Android的：如何从服务器下载文件并将其保存在SD卡中的特定文件夹 [英] Android:How to download the File from the server and save it in specific folder in sdcard

问题描述

我在我的Andr​​oid应用程序一个要求。我需要下载和保存文件的SD卡中的特定文件夹编程。我已经开发的源$ C ​​$ C ..

和我的code是

 字符串DownloadUrl =htt​​p://myexample.com/android/;
     字符串文件名=myclock_db.db;

    DownloadDatabase（DownloadUrl，文件名）;

    //并且该方法是

公共无效DownloadDatabase（字符串DownloadUrl，字符串文件名）{
    尝试 {
        文件根= android.os.Environment.getExternalStorageDirectory（）;
        文件DIR =新的文件（root.getAbsolutePath（）+/ myclock /数据库）;
        如果（dir.exists（）== FALSE）{
             dir.mkdirs（）;
        }

        网址URL =新的URL（http://myexample.com/android/）;
        档案文件=新的文件（目录，文件名）;

        长的startTime = System.currentTimeMillis的（）;
        Log.d（下载管理器，下载网址：+网址）;
        Log.d（下载管理器，下载文件的名称：+文件名）;

        URLConnection的康涅狄格大学= url.openConnection（）;
        uconn.setReadTimeout（TIMEOUT_C​​ONNECTION）;
        uconn.setConnectTimeout（TIMEOUT_SOCKET）;

        InputStream的是= uconn.getInputStream（）;
        的BufferedInputStream bufferinstream =新的BufferedInputStream（是）;

        ByteArrayBuffer BAF =新ByteArrayBuffer（5000）;
        INT电流= 0;
        而（（电流= bufferinstream.read（））！=  -  1）{
            baf.append（（字节）电流）;
        }

        FileOutputStream中FOS =新的FileOutputStream（文件）;
        fos.write（baf.toByteArray（））;
        fos.flush（）;
        fos.close（）;
        Log.d（下载管理器，下载现成的+（（System.currentTimeMillis的（） -  startTime时）/ 1000）+SEC）;
        INT dotindex = fileName.lastIndexOf（'。'）;
        如果（dotindex＆GT; = 0）{
            文件名= fileName.substring（0，dotindex）;

    }
    赶上（IOException异常E）{
        Log.d（下载管理，错误：+ E）;
    }

}
 

现在的问题是与文件名myclock_db.db只有空文件在保存路径。但我需要下载和保存文件的内容，在特定的文件夹。试了几种方法来获取文件的下载，但我不能。谁能帮我解决了问题...

在此先感谢...

解决方案

您的下载网址是不是链接到的任何文件。这是一个目录。确保它的一个文件，并存在。另外，请检查您的logcat窗口错误日志。还有一个建议，它始终是更好地在catch块，而不是原木做的printStackTrace（）。其提供了错误的更详细的图。

更改此行：

 网​​址URL =新的URL（http://myexample.com/android/）;
 

到

 网​​址URL =新的URL（http://myexample.com/android/yourfilename.txt）; //某些文件网址
 

接下来，在catch块，加入这一行：

  e.printStackTrace（）;
 

另外，在目录路径，它应该是这样的：

 文件DIR =新的文件（root.getAbsolutePath（）+到/ mnt / SD卡/ myclock /数据库）;
 

而不是

 文件DIR =新的文件（root.getAbsolutePath（）+/ myclock /数据库）;
 

接下来，确保您已获得许可，以写入外部存储在Android清单。

I have one requirement in my Android application. I need to download and save file in specific folder of sdcard Programmatically. I have developed source code..

and my code is

String DownloadUrl = "http://myexample.com/android/";
     String fileName = "myclock_db.db";

    DownloadDatabase(DownloadUrl,fileName);

    // and the method is

public void DownloadDatabase(String DownloadUrl, String fileName) {
    try {
        File root = android.os.Environment.getExternalStorageDirectory();
        File dir = new File(root.getAbsolutePath() + "/myclock/databases");
        if(dir.exists() == false){
             dir.mkdirs();  
        }

        URL url = new URL("http://myexample.com/android/");
        File file = new File(dir,fileName);

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

        URLConnection uconn = url.openConnection();
        uconn.setReadTimeout(TIMEOUT_CONNECTION);
        uconn.setConnectTimeout(TIMEOUT_SOCKET);

        InputStream is = uconn.getInputStream();
        BufferedInputStream bufferinstream = new BufferedInputStream(is);

        ByteArrayBuffer baf = new ByteArrayBuffer(5000);
        int current = 0;
        while((current = bufferinstream.read()) != -1){
            baf.append((byte) current);
        }

        FileOutputStream fos = new FileOutputStream( file);
        fos.write(baf.toByteArray());
        fos.flush();
        fos.close();
        Log.d("DownloadManager" , "download ready in" + ((System.currentTimeMillis() - startTime)/1000) + "sec");
        int dotindex = fileName.lastIndexOf('.');
        if(dotindex>=0){
            fileName = fileName.substring(0,dotindex);

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

}

Now The issue is only empty file with filename myclock_db.db is saving in the path. but I need to download and save content of file in the specific folder. Tried several ways to get the file download, but I can't. Can anyone help me to solve the issue...

Thanks in advance...

解决方案

Your download URL is not a link to any file. It's a directory. Make sure its a file and exists. Also check your logcat window for error logs. One more suggestion, its always better to do a printStackTrace() in catch blocks instead of Logs. Its gives a more detailed view of the error.

Change this line:

    URL url = new URL("http://myexample.com/android/");

to:

    URL url = new URL("http://myexample.com/android/yourfilename.txt"); //some file url

Next, in catch block, add this line:

e.printStackTrace();

Also in the directory path, it should be something like this:

File dir = new File(root.getAbsolutePath() + "/mnt/sdcard/myclock/databases");

instead of

File dir = new File(root.getAbsolutePath() + "/myclock/databases");

Next, make sure you have acquired permission for writing to external storage in Android manifest.

这篇关于Android的：如何从服务器下载文件并将其保存在SD卡中的特定文件夹的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！