：：要写入外部存储，则需要添加该权限：

 ＆LT;使用-权限的Andr​​oid：名称=android.permission.WRITE_EXTERNAL_STORAG​​E/＆GT;
 

注意：：您可以使用上面code获得下载并保存在SD卡上的文件。您可以使用 AsysnTask 或线程运行此code在后台。

I'm making a android library app that can download and show special files. now I need to write a service that download file in background! are there samples for services?

and I want to save files in SD, because users can update app and don't should miss downloaded files.

If you have a suggest or opinion for this, write me, please.

解决方案

try {
    URL url = new URL("url from apk file is to be downloaded");
    HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
    urlConnection.setRequestMethod("GET");
    urlConnection.setDoOutput(true);
    urlConnection.connect();

    File sdcard = Environment.getExternalStorageDirectory();
    File file = new File(sdcard, "filename.ext");

    FileOutputStream fileOutput = new FileOutputStream(file);
    InputStream inputStream = urlConnection.getInputStream();

    byte[] buffer = new byte[1024];
    int bufferLength = 0;

    while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
        fileOutput.write(buffer, 0, bufferLength);
    }
    fileOutput.close();

} catch (MalformedURLException e) {
        e.printStackTrace();
} catch (IOException e) {
        e.printStackTrace();
}
}

Permission: To write to external storage, you need to add this permission:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Note: you can use above code to get the file downloaded and saved in the SD card. You can run this code in background using AsysnTask or thread.

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