Question

你可以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)

我这样做

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");
    }

我称之为双向，但同样的错误原因是什么？

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

Answer 1

如果您使用的是HONEYCOMB或更高版本，则需要使用AsyncTask来调用与网络相关的操作。

See this answer

Answer 2

使用下载管理器。 下载管理器的优势：

如果连接丢失，则自动重试下载。
它照顾工人线程，即背景线程。

它会在导航栏中显示已下载状态及进度状态

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); 
}
 }

请勿忘记在manifest.xml

如何从服务器下载文件获取错误文件？

2 个答案: