如何从服务器下载文件找不到错误文件？

Question

你能告诉我如何从服务器下载文件吗？我收到错误填充未找到错误？

07-30 17:10:28.849: W/System.err(14900): java.io.FileNotFoundException: /testnaveen: open failed: EROFS (Read-only file system)
07-30 17:10:28.849: W/System.err(14900):    at libcore.io.IoBridge.open(IoBridge.java:409)
07-30 17:10:28.849: W/System.err(14900):    at java.io.FileOutputStream.<init>(FileOutputStream.java:88)
07-30 17:10:28.849: W/System.err(14900):    at java.io.FileOutputStream.<init>(FileOutputStream.java:128)
07-30 17:10:28.849: W/System.err(14900):    at java.io.FileOutputStream.<init>(FileOutputStream.java:117)
07-30 17:10:28.849: W/System.err(14900):    at com.mobilecem.atms.GlobalFunction.downloadFileFromServer(GlobalFunction.java:147)

我就是这样的

public static void downloadFileFromServer(String filename, String urlString) throws MalformedURLException, IOException
    {
        BufferedInputStream in = null;
        FileOutputStream fout = null;
        try
        {
            URL url = new URL(urlString);

            in = new BufferedInputStream(url.openStream());
            fout = new FileOutputStream(filename);

            byte data[] = new byte[1024];
            int count;
            while ((count = in.read(data, 0, 1024)) != -1)
            {
                fout.write(data, 0, count);
                System.out.println(count);
            }
        }
        finally
        {
            if (in != null)
                    in.close();
            if (fout != null)
                    fout.close();
        }
        System.out.println("Done");
    }

我两种方式都调用，但是为什么会出现同样的错误？

GlobalFunction.downloadFileFromServer("test", "http://www.example.com/inputParameters.js");
GlobalFunction.downloadFileFromServer( new File(Activity.this.getFilesDir(),"www").getAbsolutePath(), "url");

Answer 1

使用下载管理器。 下载管理器的优势：

1. 如果连接丢失，它会自动重试下载。
2. 它负责工作线程，即后台线程。

3. 它在导航托盘中显示您的下载状态和进度状态

   package com.example.testing;
   import android.app.Activity;
   import android.app.DownloadManager;
   import android.content.Context;
   import android.net.Uri;
   import android.os.Bundle;
   import android.os.Environment;
   import android.util.Log;
   
   public class FileDownloading extends Activity
   {
   
   @Override
   protected void onCreate(Bundle savedInstanceState)
   {
       // TODO Auto-generated method stub
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       startDownload("http://www.example.com/inputParameters.js","inputParameters.js");
   }
   public void startDownload(String url ,String fileName)
   {
       Log.d("Download Url", url);
       DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
       request.setTitle("Your File Name");
       request.setDescription(fileName+" is downloading..");
       request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, fileName);
       DownloadManager downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE); 
       long downloadID = downloadManager.enqueue(request); 
   }
    }
   

别忘了在manifest.xml中使用互联网和存储权限

Answer 2

如果您使用 HONEYCOMB 或更高版本，则需要使用AsyncTask 调用网络相关操作。

See this answer